Microbial utilisation of natural organic wastes

Microbial utilisation of natural organic wastes

Available online at www.sciencedirect.com Acta Astronautica 54 (2004) 357 – 361 www.elsevier.com/locate/actaastro Microbial utilisation of natural o...

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Available online at www.sciencedirect.com

Acta Astronautica 54 (2004) 357 – 361 www.elsevier.com/locate/actaastro

Microbial utilisation of natural organic wastes V.K. Ilyina;∗ , I.A. Smirnova , P.E. Soldatova , I.N. Korniushenkovaa , A.S. Grininb , I.N. Lykovb , S.A. Safronovab a RF

State Scienti c Center Institute for Biomedical Problems, Ministry of Health, Khorasherskoye Shosse 76A, Moscow 123007, Russia b Moscow Baumann State Technical University, Kaluga, Russia Received 25 March 2002; received in revised form 14 November 2002; accepted 19 November 2002

Abstract The waste management strategy for the future should meet the bene4ts of humanity safety, respect principals of planet ecology, and compatibility with other habitability systems. For these purpose the waste management technologies, relevant to application of the biodegradation properties of bacteria are of great value. The biological treatment method is based upon the biodegradation of organic substances by various microorganisms. The advantage of the biodegradation waste management in general: • it allows to diminish the volume of organic wastes, • the biological hazard of the wastes is controlled and • this system may be compatible with the other systems. The objectives of our study were: • to evaluate e9ectiveness of microbial biodegradation of non-pretreated substrate, • to construct phneumoautomatic digester for organic wastes biodegradation and • to study microbial characteristics of active sludge samples used as inoculi in biodegradation experiment. The technology of vegetable wastes treatment was elaborated in IBMP and BMSTU. For this purpose the special unit was created where the degradation process is activated by enforced reinvention of portions of elaborated biogas into digester. This technology allows to save energy normally used for electromechanical agitation and to create optimal environment for anaerobic bacteria growth. The investigations were performed on waste simulator, which imitates physical and chemical content of food wastes calculated basing on the data on food wastes of moderate Russian city. The volume of created experimental sample of digester is 40 l. The basic system elements of device are digesters, gas receiver, remover of drops and valve monitoring and thermal control system. In our testing we used natural food wastes to measure basic parameters and time of biodegradation process. The diminution rate of organic gained 76% from initial mass taking part within 9 days of fermentation. The biogas production achieved 46 l per 1 kg of substrate. The microbial studies of biodegradation process

 Based

on paper IAF/IAA-01-G.4.01 presented at the 52nd International Astronautical Congress, 1–5 October 2001, Toulouse, France. author.

∗ Corresponding

c 2003 Elsevier Ltd. All rights reserved. 0094-5765/$ - see front matter  doi:10.1016/S0094-5765(03)00046-8

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revealed following peculiarities: (i) gradual quantitative increasing of Lactobacillus sp. (from 103 to 105 colony forming units (CFU) per ml), (ii) activation of Clostridia sp. (from 102 to 104 CFU/ml) and (iii) elimination of aerobic conventional pathogens (Enterobacteriaceae sp., Protea sp., staphylococci). The obtained results allow to evaluate e9ectiveness of proposed technology and to determine the leading role of lactobacilli and clostridia in process of natural wastes biodegradation. Our further investigations shall further be concentrated on creation of arti4cial inoculi for launching of food wastes biodegradation. These inoculi will include active and adapted strains of clostridia and lactobacilli. c 2003 Elsevier Ltd. All rights reserved. 

1. Introduction The increased duration of space Dights and a tendency to their most autonomisation state the necessity for implementation of a new and fast technology for human waste management in space. The waste management strategy for the future piloted space missions should meet the bene4ts of crewmembers safety, respect principals of planet ecology, and compatibility with biological LSS. For these purpose the waste management technologies, relevant to application of the biodegradation properties of bacteria may be of great value [1–4]. The biological treatment method is based upon the biodegradation of organic substances by various microorganisms. Decomposition during composting occurs with air (aerobically) or during biogas processing without air (anaerobically) and results in the reduction of any existing organic matter. The advantage of the biodegradation waste management in general: • it allows to diminish the volume of organic wastes, • the biological hazard of the wastes will be controlled, • this system may be compatible with the other biological ELSS (greenhouses), • the biogas created while biodegradation may be used for the other needs of space vehicle (propellants) and • the water obtained in the biodegradation processes may be used for the other needs of the space vehicle. The solid waste treatment strategies of the spaceDights are nowadays based on the principals of

isolation, compression and storage. This mainly concernfeces, vomit, plastic, soft paper and cellulose swabs. This technology was implemented on orbital stations. The objectives of the study were: • to evaluate e9ectiveness of microbial biodegradation of non-pretreated substrate, • to construct and to test pneumoautomatic digester for organic wastes biodegradation and • to study microbial characteristics of active sludge samples used as inoculi in biodegradation experiment. 2. Materials and methods As an inoculate we used active sludge of sewage water station, as a substrate we used disintegrated and water-suspended natural vegetable wastes and “waste simulator” i.e. vegetable substrate/which chemical content corresponds to that of origin natural food wastes. The fermentation was performed in anaerobic condition under the temperature 37◦ C in special digester. The e9ectiveness of biodegradation was evaluated on the results of gas productivity and mass of solid residual. 3. Results The technology of vegetable wastes was elaborated in IBMP. For this purpose the special unit was created where the degradation process is activated by enforced reinvention of portions of elaborated biogas into digester. This technology allows to safe

V.K. Ilyin et al. / Acta Astronautica 54 (2004) 357 – 361

359

Fig. 1. The scheme of the device for anaerobic biodegradation of plant food wastes.

energy normally used for electromechanical agitation and to create optimal environment for anaerobic bacteria growth. The investigations were performed on waste simulator, which imitates physical and chemical content of food wastes calculated basing on the data on food wastes of moderate Russian city. The volume of created experimental sample of digester is 40 l. The basic system elements are shown in Fig. 1. These are digester, gas receiver, remover of drops, and monitoring system. On the initial stages of our laboratory studies we used natural food wastes to measure basic parameters and time of biodegradation process.

The diminution rate of organic gained 76% from initial mass taking part within 9 days of fermentation. The biogas production achieved 46 l per 1 kg of substrate. Chromatography analysis revealed constant presence of carbon dioxide (83.36 –90.9%), air (2.7– 14.17%), and humidity (2%). The dynamics of methane content was 0.41– 0.47% (3 days) with further decrease to 0.1% (9 days). On the 9th day we also detected hydrogen (1.9%), which increased to 4.1% (13 days) and to 5.3% (21 days). The choromatograms of biogas chemical content are given in Fig. 2.

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Fig. 2. Biogas chemical content.

The microbial studies of biodegradation process revealed following peculiarities (Table 1): 1. gradual quantitative increasing of Lactobacillus sp. (from 103 to 105 colony forming units (CFU) per ml), 2. activation of Clostridia sp. (from 102 to 104 CFU/ml) and 3. elimination of aerobic conventional pathogens (Enterobacteriaceae sp., Protea sp., staphylococci).

Based on the obtained results the arti4cial inoculum was created which is capable to initiate biodegradation of vegetable wastes. This inoculum consists of active sludge adapted to wastes mixed with excretes of insects which consume plant wastes. The basic characteristics of inoculum microbial content is given in Fig. 3. Having adapted improved active sludge to the wastes we sampled and lyophilised this sludge at highest activity period (3rd day of biodegrada-

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Table 1 Microbial characteristics of vegetable wastes biodegradation

Table 2 The groups of microbes in content of arti4cial inoculum

N

Microbial groups

CFU/ml

1 2 3 4 5 6 7 8 9

Microbial group

Total aerobes Escherichia spp Enterobacteria Protea spp Streptococci Staphylococci Yeasts Lactobacilli Clostridia

Waste simulator Baseline

Ending

Termophylic anaerobes

103

7:6: × 106 7:2: × 106 4:0: × 104 1:0: × 102 — — — 2:8: × 106 2:9: × 103

2:0: × 106 6:0: × 106 — — — — — 2:8: × 106 5:2: × 103

Mesophylic anaerobes Mesophylic anaerobes including Clostridia Mesophylic anaerobes including Lactobacilli

106 105 106

Total Total Total Total Total Total

106 106 — — — —

aerobes aerobes aerobes aerobes aerobes aerobes

including including including including including

Escherichia Enterobacteria Protea Streptococci Staphylococci

Yeasts Actinomyces

— 105

Table 3 Advantages of proposed technology Technology

Days

Biodegradation of food wastes Biodegradation of food wastes using new digester Biodegradation of food wastes using improved active sludge Biodegradation of food wastes using liophylized arti4cial inoculum

14 –16 9 –10 5–6 3

Fig. 3. Quantitative content of improved active sludge microDora.

References

tion). The basic microbial characteristics of the obtained preparation (in dehydrated state) is given in Table 2. The obtained results allow to evaluate e9ectiveness of proposed technology and to determine the leading role of lactobacilli and clostridia in process of natural wastes biodegradation. In general, Table 3 illustrates the advantages of the proposed technology.

[1] A.M. Wachinski, Waste management: Project Mercury to the space station, Proceedings of the Conference on Engineering/ Construction/Operation, Albuquerque, 1988, pp. 1011–1020. [2] D.W. Rethke, C.R. Murphy, Flight test results of the DTO waste collector subsystem (WCS) for shuttle extended duration orbiter (EDO), NASA pub. 932295, 11pp. [3] L. Dall-Baumann, et al., Conceptual Designs for Lunar Base Life Support Systems, NASA pub.911325, 15pp. [4] N. Revis, G. Holdsworth, Importance of biological systems in industrial waste treatment, Potential application for the space station, NASA pub. 91-15943, 16pp.