Liquid effluent treatment, sewage sludge management and industrial effluent standards

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Resources, Conservationand Recycling 16 (1996) 113-133

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Liquid effluent treatment, sewage sludge management and industrial effluent standards Uwe Stoll Environmental Engineering Program, Asian Institute of Technology, Bangkok, Thailand

Abstract

The paper gives a general and condensed overview on wastewater and sewage sludge management with information on wastewater/sludge characteristics, nature of pollution problems, basic steps of treatment and outlook on future demands. It includes further information on organization forms for wastewater-utility management and a discussion on appropriate effluent standards. Keywords: Wastewater; Sewage sludge; Utility management; Effluent standards

1. W a s t e w a t e r characteristics and related treatment processes

1.1.1, Wastewater characteristics

Wastewater is the product remaining of a source of fresh water after being used by a community for life support or manufacturing processes. A more detailed examination of wastewater provides for the definition of a wastewater by standard characteristics such as physical, chemical and biological. The physical characteristics include such items as temperature, odor and color of the waste. A characteristic of prime concern in wastewater is the type and concentration of solids contained in the flow stream. Another physical characteristic affecting the treatment processes for wastewater is the variation of flow that is experienced either on a d a y / n i g h t basis due to human life style or specific manufacturing processes. These variations are also affected by the day of the week, and the season of the year. The chemical characteristics affecting the treatment of wastewater include such things as the acidity or alkalinity of the waste stream, the types of minerals or mineral salts contained either in the original fresh water source or contributed as a waste product during the use of the fresh water, and the relative amounts of organic and inorganic 0921-3449/96/$15.00 © 1996 Elsevier Science B.V. All rights reserved SSDI 0921-3449(95)00050-X

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solids present. The distribution of organic and inorganic solids is normally the characteristic of most importance in determining treatment processes. These solids can occur either in suspension or dissolved in the liquid or solution. The solids that are in suspension are those most readily removed while the dissolved solids are the most difficult, and more expensive to remove from the wastewater stream. The third characteristic of wastewater pertains to the biological aspect of the waste. Normally, the wastewater stream transporting the human waste product in significant amounts carries with it a sufficient bacteria population that when provided the proper environmental conditions, such as pH value and temperature, the organic compounds are broken down to the basic constituents of water, carbon dioxide gas and inert ash. Significant amounts of industrial type of waste can provide an environment that hinders or inhibits the activity of the bacterial population in the waste stream. When such is the case, modifications of the basic treatment of the flow are normally required to provide for the adjustment to the proper environment.

1.1.2. Nature of pollution problems When a waste stream is discharged untreated into a receiving water body whether it be a river, lake or even a larger water body such as an ocean, certain actions take place which have a detrimental effect on the overall environmental conditions natural to the receiving water body requiring special treatment of the wastewater. The main effects are: carbon and ammonia removal causes oxygen consumption by the biological process which may lead to an oxygen deficiency causing anaerobic conditions (rot) in the river/lake. Once the anaerobic stage is reached in the life of the receiving river, it is considered to be 'dead' in that it is no longer in a fresh condition allowing the growth of aquatic life. Nutrients, mainly phosphorus and nitrogen, under proper conditions promote growth of undesirable plants and organisms such as algae. The growth of these organisms and plants further deplete the available oxygen in the receiving water body, and convert the river or lake from a fresh to a dead source of water very rapidly. Toxic substances destroy aquatic live. Hazardous substances such as heavy metals and organic pollutants cause changes and destroy of organisms over a medium term.

1.1.3. Basic steps of treatment Depending on the relative degree of pollution to be imposed in a stream, the process of treatment comprises the following basic steps: When sewage has been delivered, via the sewers, to the treatment works it is given primary treatment to remove the larger floating and suspended solid matter, grit and also much of the oil and grease content if present in an appreciable amount. Under normal circumstances primary treatment is considered to remove approx. 30 to 50% of the contaminates in the wastewater, The essential stages for primary treatment are: • Screening - the development of the state-of-the-art is going to fine screens with 3 mm to 8 mm bar space/slot opening in order to guarantee a safe operation and maintenance of the plant. • Grit removal - in grit tanks or aerated grit chambers.

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• Sedimentation - with or without mechanical or chemical flocculation. The retention time depends on the further treatment processes, such as nitrification/denitrification. In front of an extended aeration plant there is not primary sedimentation. Secondary treatment is normally applied in addition to primary treatment by means of biological methods and consists of those processes that are designed for the removal of dissolved compounds in the waste stream. The successful operation of a wastewater treatment plant using secondary treatment initially provides 80 to 98% removal of the pollutant load, depending on the wastewater characteristics. Biological treatment is normally carried out by one of the approved methods, biological filters, activated sludge plants or anaerobic digestion, which in reality are an artificial intensification and acceleration of the ordinary aerobic processes of natural purification that go on in rivers polluted by limited amounts of organic matter. Depending on the wastewater contents and the aims of treatment those primary processes can be modified and combined in various ways. In the aerobic biological purification of wastewater in the presence of sufficient air, bacteria and other microorganisms produce a number of changes, in the following order: • Coagulation stage - colloids and pseudo-colloids are flocculated and coagulated. • Carbonaceous oxidation stage - carbonaceous matter, especially that in solution, is oxidized to carbon dioxide. • Nitrogenous oxidation, or nitrification stage - ammonia, derived from the breakdown of nitrogenous organic matter, is oxidized to nitrite and nitrate. The classical processes of activated sludge treatment can be improved by certain modifications for: • Denitrification, derived from the biological breakdown of nitrate to nitrogen. • Biological phosphorus removal derived from the extended phosphorus uptake by the bacteria. In the anaerobic biological purification (anaerobic digestion) of wastewater, the waste is mixed with large quantities of bacteria and oxygen is excluded. Under these conditions, highly specialized bacteria grow, which convert the organics within four distinct phases into carbon dioxide and methane gas. Anaerobic digestion is widely used to treat high concentrated wastewaters because of anaerobic conversion yields relatively little energy. Thus, the rate of microbe growth is slow with only a small part of the waste converted to now cells, but as much as 80 to 90% of the degradable organics C H 4 gas and CO 2. This minimizes the problem of excess sludge disposal. Power needs are reduced because oxygen isn't required. In addition, the methane gas is a source of energy for heating or gas engine generation of electricity. Biological processes are in most applications combined with a secondary settlement in order to separate the biological sludge from the wastewater and to achieve a solids detention time independent of the hydraulic detention time. Tertiary treatment is a third process system that is normally applied to wastewater streams requiring the highest degree of removal of polluting solids together with the nutrients due to the extreme adverse affect that these would have on the receiving water body. Successful operation of tertiary treatment systems should provide as high as 99% removal of the pollutional solids together with 85 to 90% of the nutrient load in the wastewater stream.

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Methods of treatment are: • Nitrification and denitriflcation by biological treatment. • Phosphate precipitation. • Suspended solids removal by microstrainers or sand-filters. In the near and medium term future requirements for disinfection will be established, especially when effluents are discharged into lakes or rivers being used for potable water supply or touristic/water sport benefits. Methods o f treatment are: • Oxidation by ozone; • Ultra-violet radiation; • Ultra-filtration. Chemical treatment has wide applications in industrial wastewater treatment. The major treatment systems include: • Adsorption; • Coagulation; • Dialysis/electrodialysis; • Ion exchange; • Neutralization; • Oxidation/reduction; • Precipitation; • Membrane filtration - ultrafiltration/reverse osmosis. 1.1.4. Outlook on future demands

The enactment of recent regulations on effluent standards involves the more efficient elimination of carbonaceous pollution and suspended solids. Furthermore, nitrogen and phosphorous removal can be required. Treatment for hazardous substances such as heavy metals and organic pollutants is obligatory if concentrations exceed discharge limits. In the present state-of-the-art, only biological systems are capable of achieving the results required in acceptable economic conditions. In accordance with the specific requirements the biological systems have to be combined with physical and chemical processes. The interconnections between those processes have to be looked for carefully when designing a plant. The activated sludge system with diffused aeration will be the most used technology because it can be tailored to handle a wide variety of effluent requirements. The applications of tertiary treatment techniques - microstrainers and sand filtration - will increase in the near future. The application of disinfection of the effluent - ozone, UV, ultrafiltration - will increase in the medium term future.

2. S e w a g e sludge characteristics and related t r e a t m e n t processes 2.1.1. Sewage sludge characteristics

Purification of wastewater means first the removal or elimination of polluting matter. Safe disposal of the residues, i.e., disposal avoiding harm to the environment, is thus an

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integral part of wastewater treatment and water pollution control. Sewage sludge can be disposed safely only by: • Utilizing it in some way, in particular by returning it to the natural cycle, or • Withdrawing it from the cycle by means of dumping, i.e., controlled tipping. However, owing to its harmful properties and their potentially undesirable and deleterious effects, sewage sludge cannot be disposed of in the raw state. It must first undergo some suitable form of pretreatment, the aim being to render it fit for disposal, i.e., to alter and improve its characteristics through various processes os that the ultimate means of disposal selected has no detrimental effects on the environment. Given this objective, the type of treatment and its extent and result are geared to the requirements of the disposal method. The properties and composition of raw sewage sludge can have undesirable and harmful effects. These characteristics include: • a high proportion of digestible organic matter; • a high water content; • the presence of a critically high load of pollutants; • the presence of pathogens. 2.1.2. Basic steps of treatment The process of altering and improving the properties and composition of sewage sludge comprises the following basic steps: Stabilization; Separation of the sludge liquor, i.e., dewatering; • Disinfection of the sludge; Incineration of the sludge. Stabilization is a crucial step, both where the treated sludge is to be spread on farmland or where tipping is the method of disposal chosen. As a rule, tipping should not take place until the liquid content of the sludge has been reduced to a satisfactory level. Future reglementations for tipping may although lead to input criteria for organic matter so that sludge has to be incinerated in advance. Where the sludge is to be used in agriculture, forestry or horticulture, disinfection is often essential and the concentration of potentially toxic substances must in any case be suitably low. These basic steps must form part of any sludge treatment and disposal system. The choice of steps and their chronological order are variable according to the final utilization and disposal goal. The organic elements of the raw sludge resulting from treatment processes are not stabilized. The primary objective of the stabilization process is to stabilize the substrate, with a substantial reduction in any constituents liable to produce odour. Secondary objectives include: • A reduction in the volume of sludge (solids); • Enhancement of the dewaterability of the sludge; • Reduction of pathogens; • Production of biogas (only under anaerobic conditions), and creation of storage capacity. The objectives of the process, and thus the degree of stabilization, should be geared

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to the destination of the sludge, be it further treatment, utilization or disposal. The key objectives of the stabilization process are thus: • Application to agricultural land (in liquid form); • Application to agricultural land (in dewatered state); • Storage of liquid sludge in sludge lagoons; • Tipping in dewatered state; • Tipping of residues after incineration. Sludge can thus be stabilized by means of biological (aerobic or anaerobic), physical a n d / o r chemical and, in particular, thermal decomposition and transformation processes. With increasing concentration of the solid matter, or reduction in the water content by separation of the sludge liquor, i.e., dewatering, not only the volume of the sludge but also its properties are altered. From the point of view of volume, concentration of the solids beyond 30%, i.e., reducing the water content to under 70%, is of little practical use, but when it comes to further treatment and disposal of the sludge it could be important to withdraw enough liquor to eliminate the sticky properties of the sludge in particular and to improve the sludge handling. The extent of the water-binding capacity of the sludge is a function of the constituents. The organic constituents of sludge bind very readily to water, but the colloidal and gel-like constituents present in secondary sludges from activated sludge plants and hydroxide sludges in particular bind more readily still, thus contribution substantially to the considerable waterbinding capacity of such sludges. This also explains why different types of sludges with quite different composition and binding capacity are produced by the processes used at each individual wastewater treatment stage to eliminate the various constituents. The solid matter content of sewage is not really a good measure for determining its suitability for tipping. There will be further figures in the future, such as ground-mechanical figures and input criteria for the organic matter content. Those figures will lead to further treatment necessities before sludge tipping. Processes and steps involved in the separation of the sludge liquor are: • Conditioning, the appropriate dosing depends on the type and amount of the conditioning agent. • Thickening and dewatering, the specific initial solids content and the specific process result - the latter chiefly involving the throughput attainable, the separation effect achieved and the final solids content are decisive variables. • Drying, as a separate stage or in combination with incineration; the initial solids content of the feed is a decisive variable. In addition, the capacity of sludge to bind water - expressed, for example, in terms of its thickening capacity and dewaterability - can even be reduced as a result of stabilization. This is one of the undesirable side effects typical of 'cold' aerobic stabilization. Moreover, sludge which has already been partially digested does not lend itself at all well to conditioning or dewatering. As a consequence of these associations, it is more necessary than ever before, taking into account the specific dependencies, to come up with the best possible combination of wastewater treatment and sludge treatment.

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The purpose of disinfection is to render the sludge safe from a health point of view, whether or not the sludge liquor has been separated, and independent of the basic step of stabilization. Prior disinfection is essential if sewage sludge is to be used in agriculture where: • The sludge is to be spread on arable land, in the growing season. • The sludge is applied to grassland and fodder crops. For sludge disposal by tipping after dewatering or after incineration sludge has not to be disinfected at all. Established and proved disinfection techniques include those involving an external source of heat: • Pasteurization; • Thermal conditioning; • Thermal drying. Those involving spontaneous heating: Aerobic-thermophilic sludge stabilization; Bio-reactor-composting; • Composting jointly with refuse; Addition of lime. Irradiation techniques such as: Gamma irradiation. And, adjustment of the pH value: Addition of hydrated lime, e.g., during conditioning; Addition of quicklime. 2.1.3. Outlook on future demands

Objectives in sewage sludge management are changing in the near future because of new regulations and the increasing public awareness concerning any waste disposal solutions. It is, therefore, to be expected that treatment and the techniques employed will have to comply with much more stringent requirements, in particular as regards quality of the sludge and reliability of the techniques used. Treatment processes in general will have to be more sophisticated. This will result in the application of structured processes tailored very much to the requirements of the particular method of safe disposal selected, and treatment processes will have to be optimized both technically and economically. Sewage sludge incineration will become an increased application. Applications may be: • Incineration of sewage sludge in lignite firing power plants. • Incineration of sewage sludge in coal melting chamber firing power plants. • Incineration of sewage sludge in waste firing. • Separated incineration of sewage sludge (fluidized bed). • Incineration of sewage sludge in cement and kiln or other industrial firing. If sewage sludge incineration in power plants and industrial incineration plants will become a wide application sludge has to be dried in advance in most of the cases which would lead to an increasing market for sludge drying systems. Those conclusions result in the application of structured process orientated very much to the requirements of the particular goal of safe disposal selected on a regional basis.

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3. Sewage sludge management 3.1.1. Current situation The current situation in the field of waste management is determined by the following factors: • Increasing amounts of waste to be treated. • Increasing requirements for disposal, e.g., pretreatment. • Shortage of treatment capacities. • Growing public criticism due to increasing concentrations of hazardous substances in the environment-the argumentative word being 'dioxins'. However, in the field of municipal and hazardous waste management avoiding and reduction concepts might help to solve or mitigate the problems, this is unfeasible for sewage sludge. On the contrary, most measures to improve wastewater treatment result in larger amounts of sewage sludge to be treated. Utilization and dumping are the remaining disposal possibilities. Utilization in sludge management means either utilizing the material itself in agriculture or utilizing its energy potential in thermal processes. At present, in most countries where wastewater treatment is developed to a high standard the amount of sludge used in agriculture is decreasing because of restrictions and a lack in acceptance from the farmers (in Germany 20% is used in agriculture). Currently, dumping is the most important disposal path. This practice is limited due to a lack of dumping-space, problems in handling, and increasing costs. In Germany, additionally to this, federal authorities have developed technical guidelines, by which future dumping requirements are defined. Restrictions on the base of input criteria are given. Dumping of organic matter is restricted and mineralization and in some cases immobilization of the inorganic substances is demanded. This requires a drastically increased need for incineration capacities. The above-described situation shows the necessity of a new orientation in sewage sludge management. Whereas in the past local organization and realization has been sufficient, increased requirements for future sludge management will demand for regional management concepts. The latter includes agricultural sludge utilization, sludge incineration optional with previous sludge drying, disposal of the residual fraction on landfill sites, and logistical integration of all elements and processes. 3.1.2. Methodology In order to design a regional sewage sludge management concept first of all the region and the sewage treatment works have to be defined. Hereby it is recommended to adjust the concept region to already existing administrative structures. This makes it easier to integrate sludge management in the whole complex of waste management. Second, all relevant information related to sewage sludge need to be compiled in a data base. Including data for every wastewater treatment plant concerning the quantity of sewage sludge, specific sludge characteristics, as well as present existence and capacity of sludge treatment processes. Special interest has to be given to future development of this data. Therefore, all relevant planning activities must be taken into account. In particular, an increase in sludge quantities, due to phosphate elimination or rainwater treatment, must be considered in future oriented concepts.

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Third, potential targets for sludge disposal of the concept region are to be selected and their specific requirements are to be defined. Fourth, target-oriented process chains, connecting the concept regions treatment plants to the disposal targets need to be developed. It is recommended to prefer flexible concepts, which provide interfaces to different disposal targets rather than one-dimensional solutions. Working-out a sludge management concept for a region, it is necessary to determine detailed process variants/options based on the process chains designed above. These options must be adjusted to both, the specific requirements of the specific regions'wastewater treatment plants as found out in the second working step and to the requirements of relevant disposal facilities as defined in the third step. Location-finding for treatment centers and defining catchment areas are parts of the concrete concept determination. Processes and capacities for sludge treatment must be adapted for every wastewater treatment plant locally and for sludge treatment centers regionally. The principal operational options for disposal in practice may be broadly classified into: Sludge treatment, if any, at an originating works and agricultural use; the use may be local for small works or over fairly substantial areas for large works. • Sludge treatment at a central works and agricultural use. Sludge treatment, if any, at a central works and marine dispersal (some nearby inland works may send sludge for co-dispersal), not allowed in Europe any more. • Sludge treatment, if any, at a central works and disposal to landfill or sacrificial land. The final proceeding of management concept compilation is to check the concept options by considering cost-effectiveness in order to find the optimum solution. This can be realized by evaluating the specific costs of the process steps: dewatering, transportation, drying, and incineration. The costs of a management concept option can be obtained for each wastewater treatment plant by combining these costs according to the process steps of the option. The overall costs of all regarded treatment works result in the total costs of the management concept variant. This allows the monetary comparison among the different options and, thus, the determination of the most cost effective one.

4. Privatization as organization form for wastewater utility management

4.1.1. Contribution of private companies The privatization of the public water companies would make it possible for the public utilities in developing countries to benefit from the know-how of large intemational companies specialized in public services management. The immediate consequences could be: • Reduction of operating expenses: personnel, equipment, products, premises. • Improvement of the efficiency of installations. • Decrease of the deterioration of equipment, by regular maintenance and replacement of faulty parts. • Reduction of outstanding payments through rigorous attention to client portfolios and monitoring customer files.

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Three kinds of measures could favor the privatization of public utilities: • Organization of the public utilities in two separate companies, one for the assets, a second one for the daily operation. • Participation of the international institutions as shareholders in the capital of the operating company. Incitement of local authorities to privatization through conditional project funding; the international institutions tie up their financing to the condition that the user sign a contract with an experienced private group for an extended period. In the most common scheme, the public utility company keeps the global responsibility of the public service, but delegates to a private company the daily operation concerning production, operation, maintenance and customer management. This organization shows many advantages: • Local Government keeps through the public utility company, its prerogatives conceming the development and control of the public service. • The public utility company remains the owner of the equipment and assumes the strategic choices concerning the selection and funding of new equipment. • The public utility company delegates daily management to a specialized company, but continuous to ensure its control, according to the rules fixed in the contract. • The financial implication of the specialized company in the capital of the operating company is a guarantee for good management. • The payment of the operating company is directly related to the amount of its cashing, so its efforts will benefit the public utility company which will receive payment for its investments. • The set up of an autonomous operating company allows for a clarification of the relationship between the public service operator and its main customer - the State. • The presence of a specialized partner offers opportunities for a wide opening towards: new technical information, new products, personnel training. 4.1.2. The risk factor: main limitation to the extension of privatization The risk factor constitutes the main obstacle to privatization. Any investor must be prepared to take risks, and even more so if he invests in developing countries, however, the risk is much larger in public utilities than in any other activity for two main reasons. Firstly, since the utilities have great social impact, the political authorities in some countries may be tempted to take authoritarian and arbitrary action. Secondly, investments in the utility field are programmed for much longer periods of amortisation than in other activities, say industry or real estate. Time is a major factor in increasing risk. 4.1.3. Direct management by local authorities • Direct administration • Autonomous administration For technical reasons, and often for political reasons, a balanced budget is often difficult to attain. 4.1.4. Delegated management-different types of privatization Types of contracts binding the public authorities and the private operators: • Concession

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• • • •

Leasing Administration with financial interest Management Service Risk is very high in the 'concession' type (or build, operate, transfer, BOT) and very low in the service type. In the lease type, the operator finances the operating capital, but does not finance new works. In the administration type, the operator does not finance the capital, and gets a bonus according to productivity rules. Those two contracts are believed to be the most appropriate ones for privatization in developing countries (see table in Appendix). Operational/leasing contract: Infrastructure financed and owned by municipality. Operation and maintenance contracted to private operator. Operator provides management, working capital. Frequently operator also finances specific categories of repair and maintenance. Operator bills customers. Duration is normally 10 to 15 years. Existing staff normally offered employment with operator. Concession Contract (Build Operate Transfer): • Private operator finances the creation of infrastructure. • Private operator provides working capital. • Private operator designs, constructs and commissions the new infrastructure. • Private operator operates and maintains the system.

4.1.5. Tariffs • Operator bills and collects revenue from customers. • Tariff per m 3 covers operating costs, interest and amortisation of capital. • Tariff is formula based on official indices. 4.1.6. Control and duration Build, operate, transfer B.O.T. • Municipality controls quality of service provided. • At the end of the contract period all property and infrastructure reverts to the municipality. • Length of contract period normally 20-25 years. • Existing staff normally offered employment with operator. 4.1.7. Regulation • Regulation under the contract. • Regulation under state law. • Self-regulation by operator. 4.1.8. Flexibility • Great advantage of the approach. • Both 'Lease' and 'Concession' contracts can be easily adapted to specific local conditions.

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A hybrid of Lease and Concession is becoming increasingly common. A group of municipalities can create a syndicate which contracts out its services to a single private operator. Ownership remains with public sector. Contract provides: Clear objectives, clear standards, strong control, regulated price. Control firmly in hands of public sector. Operational responsibilities delegated to private sector. 5. Industrial effluent standards

5.1.1. Waste quality standards for receiving water (ambient standards) With regard to the promulgated ambient water quality/criteria standards ( W Q / C S ) for receiving waters, generally these represent 'reworking' of the industrialized countries/criteria standards (IC/CS) done essentially by academicians, with little reference to their suitability and appropriateness for the real-world developing countries (DC) conditions. Where the natural waterways have been little affected by development, and in rivers above urbanizing/industrializing zones, the CS adapted from the ICs may be appropriate in representing natural conditions not requiring investment action programs to meet the CS, for example, for major ions and other mineral characteristics, including iron and manganese, physical parameters such as DO and color, and heavy metals and other toxics. Where the natural WQ characteristics have been seriously degraded by development pollution, then the W Q / C S adapted from the ICs are generally inappropriate and not meaningful because to meet the I C / C S will require levels of WPC investment much beyond those foreseeable in the decades ahead. Unfortunately, there has been a tendency for DC/NEnPAs to believe that promulgation of such W Q / C S will somehow cause the country establishment to meet them, without the use of economic analyses to show how the CS and be expected to be attained. In this sense the promulgation of the W Q / C S is believed to be counter-productive and confusing and leads to loss of creditability of the National Environmental Protection Agency (NEnPA) or other agencies which promulgate the standards. A much more realistic approach for setting ambients is to develop a firm data base on the existing and projected WQ characteristics for the water body of concern, then using the I C / C S as guides, to prepare CS for the particular water body which can be expected to be met and which represents an appropriate economic-cure-environmental balance. This is the approach being used by Hong Kong. This is also the approach which has been utilized in part by Thailand in setting transparency standards for the Phuket international beach resort at Karon Bay. The D C / W Q / C S for water bodies have generally been set for a number of classes or categories depending upon beneficial water use (BWUs), with each class category usually representing several BWUs. Because of the variation in the needed CS from one BWU to another, it would be advantageous to set the CS for each BWU, and moreover, by subdivisions of BWUs, for example, CS for international resort recreational waters vs. other recreational uses, for sensitive vs. nonsensitive fish species, for various levels of water treatment to be provided for different types of raw water supply, etc.

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Table 3 Industrial effluents standards Thailand [2] Items

Units Standards

BOD (5 day at 20°C) m g / l

Suspended solids

mg/l

Dissolved solids

mg/!

pH Permaganate Value Sulfide as H2S Cyanide as HCN Tar Oil and grease Formaldehyde Phenol and cresols Free chlorine Insecticides Radioactivity Heavy metals Zinc (Zn) Chromium (Cr) Arsenic (As) Copper (Cu) Mercury (Hg) Cadmium (Cd) Barium (Ba) Selenium (Se) Lead (Pb) Nickel (Ni) Manganese (Mn) Silver (Ag)

In summary,

Remarks

Fishery canning max. 100 Starch Ind. Centrifugal max. 60 Sedimentation max. 100 Noodle Ind. max. 100 Tanning Ind. max, 100 Pulp Ind. max. 100 Frozen Food Ind. max. 100 ratio 1 / 8 to 1/150 max. 30; 1/151 to depend on dilution ratios of wastewater and receiving water 1/300 max. 60; 1/301 to 1/500 max. 150 max. 2000 or under office's not higher than receiving water consideration but not more than 5000 dissolved solids 5000 m g / I if salinity of receiving water is higher than 2000 mg/I 20-60

mg/I b/I

5-9 max. max. max. none max. max. max. max. none none

mg/l -

max. 5.0 max. 0.5 max. 0.25 max. 1.0 max. 0.005 max. 0.03 max. 1.0 max. 0.02 max. 0.2 max. 0.2 max. 5.0 -

60 1.0 0.2 Refinery and Lubricant Oil Idustry 5.0 1.0 1.0 1.0

Zinc Zinc Zinc Zinc

Industry Max. Industry Max. Industry Max. Industry Max.

3.0 3.0 0.002 0.01

Zinc Industry max. 0.2 Zinc Industry max. 0.02

t h e m o s t a p p r o p r i a t e a p p r o a c h s e e m s to b e in u s i n g t h e p u b l i s h e d I C

d a t a o n l y a s a g u i d e , a n d to p r e p a r e C S b a s e d o n h a r d d a t a o n t h e a c t u a l / p r o j e c t e d conditions

for the water

body

of concern,

separately

for each

important

BWU,

WQ to

achieve an economic-cum-environmental balance for the present and foreseeable future c o n d i t i o n s . W a t e r q u a l i t y s t a n d a r d s f o r c o u n t r i e s in S o u t h e s t A s i a a r e s u m m a r i z e d in T a b l e s 1 a n d 2.

132

U. Stoll / Resources, Conservation and Recycling 16 (1996) 113-133

Table 4 National environmental quality control standards for municipal and liquid industrial effluents (values in m g / i unless specified [3]) S. No.

Parameter

Standards

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32

temperature *C pH 5-days BOD at 20°C COD total suspended solids total dissolved solids grease and oil phenolic compounds chloride (as CI) fluoride (as F) cyanide (as CN) detergents (as MBAS) sulphate (SO 4) sulphide (S) ammonia (NH 3) pesticide, herbicide, fungicide, insecticide cadmium chromium (tfivalent and hexavalent) copper lead mercury selenium nickel silver total toxic metals zinc arsenic barium iron manganese boron chlorine

40 6.0-10.0 80 150 150 3500 10 0.1 1000 20.0 2.0 20.0 600 1.0 40.0 0.15 0. I 1.0 1.0 0.5 0.01 0.5 1.0 1.0 2.0 5.0 1.0 1.5 2.0 1.5 6.0 1.0

5.1.2. Wastewater effluents For waste effluent standards, the tendency in most DCs has been more realistic, because of the relative ease of checking the effluent CS against actual condition; hence, the CS generally incorporate flexibility to enable situations to be handled on a case-by-case basis. Generally, however, it is not yet recognized that waste effluent CS have little usefulness unless accompanied by a minimum competent WQ monitoring program, and limited progress has been made in such monitoring because of the very considerable cost as well as the complexity of the technology involved including capability for economic analysis of monitoring costs to justify their need. Industrial effluent standards for Thailand and Pakistan are given in Tables 3 and 4.

U. Stoll / Resources, Conservation and Recycling 16 (1996) 113-133

133

5.1.3. Monitoring As noted above, a continuing minimum competent monitoring program is essential if W Q / C S are to be meaningful, whether for ambient WQ, community water supply or waste effluents. Some progress being made but many D C / W Q monitoring projects have emphasized mass data collection only with little attention to such basic questions as how to plan a meaningful/efficient monitoring program, how to use the collected data effectively to influence planning of continuing development investment, and how to prove to decision makers that the benefits of the monitoring justify continuing investment in monitoring. 5.1.4. Tentative nature of standards All W Q / C S should be considered as tentative, suiting the present DC conditions, subject to change as development proceeds, as has actually been the case in the ICs. 5.1.5. Marine receiving waters The W Q / C S should differentiate between marine waters compared to fresh waters, and, for marine waters, between confined marine waters such as bays and estuaries where seawater dilution may be quite limited, and open ocean waters with unlimited dilution. 5.1.6. USEPA / Water Quality Criteria manual USEPA's 'Quality Criteria for Water, 1986', is a valuable reference with updated basic information relating to W Q / C S , useful for ICs and DCs. For example, the 1986 report notes that limits on phenols for community water supply have tended to be much more restrictive than justified. It is suggested that all DCs review their W Q / C S with reference to the updated USEPA information [1].

References [1] Environmental System Reviews, 1993. Appropriate Environmental Standards for Developing Countries. ENSIC, No. 35, Asian Institute of Technology, Bangkok, Thailand. [2] PCD - Pollution Control Department, 1994. Laws and Standards on Pollution Control in Thailand. 3rd edn. [3] PEPA - Pakistan Environmental Protection Agency, 1993. The Gazette of Pakistan, Statutory Notification No. SRO. 742(1)/93, lslamadad.