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Water SA

versión On-line ISSN 1816-7950
versión impresa ISSN 0378-4738

Water SA vol.42 no.2 Pretoria abr. 2016

http://dx.doi.org/10.4314/wsa.v42i2.18 

TECHNICAL NOTE

 

The formulation of synthetic domestic wastewater sludge medium to study anaerobic biological treatment of acid mine drainage in the laboratory

 

 

M Francis van den Berg*; Marelize Botes; T Eugene Cloete

Department of Microbiology, Stellenbosch University, 7600, Stellenbosch, South Africa

 

 


ABSTRACT

Requirements for successful biological treatment of acid mine drainage (AMD) rely on the reduction of sulphates by microorganisms using a suitable organic carbon source. Various carbon sources, such as domestic wastewater sludge, have previously been used in the semi-passive biological treatment of AMD. Domestic wastewater sludge is however highly variable in its composition, making laboratory experimentation difficult. Synthetic medium was therefore formulated based on the chemical oxygen demand (COD) and the biological degradable organic matter (BOD) of domestic wastewater sludge. Four synthetic media compositions were formulated consisting of different ratios of meat extract, vegetable extract, sodium chloride, potassium phosphate, urea, ammonium chloride, iron sulphate, magnesium sulphate and glucose. The media composition with BOD and COD measurements closest to that of anaerobic domestic wastewater sludge was selected for further studies. The combination of AMD to synthetic wastewater sludge in 3 ratios was determined for COD and sulphate reduction in bioreactors over a period of 90 d. The highest reduction of 86.76% in COD and 99.22% in sulphate content were obtained in a 1:1 AMD: synthetic domestic wastewater sludge (SDWWS) ratio that calculated to a COD/sulphate ratio of 3.

Keywords: acid mine drainage, synthetic domestic wastewater sludge, sulphates, COD


 

 

INTRODUCTION

Industrial and mine wastewater is acidic in nature that contains sulphur, pyrite and other heavy metals and is generally referred to as acid mine drainage (AMD) (Geremias et al., 2003). AMD is formed during biological and chemical oxidation of the sulphur-containing compounds in the effluent to sulphate, when exposed to dissolved oxygen, water and micro-organisms (Nordstrom and Alpers, 1999; Benner et al., 2000; Baker and Banfield, 2003; Johnson and Hallberg, 2003). AMD is regarded as an environmental pollutant that may negatively impact environmental (Peplow and Edmonds, 2005; Lee et al., 2010) and human health (Keller et al., 2005).

The maximum sulphate level allowed in industrial effluent, in South Africa, is 600 mg/L (DWAF, 1996). However, AMD may contain sulphate concentrations as high as 30 000 mg/L (Poinapen et al., 2009). Treatment of AMD to reduce the sulphate concentrations and neutralise the pH before release into the environment is essential. AMD can be treated in anaerobic bioreactors that rely on sulphate-reducing bacteria (SRB) (Garcia et al., 2001; Kappler and Dahl, 2001; Burns et al., 2012; Sânchez-Andrea et al., 2012). SRB use inorganic sulphate as a terminal electron acceptor obtained by oxidation of carbon sources and the reduction of sulphate or molecular hydrogen to hydrogen sulphide (LeGall and Fauque, 1988; Garcia et al.,2001).

A prerequisite for AMD treatment using bacteria relies on a suitable organic substrate, a sulphate-reducing bacterial consortium and anaerobic conditions, where the sulphate in the system is reduced and the alkalinity increased to neutralise the AMD. A parameter used in biological sulphate reduction is the COD to sulphate ratio. A ratio of 0.67 indicates sufficient sulphate available for complete reduction of organic material (Vela et al., 2002). Therefore the challenge is to find a suitable inexpensive and sustainable carbon source for adequate reduction of sulphates (Santamaria et al., 2014). The co-treatment of AMD and municipal wastewater has become a treatment option of interest as the simultaneous treatment of municipal wastewater and AMD allows a reduction in treatment costs (Strosnider et al., 2011a; Strosnider et al., 2011b; Strosnider et al., 2013). A 1:1 ratio of AMD and sewage also showed a significant decrease in acidity, organic matter, nutrients, iron and manganese concentrations, and complete removal of pathogens (Neto et al., 2010). The chemical composition of domestic waste varies (Al-Salem, 1987; Mohammed et al., 2012) and representative synthetic domestic sludge does not exist (Hiraishi et al., 1998; Mazumder, 2010). The aim of this study was to formulate a synthetic domestic wastewater sludge to study anaerobic biological treatment of AMD in laboratory studies. The efficiency of the synthetic formula was evaluated by determining sulphate and COD reduction.

 

MATERIALS AND METHODS

Formulation of synthetic domestic wastewater sludge media

For the formulation of the synthetic anaerobic domestic wastewater sludge (SDWWS), only the nutritional value of the anaerobic domestic wastewater sludge was of interest and not the specific chemical composition itself, hence the exclusion of most trace metals (Stover et al., 1976; Alloway and Jackson, 1991). The chemical oxygen demand (COD), biological oxygen demand (BOD), sulphate concentration and pH determined for anaerobic domestic wastewater sludge were used as the nutrient parameters, as described below.

Chemical analyses of anaerobic domestic wastewater sludge

Anaerobic domestic wastewater sludge was obtained from the anaerobic digester tank at the Pniel wastewater treatment plant situated on the outskirts of Stellenbosch by collecting samples in 5 L plastic containers. These containers were kept at room temperature (22°C) until chemical analyses were conducted within 24 h. The COD and sulphate concentrations were determined by using the Merck Spectroquant Pharo 300 and cell test kits according to the recommended protocol. A BOD 16S kit from Oxitop was used to determine the BOD and pH was determined by using a digital pH meter (PCTestr 35 Multi-Parameter).

Composition of the synthetic domestic wastewater sludge media

Vegetable extract (Sigma-Aldrich (Pty) Ltd., Johannesburg, South Africa) and meat extract (Sigma-Aldrich) served as the basis of the synthetic media as it incorporates the protein, carbohydrate and fat content. The rest of the components included sodium chloride (Sigma-Aldrich), potassium phosphate (Sigma-Aldrich), urea (Sigma-Aldrich), ammonium chloride (Sigma-Aldrich), iron sulphate (Sigma-Aldrich), magnesium sulphate (Sigma-Aldrich) and glucose (Sigma-Aldrich) (Table 1). Four different ratios of the mentioned components were prepared and chemical analyses including COD, BOD, sulphate concentrations and pH were performed as described earlier. The medium that compared best to the chemical analysis of SDWWS was selected for further optimisation. The optimised SDWWS media were then used for further studies.

 

 

Determining the optimal acid mine drainage to synthetic anaerobic domestic wastewater sludge ratio

Experimental design for the anaerobic treatment of AMD

Sterile medical drip bags (1 L) (Stelmed, Stellenbosch, South Africa) served as small anaerobic bioreactors. Acid mine drainage sampled from an Exxaro coal mine was couriered overnight in 5 L plastic containers and stored at room temperature (20-21°C) until use. Three ratios of AMD and the selected SDWWS (as described earlier) were prepared to a final volume of 900 mL in the bioreactors and the pH adjusted to 7.5 with 5 mM NaOH solution where needed (Table 2). The bioreactors were then incubated upright in a dimly-lit enclosed environment at room temperature (20-21°C) for 90 d. Incubation periods in the co-treatment of AMD and domestic wastewater or sludge vary between 40 days and 300 days depending on the experimental set-up (Pulles and Heath, 2009; Strosnider et al., 2011c; Hughes and Gray, 2013) (Fig. 1). Mixtures of AMD and sterile distilled water in the ratios of 1:1, 1:2 and 2:1 served as experimental controls. Two trials were run in triplicate.

 

 

 

 

From here on the 1:2 ratio will be referred to as Ratio 1, the 1:1 ratio referred to as Ratio 2 and the 2:1 as Ratio 3.

Microbial inoculum used in the bioreactors

Anaerobic domestic wastewater sludge obtained from the anaerobic digester tank at the Pniel wastewater treatment plant was used as microbial inoculum. Samples were collected in 5 L containers and left overnight at 21°C. Thereafter the bioreactors containing the SDWWS:AMD ratios (Table 2) were inoculated with 10 mL domestic wastewater sludge.

Chemical analyses of the different ratios of synthetic anaerobic domestic wastewater sludge to acid mine drainage

The COD and sulphate concentrations of the different ratios of SDWWS to AMD were determined on Days 1 and 90 of the trials as described earlier.

 

RESULTS AND DISCUSSION

Formulation of synthetic anaerobic domestic wastewater sludge

The chemical analyses of the four SDWWS media are indicated in Table 3. The COD and BOD of Medium 3 were 2 600 mg/L and 330 mg/L, respectively, and compared best to the COD (3 650 mg/L) and BOD (320 mg/L) of anaerobic domestic wastewater sludge. The concentrations of components in Medium 3 were further optimised by increasing the concentration of meat extract and decreasing the concentrations of vegetable extract, sodium chloride, magnesium sulphate, potassium phosphate, iron sulphate, urea and glucose (Table 4). The COD of the optimised synthetic SDWWS medium was 3 646 mg/L, the BOD was 317 mg/L and the pH 6.9. The synthetic anaerobic domestic wastewater sludge was therefore standardised and thereby excluded the potential variability that could be found when anaerobic domestic wastewater sludge samples are collected at wastewater plants (Snaidr et al., 1997; Boon et al., 2002; Juretschko et al., 2002; Henze, 2008; Abbas et al., 2011).

 

 

 

 

Chemical analyses of the different ratios of synthetic anaerobic domestic wastewater sludge to acid mine drainage

The COD/sulphate ratios of the three different AMD:SDWWS ratio mixtures (1:2; 1:1; 2:1) were calculated as 1.5, 3 and 4. The COD of all of the controls decreased between 0.83% and 3.06% (Figs 2 and 3). The media control values are not indicated in the graphs. A decrease of between 0% and 6.25% in sulphate content in the controls can possibly be attributed to the bacterial oxidation of iron, forming an oxyhydroxysulfate of iron with sulphate as structural component (Bigham et al., 1990). The highest reduction in COD (86.76%) and sulphate content (99.22%) was obtained in Ratio 2, although reductions in both COD and sulphate levels in Ratio 1 and Ratio 3 were similar (Figs 2 and 3). Therefore it can be concluded that COD/sulphate ratios of 1.5 to 4 in biological treatment of AMD with wastewater sludge are adequate for sulphate reduction. These results were confirmed by Deng and Lin (2013) who treated AMD and municipal waste (MW) in different ratios in a two-stage process by first mixing the two wastes followed by anaerobic biological treatment. More than 80% COD and sulphate was removed at COD/sulphate ratios of 0.6 to 5.4. Poinapen and co-workers (2009) investigated the use of upflow anaerobic sludge bed reactors with sewage as carbon source. The trial was conducted at 35°C and resulted in a sulphate reduction of > 83% (from 1 500 mg/L to < 250 mg/L) with a 14 h retention time, compared to the reduction of > 99% (from 500 mg/L to < 7 mg/L) in this study (Figs 2 and 3).

 

 

 

 

CONCLUSION

A synthetic media was formulated to simulate the COD and BOD values of domestic wastewater sludge as a carbon source for the anaerobic treatment of AMD in batch reactors. The COD and sulphate content of the AMD were reduced by 86% and 99% by bioreactors containing a 1:1 AMD:SDWWS ratio or a COD/sulphate ratio of 3, and these results could be repeated in a second trial. The synthetic media will be used in future AMD studies to assess sulphate reduction under different parameters.

Small volumes of AMD and domestic wastewater sludge were treated per bioreactor in this study. The results obtained may differ in the treatment of larger volumes of wastewater. This should also be verified in future studies by up-scaling the process to determine the efficiency of the SDWWS and AMD combination in a bioreactor for COD and sulphate reduction.

 

ACKNOWLEDGEMENTS

The authors would like to thank Exxaro for funding.

 

REFERENCES

Abbas AH, IBRAHIM ABA, NOR MFM and ARIS MS (2011) Characterization of Malaysian domestic sewage sludge for conversion into fuels for energy recovery plants. Proc. National Postgraduate Conference (NPC), 19-20 September 2011, Kuala Lumpur.         [ Links ]

ALLOWAY BJ and JACKSON AP (1991) The behaviour of heavy metals in sewage sludge-amended soils. Sci. Total Environ. 100 151-176. http://dx.doi.org/10.1016/0048-9697(91)90377-Q        [ Links ]

AL-SALEM SS (1987) Evaluation of the Al Samra waste stabilization pond system and its suitability for unrestricted irrigation. Paper prepared for the Land and Water Development Division, FAO, Rome.         [ Links ]

BAKER BJ and BANFIELD JF (2003) Microbial communities in acid mine drainage. FEMS Microbiol. Ecol. 44 (2) 139-152. http://dx.doi.org/10.1016/S0168-6496(03)00028-X        [ Links ]

BENNER SG, GOULD WD and BLOWES DW (2000) Microbial populations associated with the generation and treatment of acid mine drainage. Chem. Geol. 169 435-448. http://dx.doi.org/10.1016/S0009-2541(00)00219-9        [ Links ]

BIGHAM JM, SCHWERTMANN U, CARLSON L and MURAD E (1990) A poorly crystallized oxyhydroxysulfate of iron formed by bacterial oxidation of Fe(I1) in acid mine waters. Geochim. Cosmochim. Acta 54 2743-2758. http://dx.doi.org/10.1016/0016-7037(90)90009-A        [ Links ]

BOON N, DE WINDT W, VERSTRAETE W and TOP EM (2002) Evaluation of nested PCR-DGGE (denaturing gradient gel electrophoresis) with group-specific 16S rRNA primers for the analysis of bacterial communities from different wastewater treatment plants. FEMS Microbiol. Ecol. 39 101-112. http://dx.doi.org/10.1016/s0168-6496(01)00198-2        [ Links ]

BURNS AS, PUGH CW, SEGID YT, BEHUM PT, LEFTICARIU L and BENDER KS (2012) Performance and microbial community dynamics of a sulfate-reducing bioreactor treating coal generated acid mine drainage. Biodegradation 2 (3) 415-429. http://dx.doi.org/10.1007/s10532-011-9520-y        [ Links ]

DENG D and LIN L-S (2013) Two-stage combined treatment of acid mine drainage and municipal wastewater. Water Sci. Technol. 67 (5) 1000-1007. http://dx.doi.org/10.2166/wst.2013.653        [ Links ]

DWAF (DEPARTMENT OF WATER AFFAIRS AND FORESTRY, SOUTH AFRICA) (1996) Water Quality Guidelines for South Africa: First Edition 1996. DWAF, Pretoria.         [ Links ]

GARCIA C, MORENO DA, BALLESTER A, BLAZQUEZ ML and GONZALEZ F (2001) Bioremediation of an industrial acid mine water by metal-tolerant sulphate-reducing bacteria. Miner. Eng. 14 (9) 997-1008. http://dx.doi.org/10.1016/S0892-6875(01)00107-8        [ Links ]

GEREMIAS R, PEDROSA RC, BENASSI JC, FAVERE VT, STOLBERG J, MENEZES CTB and LARANJEIRA MCM (2003) Remediation of coal mining wastewaters using chitosan microspheres. Environ. Technol. 24 (12) 1509-1515. http://dx.doi.org/10.1080/09593330309385696        [ Links ]

HENZE M (2008) Biological Wastewater Treatment: Principles, Modelling and Design. IWA Publishing, London.         [ Links ]

HIRAISHI A, UEDA Y and ISHIHARA J (1998) Quinone profiling of bacterial communities in natural and synthetic sewage activated sludge for enhanced phosphate removal. Appl. Environ. Microbiol. 64 (3) 992-998.         [ Links ]

HUGHES TA and GREY NF (2013) Co-treatment of acid mine drainage with municipal wastewater: performance evaluation. Environ. Sci. Pollut. Res. 20 7863-7877. http://dx.doi.org/10.1007/s11356-012-1303-4        [ Links ]

JOHNSON DB and HALLBERG KB (2003) The microbiology of acidic mine waters. Res. Microbiol. 154 (7) 466-473. http://dx.doi.org/10.1016/S0923-2508(03)00114-1        [ Links ]

JURETSCHKO S, LOY A, LEHNER A and WAGNER M (2002) The microbial community composition of a nitrifying-denitrifying activated sludge from an industrial sewage treatment plant analyzed by the full-cycle rRNA approach. Syst. Appl. Microbiol. 25 84-99. http://dx.doi.org/10.1078/0723-2020-00093        [ Links ]

KAPPLER U and DAHL C (2001) Enzymology and molecular biology of prokaryotic sulfite oxidation1. FEMS Microbiol. Lett. 203 (1) 1-9. http://dx.doi.org/10.1111/j.1574-6968.2001.tb10813.x        [ Links ]

KELLER J, OWENS CT, LAI JC and DEVAUD LL (2005) The effects of 17 beta-estradiol and ethanol on zinc- or manganese-induced toxicity in SK-N-SH cells. Neurochem. Int. 46 293-303. http://dx.doi.org/10.1016/j.neuint.2004.11.003        [ Links ]

LEE KY, KIM KW and KIM SO (2010) Geochemical and microbial effects on the mobilization of arsenic in mine tailing soils. Environ. Geochem. Health 32 31-44. http://dx.doi.org/10.1007/s10653-009-9263-4        [ Links ]

LEGALL J and FAUQUE G (1988) Dissimilatory reduction of sulphur compounds. In: Zehnder AJB Biology of Anaerobic Microorganisms. Wiley, New York.         [ Links ]

MAZUMDER D (2010) Simultaneous COD and ammonium nitrogen removal from a high-strength wastewater in a shaft-type aerobic hybrid bioreactor. Int. J. Environ. Sci. Dev. 1 (4) 327-332. http://dx.doi.org/10.7763/IJESD.2010.V1.64        [ Links ]

MOHAMMED RA, MOHAMMED AA and HASSAN IH (2012) Characteristics of raw domestic sewage for Basrah City. Basrah J. Eng. Sci. 12 (1) 60-71.         [ Links ]

NETO RR, CROCETTA MS, SOUZA MGR, ROCHA E, ZANUZ M and GOMES CJB (2010) Combined treatment of acid mine drainage and sewage in the State of Santa Catarina-Brazil. In: Wolkersdorfer C and Freund A (eds.) Mine Water and Innovative Thinking. Sydney, Nova Scotia.         [ Links ]

NORDSTROM DK and ALPERS CN (1999) Geochemistry of acid mine waters. The environmental geochemistry of mineral deposits. Part A: Process. Tech. Health Issues 6 133-160.         [ Links ]

PEPLOW D and EDMONDS R (2005) The effects of mine waste contamination at multiple levels of biological organization. Ecol. Eng. 24 101-119. http://dx.doi.org/10.1016/j.ecoleng.2004.12.011        [ Links ]

POINAPEN J, EKAMA GA and WENTZEL MC (2009) Biological sulphate reduction with primary sewage sludge in an upflow anaerobic sludge bed (UASB) reactor - Part 3: Bed settling characteristics. Water SA 35 (5) 543-552. http://dx.doi.org/10.4314/wsa.v35i5.49181        [ Links ]

PULLES W and HEATH R (2009) The evolution of passive mine water treatment - Technology for sulphate removal. In: Proceedings of the International Mine Water Conference, 19-23 October 2009, Pretoria, South Africa.         [ Links ]

SÁNCHEZ-ANDREA I, TRIANA D and SANZ JL (2012) Bioremediation of acid mine drainage coupled with domestic wastewater treatment. Water Sci. Technol. 66 (11) 2425-2431. http://dx.doi.org/10.2166/wst.2012.477        [ Links ]

SANTAMARIA B, STROSNIDER WH, QUISPE MRA and NAIM RW (2014) Evaluating locally available organic substrates for vertical flow passive treatment cells at Cerro Rico de Potosi', Bolivia. Environ. Earth Sci. 72 731-741. http://dx.doi.org/10.1007/s12665-013-2997-4        [ Links ]

SNAIDR J, AMANN R, HUBER I, LUDWIG W and SCHLEIFER K (1997) Phylogenetic analysis and in situ identification of bacteria in activated sludge. Appl. Environ. Microbiol. 63 (7) 2884-2896.         [ Links ]

STOVER RC, SOMMERS LE and SILVIERA DJ (1976) Evaluation of metals in wastewater sludge. J. Water Pollut. Control Fed. 48 (9) 2164-2175.         [ Links ]

STROSNIDER WH, WINFREY BK and NAIRN RW (2011a) Alkalinity generation in a novel multi-stage high-strength acid mine drainage and municipal wastewater passive co-treatment system. Mine Water Environ. 30 (1) 47-53. http://dx.doi.org/10.1007/s10230-010-0124-2        [ Links ]

STROSNIDER WH, WINFREY BK and NAIRN RW (2011b) Biochemical oxygen demand and nutrient processing in a novel multi-stage raw municipal wastewater and acid mine drainage passive co-treatment system. Water Res. 45 (3) 1079-1086. http://dx.doi.org/10.1016/j.watres.2010.10.026        [ Links ]

STROSNIDER WH, WINFREY BK and NAIRN RW (2011c) Novel passive co-treatment of acid mine drainage and municipal waste- water. J. Environ. Qual. 40 206-213. http://dx.doi.org/10.2134/jeq2010.0176        [ Links ]

STROSNIDER WH, WINFREY BK, PEERA RAM and Nairn RW (2013) Passive co-treatment of acid mine drainage and sewage: Anaerobic incubation reveals a regeneration technique and further treatment possibilities. Ecol. Eng. 61 268-273. http://dx.doi.org/10.1016/j.ecoleng.2013.09.037        [ Links ]

VELA FJ, ZAIAT M and FORESTI E (2002) Influence of the COD to sulphate ratio on the anaerobic organic matter degradation kinetics. Water SA 28 (2) 213-216. http://dx.doi.org/10.4314/wsa.v28i2.4887        [ Links ]

 

 

Received: 18 March 2015
Accepted in revised form 16 March 2016

 

 

* To whom all correspondence should be addressed. θ +27 21 808 2708; email: mbr@sun.ac.za

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