Phosphorus as a limiting factor on sustainable greywater irrigation

Science of the Total Environment 456–457 (2013) 287–298

Contents lists available at SciVerse ScienceDirect

Science of the Total Environment journal homepage: www.elsevier.com/locate/scitotenv

Phosphorus as a limiting factor on sustainable greywater irrigation Ryan D.R. Turner a,⁎, Geoffrey D. Will b, Les A. Dawes b, Edward A. Gardner c, David J. Lyons a a Water Quality and Investigations, Environmental Monitoring and Assessment Science, Science Delivery, The State of Queensland, Department of Science, Information Technology, Innovation and the Arts, Dutton Park Queensland 4102, Australia b School of Physical and Chemical Sciences, Queensland University of Technology, Brisbane Queensland, Australia c Institute for Resource Industries and Sustainability, Central Queensland University, Rockhampton, Australia

H I G H L I G H T S • • • • •

We assessed four residential lots that had been irrigated with greywater for four years. Each lot was monitored for irrigation volumes applied and various chemical and physical water quality parameters. A Mechlich3 Phosphorus ratio and Phosphate Environmental Risk Index was used to determine environmental risk of phosphorus. Reported soil phosphorus results were also compared to theoretical greywater irrigation loadings. Sustainable greywater reuse is possible however incorrect use can result in phosphorus impacting the environment.

a r t i c l e

i n f o

Article history: Received 7 November 2012 Received in revised form 5 February 2013 Accepted 19 February 2013 Available online 23 April 2013 Keywords: Greywater Irrigation Phosphorus Soil Sustainability Water reuse

a b s t r a c t Water reuse through greywater irrigation has been adopted worldwide and has been proposed as a potential sustainable solution to increased water demands. Despite widespread adoption, there is limited domestic knowledge of greywater reuse. There is no pressure to produce low-level phosphorus products and current guidelines and legislation, such as those in Australia, may be inadequate due to the lack of long-term data to provide a sound scientific basis. Research has clearly identified phosphorus as a potential environmental risk to waterways from many forms of irrigation. To assess the sustainability of greywater irrigation, this study compared four residential lots that had been irrigated with greywater for four years and adjacent non-irrigated lots that acted as controls. Each lot was monitored for the volume of greywater applied and selected physic-chemical water quality parameters and soil chemistry profiles were analysed. The non-irrigated soil profiles showed low levels of phosphorus and were used as controls. The Mechlich3 Phosphorus ratio (M3PSR) and Phosphate Environmental Risk Index (PERI) were used to determine the environmental risk of phosphorus leaching from the irrigated soils. Soil phosphorus concentrations were compared to theoretical greywater irrigation loadings. The measured phosphorus soil concentrations and the estimated greywater loadings were of similar magnitude. Sustainable greywater reuse is possible; however incorrect use and/or lack of understanding of how household products affect greywater can result in phosphorus posing a significant risk to the environment. © 2013 Elsevier B.V. All rights reserved.

1. Introduction Water scarcity is increasingly becoming a problem worldwide (Godfrey et al., 2009; Jury and Vaux, 2007). Greywater irrigation has been adopted as one way to combat this scarcity (Maimon et al., 2010; Eriksson and Donner, 2009; Winward et al., 2008) and to help ensure the sustainability of this resource (Al-Jayyousi, 2003). It has been clearly demonstrated that greywater re-use is a potential solution to increased water demands (Gross et al., 2007; Jury and Vaux, 2007), however the sustainability of this practice has been questioned (Wiel-Shafran et al., 2006) as environmental pollution is probable if greywater is used incorrectly. ⁎ Corresponding author. Tel.: +61 731705608; fax: +61 731705799. E-mail address: [email protected] (R.D.R. Turner). 0048-9697/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.scitotenv.2013.02.061

The commercial drive to produce low phosphorus cleaning products is low due to consumer habits and lack of legislation (Knud-Hansen, 1993). Consequently, high levels of phosphorus can be irrigated onto soil via greywater recycling (Patterson, 2004). To help change consumer habits Stevens et al. (2011b) promote a “GreySmart” web based tool, displaying information in a simplified manner by presenting consolidated research, allowing individuals to assess and potentially practice safe and sustainable greywater reuse (Greysmart, 2012). However even with web-based tools, consumer knowledge of the impacts and sustainability of greywater irrigation is inadequate (Whitehead and Patterson, 2007). Furthermore, guidelines and legislation on greywater irrigation tend to focus on human health (Maimon et al., 2010; Avvannavar and Mani, 2007) rather than environmental and sustainability issues. Additionally, both the Queensland (Department of State Development, Infrastructure and Planning, 2007) and Australian guidelines; (Environment Protection

288

R.D.R. Turner et al. / Science of the Total Environment 456–457 (2013) 287–298

and Heritage Council, 2006) are incomplete due to limited scientific data and do not require the measurement of phosphorus loadings. Research has clearly identified phosphorus as a potential risk for many forms of irrigation (Christova-Boal et al., 1996) and can accelerate freshwater eutrophication (Koopmans, 2002; Sharpley, 1995; Sharpley et al., 1995). A major source of phosphorus in greywater is sodium tripolyphosphate or potassium phosphates (ReVelle and ReVelle, 1988; Jenkins et al., 1973) used as builders in detergents (Lanfax Laboratories, 2009; Hammond, 1971). The primary role of builders is to reduce the hardness of the water and hence improve washing performance. This is achieved by binding to and neutralising calcium, magnesium, iron as well as manganese ions thus enabling the surfactant to work on the dirt and improving washing performance (Jenkins et al., 1973). Greywater reuse typically occurs via irrigation (Travis et al., 2010; Wiel- Howard et al., 2007; Wiel-Shafran et al., 2006) although using it to flush toilets is becoming more common (Godfrey et al., 2009; March and Gual, 2009; Jeppesen, 1996). Other uses for greywater include; washing machines and washing paths, walls, and vehicles (Department of State Development, Infrastructure and Planning, 2007). These latter types of reuse need guidelines on the final quality of greywater since the runoff will go straight into the stormwater system and then local waterways without treatment. The economics of greywater treatment and reuse encourages the use of simple forms of irrigation and minimal treatment. Examples of simple forms of irrigation include bucketing laundry water, diverting washing machine waste water and (95 L per household per day) diverting shower water (140 L per household per day) (Beal et al., 2011). Due to minimal public education about the correct use of greywater, suburban subdivisions where greywater irrigation is practiced potentially face future environmental contamination issues. When phosphate is irrigated onto soil, it can be taken up by plants (Barton et al., 2005) but the majority is absorbed to iron and/or aluminum oxy-hydroxides (de Mesquita Filho and Torrent, 1993; Lewis et al., 1981), and aluminosilicates (Barton et al., 2005) in soils via ligand exchange. The degree of phosphorus sorption to soil is directly related to the concentration of these minerals. Once all the active phosphorus sorption sites have effectively been saturated and equilibrium reached, further irrigation results in a net increase in free phosphorus. The free phosphorus can move down the soil profile and potentially meet groundwater or move across the soil surface by interacting with surface water runoff. Two processes generally explain the chemical availability of free phosphorus; desorption of phosphorus from sorption sites on iron and aluminium oxyhydroxides, associated with clay mineral surfaces and organic matter; and dissolution of phosphorus compounds present as soil minerals and or fertiliser (Moody, 2011). This movement of phosphorus can cause environmental contamination, and contribute to freshwater ecosystem eutrophication (Gross et al., 2005; Sharpley et al., 1996) thus potentially compromising the sustainability of greywater irrigation. Two alternate approaches have been proposed to assess the sustainability of effluent irrigation, which contain phosphorus, on soils. Sims et al. (2002) suggested using a molar ratio of Mehlich3 extractable phosphorus to Mehlich3 extractable iron and Mehlich3 extractable aluminium (M3PSRICPAES) as an indicator of the potential loss of phosphorus from soils to surface and groundwater. Subsequently Maguire and Sims (2002) classified the potential for environmental harm posed by phosphorus in terms of Mehlich3 saturation ratios. Ratios of less than 0.10 indicate soil phosphorus saturations below environmental concern; ratios between 0.10 and 0.15 indicate soil phosphorus saturations where they may be an environmental concern; and a ratio greater than 0.2 indicates soil phosphorus saturations that are of environmental concern (Maguire and Sims, 2002). The second approach, developed by Moody (2011), builds on earlier work that found P loss in irrigated soils was heavily governed by the water quality of the irrigated greywater (Roesner et al., 2006) and the chemistry and physical properties of soil (Travis et al., 2010;

Wiel-Shafran et al., 2006). This method determines the ratio of Colwell P to the phosphorus buffering index and calls this the Phosphate Environmental Risk Index (PERI). A PERI value greater than 2.0 demonstrates a potential environmental hazard due to the loss of phosphorus from the soil. In determining the sustainability of greywater irrigation two aspects should be considered. Firstly is there a net benefit from greywater irrigation in terms of water reuse? This has been demonstrated by many researchers and is not questioned by this study (Pinto and Maheshwari, 2010; Regelsberger et al., 2007; Whitehead and Patterson, 2007; Khalil et al., 2004; Al-Jayyousi, 2003). Secondly can potential impacts from greywater irrigation on soil, waterways and groundwater be managed sufficiently that there are no adverse effects? This research assesses the sustainability of greywater irrigation and its potential impacts. To ensure greywater irrigation does not adversely impact the surrounding environment sustainable phosphorus irrigation loadings should be introduced into legislation. Furthermore, irrigation assessment models such as MEDLI (Gardner et al., 2002) should be utilised and enhanced (for sub-surface irrigation) to assess the suitability of the site to receive greywater. Guidelines for greywater application should be updated to address phosphorus impacts along with education programs to encourage residents to maintain the environmental sustainability of their land (Patterson, 2004). This paper assesses environmental impacts as a result of four years of greywater irrigation at four residential lots and evaluates the long term sustainability of these sites from phosphorus loading. 2. Methods 2.1. Research design The design of this study included: 1) Collection of greywater and soil samples from four residential urban lots. 2) Collection of soil samples as controls from adjacent non-irrigated lots. 3) Surveys to determine households’ use of products in the laundry and kitchen as well as the frequency of washing and bathing. 4) Chemical analysis of greywater. 5) Chemical and physical analysis of soil profiles. 6) Soil profiles were evaluated to ascertain phosphorus sustainability. 7) Actual phosphorus loadings in the soil were compared with estimated phosphorus loadings based on greywater chemistry and the results were used to estimate future sustainable phosphorus soil loadings. 2.2. Study area The study area was a 22 lot residential subdivision with a total area of 3.8 ha, located approximately 10 km west of Brisbane, Queensland, Australia (Fig. 1). Individual lots ranged in area between 800 and 1800 m2. The majority of the study area is steep with slopes up to 20% with each lot being terraced. Overland flow from the subdivision flows into Enoggera Creek — a high ecological value waterway (Sinclair Knight Merz, 2011; Brisbane City Council, 2010). Each lot has a 200 m 2 grassed transpiration area for greywater irrigation. The water supply for each household is captured rain water supplemented by mains potable water. Four lots were chosen for this study. These were selected based on the results of workplace health and safety and site access considerations, and household demographics. The household of each selected lot was surveyed to determine what cleaning products were utilised in the laundry and kitchen. In addition, an adult from each household was interviewed on their knowledge and understanding of the importance and sustainability of greywater reuse as well as water efficiency. This gave insights into the residents’ consumer attitudes and beliefs in and knowledge of greywater reuse.

R.D.R. Turner et al. / Science of the Total Environment 456–457 (2013) 287–298

289

Fig. 1. Location of study area and the four sites (*with dashed borders) selected for detailed investigation. Direction of slope is shown by dashed arrows.

2.3. Greywater

2.4. Soil

The greywater from the four selected lots was treated and stored in separate vermi-culture (Biolytix, 2005) greywater treatment systems. Greywater consisted of all water discharged from the bathrooms, laundry and kitchen apart from blackwater (toilet waste). The greywater from each household was subsurface drip irrigated onto a transpiration area, termed “transpiration zone”. A moisture sensor is located in each transpiration zone to reduce over irrigation. If the sensor reported the soil was saturated, greywater was automatically diverted to sewer. Water discharges from each household were measured between May 2005 and July 2009 using water meters and electronic counters, allowing the calculation of greywater volumes sent to either sewer or irrigation. Grab samples of greywater were taken over five periods: February 2006, May 2006, June 2006 November 2007 and April 2009. Average characteristics of the greywater samples taken during 2006 were presented by Beal et al. (2008). Each greywater sample was a composite 24-hour sample taken directly from the irrigation outlet by a capillary tube with a bleed valve. These were collected in a 2 L bottle stored on ice and retrieved daily. Each sample was subsampled according to the Australian Standard: AS/NZS 5667.1:1998 1998 (Standards Australia, 1998a, 1998b) and sent to NATA accredited laboratories for chemical analysis (Kaus, 2010). Greywater samples were analysed for the following parameters: total Kjeldahl nitrogen as N (TKN) and total Kjeldahl phosphorus as P (TP) by Flow Injection Analysis (Eaton et al., 2005); calcium (Ca), potassium (K), magnesium (Mg) and sodium (Na) using Inductively Coupled Plasma-Optical Emission Spectrometer simultaneous detection analysis (Eaton et al., 2005; Varian, 2001); pH at 25 °C and electrical conductivity (EC) at 25 °C by electrode (Eaton et al., 2005) and Sodium Adsorption Ratio (SAR) (Rayment and Lyons, 2011). The SAR was calculated using the following formula:

Up to five individual soil cores were taken from the transpiration zones of each irrigated lot, using methods based on Rayment and Lyons (2011) and Peverill et al. (1999) and these soils were termed “irrigated soils”. Each core was hand augured to a depth of 1.5 m or until auger refusal. The soil depth profiles were only reported to 0.5 m depth to permit consistent comparisons of all cores. Each soil core was sampled in 100 mm depth segments to establish detailed depth profiles, for each transpiration zone. A total of 12 soil cores were collected from the adjacent non-irrigated lots. These acted as controls, as the study area had been established for four years prior to the sampling. Sampling occurred between 22nd of January to 5 February 2009. Soil chemistry profiles were analysed every 100 mm. The average value for each parameter (based on the five irrigated cores) at each 100 mm depth was calculated. The same was done for the 12 non-irrigated cores. Each soil sample was analysed for: air dry moisture content at 105 °C (Rayment and Lyons, 2011); pH and electrical conductivity (EC) by 1:5 soil water extraction (Rayment and Lyons, 2011; Eaton et al., 2005) extractable phosphorus as P by Colwell 0.5 M NaHCO3 auto analyser (Rayment and Lyons, 2011); aluminium (Al), iron (Fe) and phosphorus (P) by elemental analysis of Mehlich3 extracts using Inductively Coupled Plasma-Optical Emission Spectrometer simultaneous detection analysis (ICP-OES) (Rayment and Lyons, 2011); phosphorus single point buffer index (PBI) by ICP-OES (Rayment and Lyons, 2011); and particle size analysis for coarse sand (2.0 to 0.2 mm), fine sand (0.2 to 0.02 mm) silt (0.02 to 0.002 mm) and clay (less than 0.002 mm) (Standards Australia, 2003; Thorburn and Shaw, 1987). The results for Colwell P were further assessed with a non-parametric Kruskal–Wallis test.




þ

Na 22:989768



SAR ¼ rffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi h
2þ 
2þ iffi Mg Ca 0:5 20:039 þ 12:1525 where Na+, Ca2+ and Mg2+ are concentrations expressed as mg L−1.

2.5. Phosphorus irrigation sustainability The sustainability of greywater irrigation can be assessed by comparing the phosphorus concentrations in greywater and the ability of the soil to bind phosphorus. Modeling programs such as MEDLI (Gardner et al., 2002) have been designed to assess the suitability of irrigation areas. However the soil analysis for P dynamics required for the model is expensive and not routinely conducted in Australian

290

R.D.R. Turner et al. / Science of the Total Environment 456–457 (2013) 287–298

laboratories. Two alternate approaches have been suggested (1) the Mehlich3 P saturation ratio (Eq. (1)) (Sims et al., 2002) and (2) the PERI method (Moody, 2011) (Eq. (2)). Eq. (1) Mehlich3 P saturation ratio 

P M3 þ FeM3 AlM3

M3PSR ¼



Eq. (5) Site soil bulk density ρ ¼ ððS=100Þ1:5Þ þ ððI=100Þ1:3Þ þ ððC=100Þ1:2Þ where:

ρ

where: S M3PSR Mehlich3 PM3 Mehlich3 AlM3 Mehlich3 FeM3 Mehlich3 Eq. (2) PERI β¼

P saturation ratio; extracted P expressed in mmol kg −1; extracted Al expressed in mmol kg −1; and extracted Fe expressed in mmol kg −1.

PBI Cp

I C

soil bulk density (BD) in grams per cubic centimetre (g cm−3) (determined by calculating every 100 mm horizon and obtaining an average “site soil bulk density”); particle size analysis percent sand (Sand bulk density = 1.5 g cm −3); particle size analysis percent silt (Silt bulk density = 1.3 g cm−3); and particle size analysis percent clay (Clay bulk density = 1.2 g cm −3).

3. Results and discussion

where:

3.1. Study area

β ¼ PERI PBI Cp

Phosphorus single point buffer index by ICP-OES; and Colwell extractable phosphorus as P by auto analyser mg L −1.

2.6. Phosphorus loading comparison The total soil P load was calculated using Eqs. (3) to (5) (Johnson, 2012) and compared to the estimated greywater irrigation loads. Eq. (3) Soil P load ∅° ¼°ΔNF where: soil P (Colwell P in mg kg −1) nutrient content in kg ha −1; soil mass in kg ha −1; P nutrient content in mg kg −1; and conversion factor to convert concentration.

∅ Δ N F

Eq. (4) Soil mass Δ ¼ Tρð1−SÞ10

5

where: soil mass in kg ha −1; T = thickness of soil horizon in cm; site soil bulk density in g cm −3; and soil fraction greater than 2 mm in decimal percent.

Δ ρ S

Properties of the soil in the transpiration zones can be understood by considering household dynamics and the volume and time of irrigations. These characteristics are shown in Table 1 and are a summary of data collected during May 2005 to July 2009. Lots A, C and D had similar total volumes of greywater applied to their transpiration zones, whereas lot B received markedly less irrigation (due to the smaller number of occupants) (Table 1). The large family in lot C resulted in the greatest volume of greywater being irrigated, despite nearly fifty percent being sent to sewer. Lot C also had the highest daily irrigation volume, lots A and D had similar moderate daily volumes applied, while lot B received considerably less irrigation. Interestingly, despite the different length of irrigation and different volumes of greywater produced, the greywater volume irrigated per person per day are very similar — all being within the narrow range of 65 to 71 L person−1 day−1 (Table 1). These values are markedly lower than previous estimates of greywater generation. The Department of State Development, Infrastructure and Planning (2007), estimates greywater generation in sewered areas at 95 L person−1 day−1 and at 120 L person−1 day−1 for un-sewered areas. Queensland Urban Utilities (2012), estimated 106 L person−1 day−1 for sewered areas whereas Beal et al. (2011) estimated for all south east Queensland volumes ranging from 85 to 119 L person−1 day−1. In another approach, Diaper et al. (2008) published an average value of 230 l per household per day. This is consistent with the range of 134 to 388 l per household per day obtained in this study. Such measures of greywater generation are not informative, as the volumes generated are directly related to the number of occupants in each household. Surveyed results of each households average weekly habits’ are presented in Table 2. The larger number of occupants residing in lot

Table 1 Greywater (GW) irrigation figures. Lot

Days of potential irrigation

Number of occupants

Total GW produced (L)

GW Irrigated (L)

% GW irrigated

Total GW irrigated (L day−1)

GW irrigated (L person−1 day−1)

A B C D

1678 1284 1255 1561

4 2 6 4

485 172 940 445

478 172 486 433

98.5 99.8 51.8 97.2

285 134 388 277

71 67 64 69

784 486 820 858

612 087 887 188

R.D.R. Turner et al. / Science of the Total Environment 456–457 (2013) 287–298

291

Table 2 Summary of average weekly house activities that can impact greywater quantity and composition. Activity Lot A (4 occupants)a Clothes washing (number of loads) Dishwasher Washing up dishes (manually) Shower (number of showers) Lot B (2 occupants) Clothes washing (number of loads) Dishwasher Washing up dishes (manually) Shower (number of showers) Lot C (6 occupants) Clothes washing (number of loads) Dishwasher Washing up dishes (manually) Shower (number of showers) Lot D (4 occupants)b Clothes washing (number of loads) Dishwasher Washing up dishes (manually) Shower (number of showers) a b

Monday

Tuesday

Wednesday

Thursday

Friday

Saturday

Sunday

0 0 Yes 2

0 Yes Yes 2

0 0 Yes 2

0 0 Yes 2

0 0 Yes 2

3 Yes Yes 2

5 0 Yes 2

0 0 0 2

1 0 0 2

0 Yes 0 2

0 0 0 2

0 0 0 2

1 Yes Yes 2

1 0 0 2

2 Yes Yes 6

2 0 Yes 6

1 Yes Yes 6

0 0 Yes 8

1 Yes Yes 8

2 0 Yes 9

2 Yes Yes 5

1 0 Yes 3

0 0 Yes 3

1 Yes Yes 3

2 0 Yes 3

1 0 Yes 3

0 Yes Yes 3

1 0 Yes 3

Change of ownership during study with 2 occupants at the start (for the survey) but four occupants at the end. New addition to the household during the study.

C (Table 1) is reflected in this lot having the highest number of showers (Table 2). The bathroom/shower is one of the highest water use areas in any household, utilising greater than 25% of all household water use (Beal et al., 2011; Widiastuti et al., 2008; Roesner et al., 2006; Christova-Boal et al., 1996). This leads to lot C generating the largest volume of greywater. Furthermore, lot C has a higher frequency of dishwashing (both manual and machine) and kitchen waste water carries some of the highest levels of pollutants like phosphorus (Stevens et al., 2011a; Lanfax Laboratories, 2009; Misra and Sivongxay, 2009). Households used a diverse range of products especially for washing clothes (Table 3). Both lots A and B used a low-P product with approximately 1–2 mg L − 1 P, lot C used a product with a concentration of approximately 45–55 mg L − 1 P and lot D used a product with approximately 75 mg L − 1P (Lanfax Laboratories, 2009). The allowable loading of P is the cumulative quantity of P applied in the greywater that raises the soil solution P concentration to the maximum allowable value. At equilibrium, the soil solution P concentration will equal the P concentration in the applied greywater. When lots use high P containing products equilibrium in the soil can to be reached quickly, thus allowing movements of P to the surrounding environment. Residents of each lot were questioned about their knowledge of water efficiency and their understanding of greywater sustainability (Table 3). As this interview was conducted during a prolonged drought, each resident was keenly aware of the need for water efficiency and how to achieve it. Occupants of lot A had recently moved in (approximately 4 months prior) and the previous resident was

not able to be interviewed. Occupants of lot B showed the most understanding of greywater sustainability and the impacts of the irrigation. Occupants of lot C had knowledge of greywater sustainability, but due to the household demographic they were not able to, or unwilling to, apply that knowledge to greywater irrigation. Therefore this lot was likely to be the least sustainable. The occupants of lot D had knowledge of greywater sustainability but did not know the full impacts of each of the products they used. 3.2. Greywater quality Between 11 and 15 individual samples of greywater from each irrigated lot were analysed for pH, EC, SAR, Ca, Mg, Na, K, TN and TP, with a total of 51 samples analysed for the study site. Results are shown in Table 4 for lot A, Table 5 for lot B, Table 6 for lot C and Table 7 for lot D. A summary of all samples is shown in Table 8. The pH of the greywater for each of the four irrigated lots ranged between 5.7 and 10.3 (Table 8) with the average pH for lots A, B and D lying between 7.3 and 7.6 whereas lot C had an average pH of 8.7. The EC of the greywater had a similar pattern as pH, with lots A, B and D having similar conductivities (Table 8), whereas lot C was significantly higher with an average of 1240 μS cm −1 and a maximum of 2510 μS cm −1. The high EC of lot C is attributed to the use of a front loader washer — as this type of water efficient washing machine generates more concentrated greywater. Even though lot C utilised the most water (Table 1) the EC still remains high. This is in contrast to the expectations of dilution effects. The high EC is most probably a result in the high number of washing cycles and products used in the household.

Table 3 Household product use (indicating low P equating to less than 1 g per wash (Lanfax Laboratories, 2009)). Activity

Lot A product name

Lot B product name

Lot C product name

Lot D product name

Clothes washing liquid or powder Clothes washing fabric softener Clothes washing prewash treatment (bleach, enzyme, brightener) Dishwasher liquid, powder, tablet Dishwasher clearing agent (sparkle) Dishwashing liquid Water efficiency Greywater sustainability

Green care (low P) Cuddly Oxy advanced powder

Surf & duo-matic front-loader (high P) Fluffy ultra Napisan

Cold power liquid advanced lemon (high P) Nil Napisan

Finish Finish

Biozet (low P) Fluffy Sard oxy plus spray & napisan oxyaction max Coles dishwashing powder Unknown

Finish powerball Nil

Finish powerball Nil

Earth choice Yes Unknown

Earth choice Yes Yes

Sunlight & trix No No

Palmolive — antibacterial Yes Yes

292

R.D.R. Turner et al. / Science of the Total Environment 456–457 (2013) 287–298

Table 4 Greywater quality lot A. General greywater chemistry Lot A

pH

Electrical conductivity μS cm−1

Sodium adsorption ratio

Calcium (soluble) as Ca mg L−1

Magnesium (soluble) as Mg mg L−1

Sodium (soluble) as Na mg L−1

Potassium (soluble) as K mg L−1

Total nitrogen mg L−1

Total phosphorus mg L−1

No. of observations Minimum Maximum Median Mean Lower 95% confidence interval Upper 95% confidence interval

15 5.7 9.7 7.4 7.6 7.0 8.2

15 53 1242 315 378 220 535

13 1.0 38 9.9 11 4.8 17

15 1.0 9.6 3.0 4.2 2.6 5.8

15 0.3 4.5 1.2 1.4 0.8 2.0

15 6.9 320 65 86 44 129

12 1.1 27 6.4 8.0 3.8 12

15 1.9 43 8.6 9.9 4.4 15

15 0.3 45 3.8 12 4.1 20

The source water for each household is largely rain water (conductivity averaging 10 μS cm −1) and as such the conductivity of the greywater is a true representation of chemical composition of the products used by each household. The pattern of SAR between the lots is slightly different. Lots A and B had averages of 11 and 12, respectively and lot D had the lowest average of 6.2, whilst lot C had the highest average SAR of 35 as well as the highest maximum SAR value of 78. These differences are likely due to the relative proportions of the cations (Ca, Mg, Na and K) contained in the household products. Yet again, the elevated SAR for lot C is most probably a result of the high number of washing cycles and the composition of the products used by this household. When soils are irrigated with high SAR water the soil structure starts to degrade because of increased sodium exchange on the clay, resulting in reduced permeability (Misra and Sivongxay, 2009; Dawes and Goonetilleke, 2006; Dawes et al., 2005). Furthermore, if the degradation results in sodic soils this can change the sites hydrology leading to reduced infiltration through the soil profile and an increase of surface runoff and soil erosion (Dawes et al., 2005). This erosion could further increase the availability of P to surface water that would be amplified by the steep nature of the site and its close location to Enoggera Creek. Potential water eutrophication could occur, demonstrating non sustainable greywater irrigation. Differences in the total P concentration in the greywater of the four irrigated lots (Tables 4 to 7) are reflected by the P concentrations of household products. The average P concentration in greywater increased in the order lot B, lot A, lot D and finally lot C with values of

4.1, 12.1, 16.7 and 25.4 mg L−1, respectively and this trend is in agreement with results presented in Table 3. Furthermore lot D used the highest P containing product, which could produce greywater from the laundry of approximately 75 mg L −1 P whilst the maximum recorded P concentrations from lot D wag 65 mg L −1. Lot C had the highest concentration of soil P in the transpiration zone, due to irrigation with the highest volume and the high P concentration in the greywater. Therefore there are potential environmental impacts from lot C as a result of greywater irrigation and the transpiration zone might have long term sustainability issues. Lot C adheres to all aspects of the “Queensland Plumbing and Wastewater Code 2007” and the Plumbing and Drainage Act 2002 that relate to greywater. It has almost twice the recommended irrigation area, (200 m 2 vs. a recommended 108 m 2) and at 65 L person − 1 day − 1 generates substantially less than the recommended maximum of 95 L person − 1 day − 1 (Table 1). Yet the potential phosphorus loading (for which there are no legislative guidelines) is extreme at this site. There is a high risk of environmental impacts and limited long-term irrigation sustainability. These results illustrate that the legislation has gaps in not specifying sustainable greywater irrigation practices and instead just focuses on human health issues. The pH, EC, SAR, TKN and TP of the greywater from the current study were compared to other Australian greywater studies (Stevens et al., 2011a; Beal et al., 2008; Diaper et al., 2008; Christova-Boal et al., 1996) and appropriate Australian guidelines (Environment Protection

Table 5 Greywater quality lot B. General greywater chemistry Lot B

pH

Electrical conductivity μS cm−1

Sodium adsorption ratio

Calcium (soluble) as Ca mg L−1

Magnesium (soluble) as Mg mg L−1

Sodium (soluble) as Na mg L−1

Potassium (soluble) as K mg L−1

Total nitrogen mg L−1

Total phosphorus mg L−1

No. of observations Minimum Maximum Median Mean Lower 95% confidence interval Upper 95% confidence interval

11 6.4 9.8 7.1 7.5 6.7 8.3

11 98 1043 268 413 188 639

11 2.2 43 4.5 12 2.4 21

11 1.0 14 1.7 3.9 0.9 6.8

11 0.5 1.5 0.8 0.8 0.6 1.1

11 15 230 43 79 26 132

11 6.0 50 11 13 5.4 22

11 1.2 35 13 15 7.1 23

11 0.8 13 3.2 4.1 1.8 6.3

General greywater chemistry Lot C

pH

Electrical conductivity μS cm−1

Sodium adsorption Ratio

Calcium (soluble) as Ca mg L−1

Magnesium (soluble) as Mg mg L−1

Sodium (soluble) as Na mg L−1

Potassium (soluble) as K mg L−1

Total nitrogen mg L−1

Total phosphorus mg L−1

No. of observations Minimum Maximum Median Mean Lower 95% confidence interval Upper 95% confidence interval

11 5.8 10.3 9.5 8.7 7.7 9.8

11 112 2511 1108 1239 714 1765

11 4.9 78 29 35 18 53

11 1.0 8.5 3.2 4.2 2.4 6.0

11 0.5 1.7 1.0 1.0 0.8 1.2

11 24.0 630 260 287 157 418

11 6.0 16 8.0 9.0 6.7 11

11 11 36 15 18 13 23

11 3.4 49 28 25 13 37

Table 6 Greywater quality lot C.

R.D.R. Turner et al. / Science of the Total Environment 456–457 (2013) 287–298

293

Table 7 Greywater quality lot D. General greywater chemistry Lot D

pH

Electrical conductivity μS cm−1

Sodium adsorption ratio

Calcium (soluble) as Ca mg L−1

Magnesium (soluble) as Mg mg L−1

Sodium (soluble) as Na mg L−1

Potassium (soluble) as K mg L−1

Total nitrogen mg L−1

Total phosphorus mg L−1

No. of observations Minimum Maximum Median Mean Lower 95% confidence interval Upper 95% confidence interval

14 6.3 8.6 7.2 7.3 6.9 7.6

14 96 1635 357 451 240 662

9 1.4 12 5.8 6.2 3.1 9.3

14 1.6 13 7.5 7.4 4.9 9.8

14 0.5 6.3 2.6 2.9 1.7 4.0

14 12 150 56 64 40 88

12 3.2 20 6.2 8.1 5.1 11

14 0.0 12 9.7 8.1 5.8 10

14 1.4 65 12 16 5.5 27

and Heritage Council, 2006) (Table 9). Christova-Boal et al. (1996) investigated physical, chemical and microbiological parameters of greywater reuse for urban residential properties in Melbourne to determine environmental risks associated with reuse. Beal et al. (2008) previously measured greywater composition at the same study site as the present study. Diaper et al. (2008) developed a greywater testing protocol for Australian laboratories and their study specified synthetic greywater to test greywater treatment systems. Stevens et al. (2011a) assessed the environmental risks to Australian and New Zealand ecosystems from laundry detergents associated with greywater irrigation in gardens (Table 9). The “National guidelines for water recycling” (NGWR) (Environment Protection and Heritage Council, 2006) provide guidelines that focus on greywater uses for residential garden watering, car washing, toilet flushing, clothes washing, irrigation for urban recreational and open space in Australia. The values from the present study are largely consistent with the data from the previous Australian studies and guidelines, consequently they could be utilised in bolstering scientific information which underpins current legislation and guidelines. 3.3. Soil profiles To understand the soil conditions in each lot and to permit comparisons of the chemical and physical nature of the soils between each lot as well as comparisons to the non-irrigated control soils, soil depth profile

graphs are presented in Figs. 2 to 5 for pH, EC, Colwell P and PBI, respectively. Further to this, Colwell P results were assessed statistically to compare differences between the irrigated transpiration zones and the control sites. The soil pH of all the irrigated lots have increased compared to the non-irrigated controls (Fig. 2), except for lot D at depths greater than 0.2 m. This pH increase is most likely due to the presence of alkaline detergents and other household products in greywater. The alkaline greywater in this instance is improving soil pH (water) from an acidic range of 5.4–5.8 to 5.9–6.7, as optimal soil fertility occurs at a pH of 6.0 to 7.0 (Clancy, 2006). The increase of pH is likely due to basic cations, particularly Na displacing acidic cations (H, Al) from the exchange surfaces in the soil. The greywater cation concentrations shown in Tables 4 to 8 are generally low compared to “National guidelines for water recycling” (Environment Protection and Heritage Council, 2006). Thus the irrigation cation loadings will be lower, helping lengthen the sustainability of the transpiration zone in terms of soil pH and salinity (EC). Generally, the soil pH of each lot decreased and approached the non-irrigated control values with increasing depth (Fig. 2). This confirms that the cation additions through cation exchange are increasing soils pH (water). Given the acidic nature of the nonirrigated control soil, the addition of alkaline greywater to the transpiration zones appears to be sustainable. In terms of pH as long as future irrigation does not elevate soil pH towards alkaline conditions

Table 8 Greywater quality for all lots. General greywater chemistry All Lots pH

No. of observations Minimum Maximum Median Mean Lower 95% confidence interval Upper 95% confidence interval

Electrical Sodium Calcium Magnesium Sodium (soluble) Potassium Total Total conductivity adsorption ratio (soluble) as Ca mg L−1 (soluble) as as Na mg L−1 (soluble) as nitrogen phosphorus μS cm−1 Mg mg L−1 K mg L−1 mg L−1 mg L−1

51 51 5.7 53 10.3 2511 7.3 421 7.7 591 7.4 432 8.1 751

44 1.0 78 9.1 16 10 22

51 1.0 14 3.4 5.0 3.9 6.1

51 0.3 6.3 1.0 1.6 1.2 2.0

51 6.9 630 65 122 83 160

46 1.1 50 7.9 9.7 7.4 11

51 b0.1 43 11 12 9.8 15

51 0.3 65 5.1 14 9.8 19

Table 9 Greywater composition compared with results from other studies. Parameter

This study Payne Road Christova-Boal et al. Environment Protection Beal et al. (1996)a and Heritage Council (2006) (2008)

pH 7.0–7.4 Conductivity (μS/cm) 53–640 Sodium adsorption ratio 4–12 Total Kjeldahl nitrogen as N (mg L−1) 1.2–16 Total phosphorus as P (mg L−1) 0.3–5.1 a b c d

6.4–10 82–1400 0.9–32d 1.0–40 0.06–42

Combination of bathroom and laundry water sources. Water source is laundry only and range is 5th to 95th percentile. Synthetic greywater derived in a laboratory. Calculated not published.

5.0–10.0 80–1300 0.79–32 0.06–50 0.04–42

5.4–10.3 260–2500 2–79 0.1–43 1.8–65

Diaper et al. Stevens et al. (2011a, 2011b) b (2008) 6.5–8.0c 300–400 NR 3.0–5.0 10–20

10.4–11.1 950–6700 55–379 NR b1–245

294

R.D.R. Turner et al. / Science of the Total Environment 456–457 (2013) 287–298

Fig. 2. Depth profile for pH for each lot and non-irrigated control sites (the averaged concentration data have been plotted for the midpoint of each 100 mm depth interval).

(greater than 7.5 pH units) the current levels of greywater irrigation should have minimal impacts and therefore can be considered sustainable. The EC of lot C is higher than the other three lots at all depths which can be linked to the markedly high levels of sodium salts in its greywater (Table 6). Generally, with increasing depth the EC decreased and approached the values of the non-irrigated control sites. The data are generally not consistent with that in the literature, which tends to show high EC levels in soils irrigated with greywater (Howard et al., 2007; Namdarian, 2007). The overriding reason for this is the fact that the source water for these lots is rain water (low starting EC as previously stated), furthermore the addition of salts (K+, Ca+, Mg+ and Na +) from greywater irrigation is lower (Tables 4 to 8). There is minimal salt loading from greywater on the individual soil profiles as seen in the soil EC profile (Fig. 3). Statistical assessments of Colwell P results were performed to determine if there were differences between the non-irrigated control sites and irrigated lots. The Colwell P results were not normally distributed and all attempts to transform the data to apply parametric statistical

analysis were not successful. Therefore a non-parametric method was selected. The Kruskal–Wallis test was applied to the Colwell P results of each lot in comparison to control sites. A Bonferroni corrected significance p level of 0.005 was used. The p values for lot A (0.004) and lot C (b 0.0001) showed significant differences between their transpiration zones and the control sites. Whereas lot B (0.100) and D (0.092) p values were not significantly different from the controls. The concentration of Colwell P is shown in Fig. 4 for the irrigated and non-irrigated control soil profiles. In the soil surface (0.0 to 0.1 m) Colwell P concentrations followed the order, lot C > A > D >> B. The Colwell P concentrations of lot B are low, even lower than the non-irrigated lots. This could be a result of the location of lot B compared to the other three lots (lot B is on a slightly different ridge, Fig. 1). The Colwell P concentrations of lots A, C and D all were greater than for the non-irrigated soils. In general, Colwell P concentrations decreased with increasing depth, apart from lot B which remained essentially unchanged. At a depth of 0.3 to 0.4 m the Colwell P levels for all irrigated lots, except lot C, converged to similar concentrations to the non-irrigated soils, demonstrating that the movement of the irrigated

Fig. 3. Depth profile for; electrical conductivity (dS m−1) for each lot and non-irrigated control sites (the averaged concentration data have been plotted for the midpoint of each 100 mm depth interval).

R.D.R. Turner et al. / Science of the Total Environment 456–457 (2013) 287–298

295

Fig. 4. Depth profile for Colwell extractable phosphorus (mg kg−1) for each lot and non-irrigated control sites (the averaged concentration data have been plotted for the midpoint of each 100 mm depth interval).

phosphorus is being bound by the soil. Irrespective of depth, the Colwell P concentration of lot C remained greater than that of the non-irrigated soils. Fig. 4 confirms the values presented in Tables 4 to 7, with lots, A, B and D having markedly lower median total P concentrations in greywater than lot C. With excessive P concentrations plant growth can be inhibited. With soils having a pH less than 7 (as seen in Fig. 2) excessive phosphorus can lead to iron deficiency (Moody and Bolland, 1999). Furthermore the Queensland Department of Primary Industries and Fisheries states that Colwell P concentrations should not exceed 150 mg kg−1 because of the risk of offsite P movement (Pattison et al., 2010) via soil erosion. In light of these findings, it is evident that the current levels of irrigated P in the greywater (with an average range of 5–65 mg L −1) and the high Colwell P concentration already in the soil (with an average range of 2–620 mg kg−1) raises questions over the long-term sustainability of the whole development. To explore this sustainability there is a need to investigate whether soils still have the capacity to adsorb irrigated phosphorus. To assess this, details of the soil's Phosphorus Buffering Index (PBI) for each lot as well as the non-irrigated control sites are shown in Fig. 5.

In Fig. 5, the PBI of all irrigated lots has decreased compared to the non-irrigated soils. The current PBI capacity of lots A, B and D are less than 110. It is fortuitous that lot C has the highest PBI capacity (of the irrigated lots) as it also has the greywater with the highest average phosphorus concentration (Table 6). This could support the adsorption of some of the high concentrations of P in the future, potentially lengthening the transpiration zones sustainability. As the PBI of all studied soils are low to moderate according to the PBI categories of Moody and Bolland (1999), further efforts towards sustainable greywater irrigation are required to assist with the low P sorption capacity of the soil. To achieve this, all lots should consider using or continuing to use low phosphorus containing household products, especially lots C and D. 3.4. Phosphorus irrigation sustainability To evaluate the sustainability of the transpiration zone and the potential environmental impact we need to review Tables 10 and 11. The two tables evaluate each 100 mm soil horizon in relation to the soil’s ability to adsorb P and subsequently the potential P loss to the

Fig. 5. Depth profile for Phosphorus Buffering Index (PBI) for each lot and non-irrigated control sites (the averaged concentration data have been plotted for the midpoint of each 100 mm depth interval).

296

R.D.R. Turner et al. / Science of the Total Environment 456–457 (2013) 287–298

Table 10 Phosphorus irrigation sustainability using the Mehlich3 phosphorus saturation ratio (M3PSR); values with ✘ indicate significant phosphorus leaching risk; values with ! indicate environmental concern with regards to phosphorus leaching; values with ✓ indicate no environmental concern due to phosphorus leaching. Depth (m)

Lot A

0.1 0.2 0.3 0.4 0.5

0.71 0.37 0.11 0.06 0.05

Lot B 0.03 0.02 0.03 0.03 0.01

Lot C

Lot D

0.47 0.28 0.15 0.11 0.07

Average

0.14 0.05 0.02 0.01 0.01

0.32 0.19 0.08 0.06 0.04

Non irrigated 0.07 0.05 0.03 0.02 0.01

Table 11 Colwell P and PBI ratio values, down to 0.5 m depth for each lot and non-irrigated control sites (Colwell P and phosphorus buffing index ratio greater than 2.00 could lead to loss of phosphorus to the environment, whereas ratios less than 2.0 pose a possible environmental risk). Depth (m)

Lot A

Lot B

Lot C

Lot D

Average

Non irrigated

0.1 0.2 0.3 0.4 0.5

3.42 2.02 0.74 0.45 0.32

0.30 0.23 0.28 0.29 0.12

2.96 2.38 1.40 1.08 0.95

1.60 1.00 0.56 0.29 0.26

2.28 1.56 0.82 0.60 0.49

0.73 0.49 0.32 0.20 0.10

environment from further irrigation and consequently the sites sustainability. At the surface (0–0.1 m) the M3PSR values (Table 10) for lots A and C displayed a high risk of off-site P movement (M3PSR values greater than 0.2). Lot D had M3PSR values (0.10–0.15) that indicated that leaching was of environmental concern whereas lot B displayed similar results to the non-irrigated control (0.03 and 0.07 respectively). As the soil depth approached 0.5 m the M3PSR values from irrigated lots converged with the non-irrigated soil values. Irrigating greywater onto the surface soil (Table 11) in lots A and C poses a significant environmental P risk (i.e. a PERI value greater than 2.0 could lead to loss of P to the environment). Lot D had PERI values that were not of environmental risk (i.e., b2.0), whereas lot B posed a similar risk to that for the non-irrigated soils (0.30 and 0.73 respectively). Irrigating greywater to the transpiration zones at lots A and C and lot D needs to be managed to avoid reaching a 2.0 risk level. As some irrigated lots are no longer sustainable questions should be asked. Has there been an impact from surface water runoff on Enoggera Creek? Is the perched groundwater contaminated? It appears that in Tables 10 and 11 the saturated P surface layers could cause preferential movement of P into both surface water and through the soil profile, thus potentially intercepting the groundwater and/or Enoggera Creek.

3.5. Phosphorus loading comparison Beal et al. (2008) previously qualitatively compared the long-term irrigation sustainability of lots A to D. Beal et al. (2008) research showed the average P loading to the transpiration zones from irrigation was between 54 and 127 kg ha − 1 yr − 1. They also noted that soil samples should be analysed to confirm the above findings. With a

further two years of irrigation and further greywater analysis this study has been able to update the Beal et al. (2008) data (Table 12). With further and more comprehensive research, the phosphorus loading range became more dynamic and varied. This revised phosphorus loading of 10 to 180 kg ha−1 yr−1 for the four lots was observed with a potential maximum application of phosphorus of 350 kg ha−1 yr−1. Crush and Rowarth (2007) stated that commercial P fertiliser application rates (pasture fertilisation) are about 30 kg P ha − 1 yr − 1 for turfgrasses, which is exceeded by the mean values for lots A, C and D, whereas (Vieritz et al., 2003) demonstrated an optimal uptake of 100 kg P ha − 1 yr − 1 from grass, which is only exceeded by lot C. The potential maximum P load exceeds the 30 kg ha − 1 yr − 1 of commercial pasture fertiliser practices by tenfold and also exceeds the 100 kg P ha − 1 yr − 1 maximum for grass uptake by three-fold demonstrating that significant P is being applied that can't be used by plant uptake. It is possible that P could be transported to nearby waterways. In contrast, the lot B upper 95% confidence interval for P loading is 16 kg ha −1 yr −1, which is much less than commercial pasture fertiliser application rates. As most of the transpirations zones are turfed there is the potential for excessive phosphorus loading on the soil from lots A, C and D. To enhance the sustainability of these transpiration zones simple steps could be taken (e.g. changes of washing products and through education) to prevent any long-term environmental impact. The theoretical loads of P from the irrigation water were compared to the actual Colwell P phosphorus concentrations in the soil samples. This comparison was limited to a depth of 0.4 m (Table 13) as below this the non-irrigated soils were equal to or slightly greater than the irrigated lots. The increase in Colwell P for each soil profile is clearly of similar proportions to that of the irrigated P loads. Again lot C displays higher results for estimated P loads, with lots A and D being comparable to each other. Lot B had significantly lower estimated P loads. Future sustainability can be assessed by doubling the exposure time (irrigation volumes GW Load P kg ha −1”) approximately another four years of irrigation to estimate potential “Soil Colwell P kg ha −1” concentrations. Lot A is estimated to have Colwell P levels of 539 kg ha −1; lot B 63 kg ha −1, lot C 1119 kg ha −1, lot D 669 kg ha −1. At these current rates of irrigation based on the M3PSR and PERI, and potential utilisation by plants there appears limited sustainability for lot C and some concern for lots A and D. This sustained level of irrigation could cause substantial impacts from P to the surrounding environment. 4. Conclusions In assessing the sustainability of greywater irrigation, the data clearly show benefits regarding water reuse, as the four irrigated lots collectively reduced the use of 1.6 million litres of potable water over four years. The sustainability of greywater irrigation applied to transpiration zones is variable. Two lots (A and C) displayed a significant risk of phosphorus interacting with the surrounding environment and therefore have limited sustainability. It was demonstrated that one lot (D) showed levels of phosphorus that was of environmental concern but with careful management it could be

Table 12 Theoretical phosphorus (P) loading rates to irrigation area. Lot

No. days of irrigation

Years of irrigation

Mean P load (kg ha−1 yr−1)

Lower 95% CI for P load (kg ha−1 yr−1)

Upper 95% CI for P load (kg ha−1 yr−1)

Maximum P load (kg ha−1 yr−1)

A B C D

1678 1284 1255 1561

4.60 3.52 3.44 4.28

63 10 180 85

21 4 93 28

105 16 268 142

234 32 347 329

R.D.R. Turner et al. / Science of the Total Environment 456–457 (2013) 287–298 Table 13 Phosphorus (P) loading comparison (soil Colwell P kg ha−1 = total Colwell P − nonirrigated Colwell P per 100 mm horizon totaling 0.0 to 0.4 m, estimated GW loads (P) are calculated from actual greywater irrigation concentrations). Lot

Soil Colwell P kg ha−1

Estimated GW load P kg ha−1 for the irrigation period (CI 5%– × – CI 5%)

A B C D

425 b1 769 105

91–269–448 14–32–49 288–560–831 110–334–558

considered sustainable. Whereas another lot (B) displayed phosphorus leaching risk similar to that of the non-irrigated control soils and hence indicates sustainable greywater irrigation. The potential of phosphorus interacting with the surrounding environment was demonstrated by M3PSR and PERI and these have proved to be useful surrogates for determining long-term phosphorus loadings in irrigated soils. There is a possible lack of understanding or willingness by the residents to connect how their household products are associated with the water quality of greywater and its impact on soil. This is not helped by the fact there is still no holistic desire by industry and community to produce or use low-level phosphorus products. Additionally, if current guidelines and legislation contained adequate guidelines on phosphorus irrigation loadings, the situation with lots A and C could be avoided, and that of lot D successfully managed. Education programs could encourage residents to understand the impact of household products on greywater composition and actively maintain and minimise their environmental footprint. This would assist in the sustainable outcomes for greywater irrigation. Households can utilise greywater appropriately and with better education and legislation other households could achieve similar outcomes. The reported phosphorus soil concentrations and the estimated greywater loadings were of similar magnitude, however more sophisticated irrigation assessment models such as MEDLI could be enhanced to estimate greywater loadings by including this sub-surface irrigation data, which in turn would help future sub-surface greywater irrigation schemes having less environmental impact. The results from lot B clearly demonstrate that with knowledge, appropriate household product use and responsible use of greywater. Greywater irrigation can significantly reduce the phosphorus load thus significantly reducing environmental risk. Greywater irrigation can thus be practiced sustainably. Conflict of Interest There is no conflict of interest. Acknowledgments The authors would also like to acknowledge the Queensland Government for providing Ryan D.R. Turner with study time and funding this research project, we particularly would like to thank the staff at the Environment and Resource Sciences Chemistry Centre for their time and assistance. Thanks to colleagues at the Queensland Government who provided, valuable advice and support. In particular, I would like to thank Dr Michael Warne, Ms Julie Ivison, Mr Robert DeHayr and Mr Barry Hood. This research would not have been possible without the support of the residents at Payne Road the Gap, Queensland. Appendix A. Supplementary data Supplementary data associated with this article can be found in the online version, at http://dx.doi.org/10.1016/j.scitotenv.2013.01.088. These data include Google maps of the most important areas described in this article.

297

References Al-Jayyousi OR. Greywater reuse: towards sustainable water management. Desalination 2003;156(1–3):181–92. Avvannavar SM, Mani M. Guidelines for the safe use of wastewater, excreta and greywater, Volume 3: wastewater and excreta use in aquaculture, 2006, WHO, 20, Avenue Appia, 1211, Geneva, 27 Switzerland, 92-4-154684-0 (V 3), US $ 45.00, 158. Sci. Total. Environ. 2007;382(2–3):391–2. Barton L, Schipper LA, Barkle GF, McLeod M, Speir TW, Taylor MD, et al. Land application of domestic effluent onto four soil types: plant uptake and nutrient leaching. J. Environ. Qual. 2005;34(2):635–43. Beal C, Hood B, Gardner E, Lane J, Christiansen C. Energy and Water Metabolism of a Sustainable Subdivision in South East Qld: A Reality Check. Enviro’08 Melbourne; 2008 [Presented at, 5–7 May 2008]. Beal C, Stewart R, Huang T, Rey E. SEQ residential end use study. Aust. Water Assoc. J. 2011;38(1):80–4. Biolytix. "Global winner, Biolytix, is taking on effluent society", 2005, Ecos. Brisbane City Council, 2010, Know your creek-Breakfast-Enoggera Creek, Brisbane. 127; 2005. p. 5. Brisbane City Council. Know your creek-Breakfast-Enoggera Creek. Brisbane: Brisbane City Council; 2010. Christova-Boal D, Eden RE, McFarlane S. An investigation into greywater reuse for urban residential properties. Desalination 1996;106(1–3):391–7. Clancy K. 26/02/2006-last update, Managing soil pH for optimum turf quality [Homepage of Fusion Turf Nutrition], [Online]. Available: http://www.fusionfert. com/itn/articles/ph.pdf. [2012, October/20]. Crush JR, Rowarth JS. The role of C4 grasses in New Zealand pastoral systems. N. Z. J. Agric. Res. 2007;50(2):125–37. Dawes L, Goonetilleke A. Using undisturbed columns to predict long term behaviour of effluent irrigated soils under field conditions. Aust. J. Soil Res. 2006;44(7):661–76. Dawes L, Goonetilleke A, Cox M. Assessment of physical and chemical attributes of sub-tropical soil to predict long term effluent treatment potential. Soil Sediment Contam. 2005;14(3):211–29. de Mesquita Filho MV, Torrent J. Phosphate sorption as related to mineralogy of a hydrosequence of soils from the Cerrado region (Brazil). Geoderma 1993;58(1–2): 107–23. Department of State Development, Infrastructure, Planning (DIP). The Queensland Plumbing and Wastewater Code (QPW code). Compliance ed. Queensland, Australia, Brisbane: Department of State Development, Infrastructure and Planning (DIP); 2007. Diaper C, Toifl M, Storey M. Greywater technology testing protocol. CSIRO Water for a Healthy Country National Research Flagship report CSIRO, Australia; 2008. Eaton AD, Clesceri LS, Rice EF, Greenberg AE, Franson MAH. Standard methods for the examination of water & wastewater. 21st ed. Washington D.C.: American Public Health Association; 2005 Environment Protection and Heritage Council. National guidelines for water recycling. Managing health and environmental risks (phase 1). Canberra: Environment Protection and Heritage Council (EPHC); 2006. Eriksson E, Donner E. Metals in greywater: sources, presence and removal efficiencies. Desalination 2009;248(1–3):271–8. Gardner T, Vieritz A, Atzeni M. Model for effluent disposal using land irrigation (MEDLI). Version 2.0 ed. Brisbane: Queensland Department of Primary Industries and the Queensland Department of Natural Resources; 2002. Godfrey S, Labhasetwar P, Wate S. Greywater reuse in residential schools in Madhya Pradesh, India — a case study of cost–benefit analysis. Resour. Conserv. Recycl. 2009;53(5):287–93. Greysmart [homepage of GreySmart]. [Online]. Available:http://www.savewater.com. au/how-to-save-water/in-the-home/greysmart. [4/10/2012]. Gross A, Azulai N, Oron G, Ronen Z, Arnold M, Nejidat A. Environmental impact and health risks associated with greywater irrigation: a case study. Water Sci. Technol. 2005;52(8):161–9. Gross A, Kaplan D, Baker K. Removal of chemical and microbiological contaminants from domestic greywater using a recycled vertical flow bioreactor (RVFB). Ecol. Eng. 2007;31(2):107–14. Hammond AL. Phosphate replacements: problems with the washday miracle. Science 1971;172(3981):361–3. Howard E, Misra R, Loch R, Le MN. Laundry grey water potential impact on Toowoomba soils — final report. Toowoomba, Australia: University of Southern Queensland, National Centre for Engineering in Agriculture; 2007. Jenkins D, Kaufman WJ, McGauhey PH, Horne AJ, Gasser J. Environmental impact of detergent builders in California waters. Water Res. 1973;7(1–2):265–81. Jeppesen B. Domestic greywater re-use: Australia's challenge for the future. Desalination 1996;106(1–3):311–5. Johnson D. Calculating soil c and nutrient contents. Reno, NV 89557: Department of Environmental and Resource Sciences University of Nevada; 2012 [[Online]. Available: http://www.ag.unr.edu/dwj, [4/1/2012]]. Jury WA, Vaux HJ. Advances in agronomy volume 95. The emerging global water crisis: managing scarcity and conflict between water users, vol. 95. ; 2007. p. 1-76. Kaus R. Accreditation — ISO/IEC 17025. Berlin Heidelberg: Springer; 2010. Khalil WA, Goonetilleke A, Kokot S, Carroll S. Use of chemometrics methods and multicriteria decision-making for site selection for sustainable on-site sewage effluent disposal. Anal. Chim. Acta 2004;506(1):41–56. Knud-Hansen C. Historical Perspecitve of the Phosphate Detergent Conflict. In: Knud-Hansen Chris, editor. Conflict research consortium. Colorado: University of Colorado; 1993. p. 94. Koopmans G. Soil phosphorus quantity–intensity relationships to predict increased soil phosphorus loss to overland and subsurface flow. Chemosphere 2002;48(7): 679–87.

298

R.D.R. Turner et al. / Science of the Total Environment 456–457 (2013) 287–298

Lanfax Laboratories. Laundry products research; 2009 [[Homepage of Lanfax], [Online]. Available: http://www.lanfaxlabs.com.au/laundry.htm [2012, 4/1/2012]]. Lewis D, Clarke A, Hall W. Factors affecting the retention of phosphorus applied as superphosphate to the sandy soils in south-eastern South Australia. Aust. J. Soil Res. 1981;19(2):167. Maguire RO, Sims JT. Soil testing to predict phosphorus leaching. J. Environ. Qual. 2002;31(5):1601–9. Maimon A, Tal A, Friedler E, Gross A. Safe on-site reuse of greywater for irrigation — a critical review of current guidelines. Environ. Sci. Technol. 2010;44(9):3213–20. March JG, Gual M. Studies on chlorination of greywater. Desalination 2009;249(1): 317–22. Misra RK, Sivongxay A. Reuse of laundry greywater as affected by its interaction with saturated soil. J. Hydrol. 2009;366(1–4):55–61. Moody PW. Environmental risk indicators for soil phosphorus status. Soil Res. 2011;49(3):247–52. Moody PW, Bolland MDA. Phosphorus. In: Peverill KI, Reuter DJ, Sparrow LA, editors. Soil analysis: an interpretation manual. 1st ed. Collingwood, Vic: CSIRO Publishing; 1999. p. 187–228. Namdarian F. The impact of greywater irrigation systems on domestic soil environments. Hunours ed. Melbourne: RMIT; 2007. Patterson, RA. A resident's role in minimising nitrogen, phosphorus and salt in domestic wastewater. A resident's role in minimising nitrogen, phosphorus and salt in domestic wastewater., ed. 749, Lanfax Laboratories, Armidale NSW Australia, March 21–24, 2004. pp. 740. Pattison T, Moody P, Bagshaw J. Soil health for vegetable production in Australia. 1st ed. Queensland: Department of Employment, Economic Development and Innovation; Primary industries & fisheries; Queensland Government; 2010. Peverill KI, Reuter DJ, Sparrow LA. Soil analysis: an interpretation manual. Collingwood, Vic: CSIRO Publishing; 1999. Pinto U, Maheshwari BL. Reuse of greywater for irrigation around homes in Australia: understanding community views, issues and practices. Urban Water J. 2010;7(2): 141–53. Queensland Urban Utilities. January 2012-last update, in the pipeline — Queensland urban utilities [homepage of Queensland urban utilities], [online]. Available: http://www. urbanutilities.com.au/your_home/Newsletters/January_2012/. [2012, 6/3/2012]. Rayment G, Lyons D. Soil chemical methods — Australasia. Melbourne: CSIRO Publishing; 2011. Regelsberger M, Baban A, Bouselmi L, Shafy HA, El Hamouri B. Zer0-M, sustainable concepts towards a zero outflow municipality. Desalination 2007;215(1–3):64–72. ReVelle P, ReVelle C. The environment: issues and choices for society. Boston: Jones and Bartlett Publishers; 1988. Roesner L, Qian Y, Criswell M, Stromberger M, Klein S. Longterm effects of landscape irrigation using household greywater — literature review and synthesis. Colorado: Water Environment Research Foundation and the Soap and Detergent Association; 2006. Sharpley AN. Soil phosphorus dynamics: agronomic and environmental impacts. Ecol. Eng. 1995;5(2–3):261–79.

Sharpley AN, Robinson JS, Smith SJ. Bioavailable phosphorus dynamics in agricultural soils and effects on water quality. Geoderma 1995;67(1–2):1-15. Sharpley A, Daniel TC, Sims JT, Pote DH. Determining environmentally sound soil phosphorus levels. March/AprilJ. Soil Water Conserv. 1996;51(2):160–6. Sims JT, Maguire RO, Leytem AB, Gartley KL, Pautler MC. Evaluation of Mehlich 3 as an agri-environmental soil phosphorus test for the Mid-Atlantic United States of America. Soil Sci. Soc. Am. J. 2002;66(6):2016–32. Sinclair Knight Merz. Cross river rail environmental impact statement — surface Water, Brisbane; 2011. Standards Australia. AS/NZS 5667.1:1998, Water quality — sampling — guidance on the design of sampling programs, sampling techniques and the preservation and handling of samples edn. Homebush NSW: Standards Australia; 1998a. Standards Australia. AS/NZS 5667.10:1998 Water quality: sampling. Part 10, Guidance on sampling of waste watersStandards Australia ed. ; 1998b [Homebush, NSW]. Standards Australia. AS 1289.3.6.3-2003 Methods of testing soils for engineering purposes — soil classification tests—determination of the particle size distribution of a soil—standard method of fine analysis using a hydrometer 2003. 2nd ed. Australia: Standards Australia; 2003. Stevens D, Dillon P, Page D, Warne SJ, Ying GG. Assessing environmental risks of laundry detergents in greywater used for irrigation. J. Water Reuse Desalin. 2011a;1(2): 61–77. Stevens D, Harris C, Hannaford J, Wilson S. The Greysmart ranking system for assessing household cleaning and personal care products that enter greywater used for irrigating gardens. Suite 204, 198 Docklands, Victoria: Atura Pty Ltd; 2011b. p. 3008. Thorburn P, Shaw R. Effects of different dispersion and fine fraction determination methods on the results of routine particle size analysis. Soil Res. 1987;25(4): 347–60. Travis MJ, Wiel-Shafran A, Weisbrod N, Adar E, Gross A. Greywater reuse for irrigation: effect on soil properties. Sci. Total. Environ. 2010;408(12):2501–8. Varian I. Varian vista pro operation manual 2001. 1st ed. Melbourne: Varian, Inc.; 2001. Vieritz A, Truong P, Gardner E, Smeal C. Modelling Monto vetiver growth and nutrient uptake for effluent irrigation schemes. MEDLI review ed. Queensland, Australia: Department of Natural Resources and Mines; 2003. Whitehead JH, Patterson RA. Assessing sustainable greywater reuse and application rates. In: Patterson RA, editor. Innovation and Technology for On-site Systems. Proceedings of On-site'07 conference. 25–27 September 2007Armidale: Lanfax Laboratories; 2007. p. 3. [25–27 September 2007]. Widiastuti N, Wu H, Ang M, Zhang D. The potential application of natural zeolite for greywater treatment. Desalination 2008;218(1–3):271–80. Wiel-Shafran A, Ronen Z, Weisbrod N, Adar E, Gross A. Potential changes in soil properties following irrigation with surfactant-rich greywater. Ecol. Eng. 2006;26(4): 348–54. Winward GP, Avery LM, Frazer-Williams R, Pidou M, Jeffrey P, Stephenson T, et al. A study of the microbial quality of grey water and an evaluation of treatment technologies for reuse. Ecol. Eng. 2008;32(2):187–97.