Bioremediation of sago industry effluent and its impact on seed germination (green gram and maize)

In this study, we attempted two investigational systems: one is treatment of sago industry effluent by aerobic bacterial consortium and the other is impact of treated and untreated effluent on seed germination. For the treatment system, the starch degrading bacteria were isolated from sago industry effluent and effluent contaminated soil. The genera, Alcaligenes, Bacillus and Corynebacterium were found efficient in starch degradation. The selected isolates were tested for their efficiency on the degradation of starch both in Mineral Salts Medium (MSM) and in sago industry effluent. About 85% of the starch was degraded in MSM by a bacterial consortium composed of Alcaligenes, Bacillus and Corynebacterium, whereas in effluent the degradation of starch was only 63%. The physico-chemical properties such as electrical conductivity, total solids, suspended solids, dissolved solids, BOD, COD, nitrogen and phosphate were found decreased in effluent after 72 h. The pH of the effluent was relatively increased from 3 to 6.7. The study of seed germination (maize and green gram) was carried out at 25, 50, 75 and 100% concentrations of treated and untreated effluent using soil sowing method. Shoot length, root length, fresh weight, dry weight and chlorophyll content showed an increase when treated effluent was tested whereas a decrease of growth was noticed in untreated effluent tested seedlings. The results revealed that effluent treated by aerobic microorganisms has no negative impact on the seed germination and can be effectively used for irrigation.     

A bioprocess for the remediation of anaerobically digested molasses spentwash from biogas plant and simultaneous production of lactic acid

A bacterial isolate LAB-1 identified as Lactobacillus casei was cultivated in a fermentation medium containing biogas plant effluent. This effluent was generated after anaerobic digestion of molasses spentwash in biogas fermenters. In the bioremediation process of this very dark coloured effluent through the cultivation of L. casei, decrease in effluent's colour of 49 and 52% and reduction in COD level up to 54 and 57% were achieved using bacterial cells in free and immobilised system, respectively, in 5 days batch cultivation. During this process of bioremediation, a metabolite lactic acid was produced by this bacterial isolate with the yield of 10.9 and 11.3 mg/ml, in free and immobilised cells fermentation, respectively.     

A novel Acinetobacter sp. for treating highly acidic rubber latex centrifugation effluent

Summary A novel Acinetobacter sp. BTJR-10 isolated from highly acidic (pH 2.5–4.5) rubber latex centrifugation effluent with high COD (22000 mg/L) and BOD (5000 mg/L). This strain could effect 39.5% COD reduction on free cell inoculation of effluent without incorporation of additional nutrients after 8 days. Calcium alginate immobilized cells showed 16.4% and 25% COD reduction after 6 hrs. without aeration and after 1 hr. with mild aeration under batch process respectively. Whereas 44.0% COD reduction could be achieved after 6 hrs. on continuous treatment in a packed bed reactor with mild aeration. Further, even after 3 cycles 37% COD reduction was recorded with continuous treatment.     

Use of wood vinegar to enhance 5-aminolevulinic acid production by selected Rhodopseudomonas palustris in rubber sheet wastewater for agricultural use

This study aimed to produce inexpensive 5-aminolevulinic acid (ALA) in a non-sterile latex rubber sheet wastewater (RSW) by Rhodopseudomonas palustris TN114 and PP803 for the possibility to use in agricultural purposes by investigating the optimum conditions, and applying of wood vinegar (WV) as an economical source of levulinic acid to enhance ALA content. The Box–Behnken Design experiment was conducted under microaerobic-light conditions for 96 h with TN114, PP803 and their mixed culture (1:1) by varying initial pH, inoculum size (% v/v) and initial chemical oxygen demand (COD, mg/L). Results showed that the optimal condition (pH, % inoculum size, COD) of each set to produce extracellular ALA was found at 7.50, 6.00, 2000 for TN114; 7.50, 7.00, 3000 for PP803; and 7.50, 6.00, 4000 for a mixed culture; and each set achieved COD reduction as high as 63%, 71% and 75%, respectively. Addition of the optimal concentration of WV at mid log phase at 0.63% for TN114, and 1.25% for PP803 and the mixed culture significantly increased the ALA content by 3.7–4.2 times (128, 90 and 131 μM, respectively) compared to their controls. ALA production cost could be reduced approximately 31 times with WV on the basis of the amount of levulinic acid used. Effluent containing ALA for using in agriculture could be achieved by treating the RSW with the selected ALA producer R. palustris strains under the optimized condition with a little WV additive.     

Isolation and growth of the phototrophic bacterium Rhodopseudomonas palustris strain B1 in sago-starch-processing wastewater

An indigenous strain of the purple non-sulphur phototrophic bacterium, Rhodopseudomonas palustris strain B1, was selected for the utilization and treatment of wastewater from a sago-starch-processing decanter. Growth of Strain B1 under anaerobic–light conditions in the carbohydrate-rich effluent was optimized by using 50% (v/v) effluent diluted in a basal minimal mineral medium with the addition to 0.1% (w/v) yeast extract. The optimum level of nitrogen source supplement, ammonium sulphate, was 1.0g/l. Highest cell mass concentration was achieved by using tungsten lamps as the light source with a light intensity of 4 klux. Under these optimal conditions, a maximum biomass of about 2.5g dry cell/l with a pigment content of about 1.1mg carotenoid/g dry weight cell was achieved after 96h of anaerobic cultivation. There was a 77% reduc n the chemical oxygen demand (COD) of the effluent. A cell yield of about 0.59g dry weight cell/g COD was obtained.     

Cassava starch effluent treatment with concomitant SCP production

Yeasts and yeast-like organisms were chosen for the aerobic treatment of cassava starch factory effluent. A mixed culture of Candida utills and Endomycopsis fibuliger efficiently and rapidly utilized both starch and free sugars. After 28 h fermentation the protein content of the biomass was 22% (w/w), which remained unchanged during the remainder of the fermentation (60 h). This treatment removed 94% of the COD and 91% of the BOD.     

Decolorization of effluent from the bagasse-based pulp mills by white-rot fungus,Schizophyllum commune

Summary The effluent from bagasse-based pulp and paper mills can be decolorized with the white-rot fungus Schizophyllum commune. The influence of pH, nutrients and aeration on the decolorizing efficiency of this fungus has been determined. It was found that it could not degrade lignin unless a more easily metabolized carbon source was made available simultaneously. The addition of carbon and nitrogen not only improved the decolorizing efficiency of the fungus, but also resulted in reduction of the biological oxygen demand (BOD) and chemical oxygen demand (COD) of effluent. A 2-day incubation period was sufficient for lignin breakdown by S. commune. The efficiency of treatment of effluent with this fungus was highest at pH 4–5 and was further improved by intermittent aeration.     

COD and BOD reduction from coffee processing wastewater using Avacado peel carbon

The aim of this study was the assessment of reduction of chemical oxygen demand (COD) and biological oxygen demand (BOD) of wastewater from coffee processing plant using activated carbon made up of Avacado Peels. The complete study was done in batch mode to investigate the effect of operating parameters. The results of the COD and BOD concentration reduction with avocado peel carbon (APC) and commercial activated carbon (CAC) were compared and optimum operating conditions were determined for maximum reduction. Adsorption isotherm was also studied besides the calculation of optimum treatment parameters for maximum reduction of COD and BOD concentration from effluent of the coffee processing plant. The maximum percentage reduction of COD and BOD concentration under optimum operating conditions using APC was 98.20% and 99.18% respectively and with CAC this reduction was 99.02% and 99.35% respectively. As the adsorption capacity of APC is comparable with that of CAC for reduction of COD and BOD concentration, it could be a lucrative technique for treatment of domestic wastewater generated in decentralized sectors.     

An integrated treatment system for coffee processing wastewater using anaerobic and aerobic process

The experiment was conducted to develop an integrated treatment system for coffee processing wastewater (CPWW) through the combination of biomethanation with aeration and wetland plants treatment. The biomethanation was carried out at different hydraulic retention times (HRTs) using upflow anaerobic hybrid reactor (UAHR) and 18 h of HRT was found to be optimum. The maximum biochemical oxygen demand (BOD), chemical oxygen demand (COD) and total solids (TS) reduction were 66.0%, 61.0% and 58.0%, respectively with organic loading rate of 9.55 kg m^?3 day^?1. The reduction of pollution load of the wastewater by microbial action augmented by aeration resulted in the reduction of electrical conductivity (EC), BOD, COD, and total solids (TS). Continuous aeration of wastewater resulted in maximum reduction of BOD (74.6%), COD (68.6%) and TS (49.3%). The wetland plant, Typha latifolia reduced 85.4% and 78.0% of BOD and COD, respectively in biomethanated cum aerated CPWW.     

Growth of immobilised plant cells in reticulate polyurethane foam matrices

Summary An inoculum of initially freely suspended cell aggregates ofCapsicum frutescens was immobilised in porous polyurethane foam matrices. Subsequent growth and substrate consumption of these immobilised cells in batch culture were measured and compared with those of suspension cultures. The results showed that the maximum specific growth rate of freely suspended cells was slightly higher than that of immobilised cells but the overall growth patterns and final cell yields were similar.     

Rhodovulum sulfidophilum in the treatment and utilization of sardine processing wastewater

AIMS: Rhodovulum sulfidophilum was grown in settled undiluted and nonsterilized sardine processing wastewater (SPW). The aims were to evaluate the effects of inoculum size and media on the biomass production with simultaneous reduction of chemical oxygen demand (COD). METHODS AND RESULTS: Three levels of inoculum size (10, 20 and 30% v/v) developed in glutamate-malate media (GMM) or settled and undiluted SPW were compared. The highest biomass (4.8 g l-1) was obtained after 96-h culture with 20% (v/v) inoculum size, but the reduction in COD of SPW was the highest (85%) after 120-h culture with a 30% (v/v) inoculum developed in GMM. In cultures with inoculum developed in SPW the COD reduction in SPW was 79-83%. CONCLUSIONS, SIGNIFICANCE AND IMPACT OF THE STUDY: Inoculum developed in GMM supported good growth of Rv. sulfidophilum in settled undiluted SPW and subsequent reduction in COD. A conceptual model was proposed for the treatment and utilization of SPW.     

MICREDOX--development of a ferricyanide-mediated rapid biochemical oxygen demand method using an immobilised Proteus vulgaris biocomponent

Biochemical oxygen demand (BOD) is an international regulatory environmental index for monitoring organic pollutants in wastewater and the current legislated standard test for BOD monitoring requires 5 days to complete (BOD5 test). We are developing a rapid microbial technique, MICREDOX, for measuring BOD by eliminating oxygen and, instead, quantifying an equivalent biochemical co-substrate demand, the co-substrate being a redox mediator. Elevated concentrations of Proteus vulgaris, either as free cells or immobilised in Lentikat disks, were incubated with an excess of redox mediator (potassium hexacyanoferrate(III)) and organic substrate for 1h at 37 degrees C without oxygen. The addition of substrate increased the catabolic activity of the microorganisms and the accumulation of reduced mediator, which was subsequently re-oxidised at a working electrode generating a current quantifiable by a coulometric transducer. The recorded currents were converted to their BOD5 equivalent with the only assumption being a fixed conversion of substrate and known stoichiometry. Measurements are reported both for the BOD5 calibration standard solution (150 mg l(-1) glucose, 150 mg l(-1) glutamic acid) and for filtered effluent sampled from a wastewater treatment plant. The inclusion of a highly soluble mediator in place of oxygen facilitated a high ferricyanide concentration in the incubation, which in turn permitted increased concentrations of microorganisms to be used. This substantially reduced the incubation time, from 5 days to 1h, for the biological oxidation of substrates equivalent to those observed using the standard BOD5 test. Stoichiometric conversion efficiencies for the oxidation of the standard substrate by P. vulgaris were typically 60% for free cells and 35-50% for immobilised cells.     

Use of Rhodopseudomonas palustris P1 stimulated growth by fermented pineapple extract to treat latex rubber sheet wastewater to obtain single cell protein

Latex rubber sheet wastewater (non sterile wastewater: RAW) was treated efficiently using a stimulated Rhodopseudomonas palustris P1 inoculum with added fermented pineapple extract (FPE) under microaerobic light conditions. Optimization of wastewater treatment conditions using a central composite design (CCD) found that a 3 % stimulated P1 inoculum with 0.9 % added FPE and a 4-day retention time (RT) were the most suitable conditions. Calculations from CCD experiments predicted that a chemical oxygen demand (COD) of 3,005 mg/L could be 98 % removed, together with 79 % of suspended solids (SS) and 72 % of total sulfide (TtS). No H₂S was detected, production costs were low and single cell protein (SCP) was a by-product. The results of the verification test had an error of only 4–8 % and confirmed removal of COD (initial COD 2,742 mg/L), SS and TtS at 94 %, 75 % and 66 %, respectively. These values were less than the best set obtained from the CCD experiment (2 % stimulated P1 inoculum, 0.75 % FPE and 4 days RT); upon repeating, this set could reduce 96 % of the COD, 78 % SS and 71 % TtS. The treated wastewater met the standard guidelines for irrigation use and no H₂S was detected. The biomass obtaining after wastewater treatment from the best set consisted mostly of R. palustris P1; the biomass of this set had 65 % protein, 3 % fat, 8 % carbohydrate, 14 % ash and 10 % moisture. The results demonstrated that an inoculum of stimulated P1 grew well in RAW supplemented with FPE and could be considered to be an appropriate technology for effectively treating wastewater, with SCP as a by-product.     

Build-up and decline ofRhizoctonia solani inoculum under field conditions

Summary Inoculum potential ofRhizoctonia solani Kühn was studied in an infested carnation field during two successive growth seasons. This inoculum potential was expressed as diseased carnation plants in the field and diseased bean seedlings planted in soil samples. Disease incidence in the field soil samples increased during the first season, up to 60% and 100%, respectively. Removing the carnation plants and keeping the soil wet for 45 days, resulted in a sharp decline in inoculum potential. Both inoculum potential and disease incidence in carnations were lower after plant removal. The use of either methyl bromide or vapam resulted in complete control of the disease and reduced inoculum potential. Results suggest possible reduction ofR. solani inoculum by maintaining the soil moist between growth periods.     

Enhanced hydrogen production by Rhodopseudomonas palustris CQK 01 with ultra-sonication pretreatment in batch culture

In the present study, the photo-hydrogen production performances by Rhodopseudomonas palustris CQK 01 growing from the inoculated cells with ultra-sonication pretreatment (R. palustris CQK 01-USP) were experimentally investigated in batch culture and compared with that without pretreatment (R. palustris CQK 01-NP). It was found that the ultra-sonication pretreatment modified membrane morphology and broke up part of the cells, resulting in improvement of membrane permeability and bacterial activities and hence, helping the improvement of hydrogen production. The hydrogen production rate, hydrogen yield and energy conversion efficiency with R. palustris CQK 01-USP were increased to be nearly 2 times higher than that with R. palustris CQK 01-NP. The parametric study showed that under the conditions of initial glucose concentration 50 mmol/l, inoculum size 12%, illumination wavelength 590 nm, the photobioreactor with R. palustris CQK 01-USP obtained the optimal hydrogen production rate 0.54 mmol/l/h, hydrogen yield 1.2 mol-H₂/mol-glucose and energy conversion efficiency 9.03%.     

Bioremediation of an industrial effluent containing monocrotophos

Almost 30% of the precious agricultural output of India is lost owing to pest infestation. In India, pesticide consumption for protecting crops is about 3% of the total world consumption. Monocrotophos (MCP), an organophosphorus insecticide, is widely used to control insects on crops. Being readily water soluble and highly toxic, its removal from wastewater generated during manufacture becomes inevitable. Bioremediation of wastewater containing MCP by Arthrobacter atrocyaneus, Bacillus megaterium, and Pseudomonas mendocina was highest at pH 8.0, but maximum reduction in Chemical Oxygen Demand (COD) was at pH 7.0. Removal of MCP and reduction in COD by B. megaterium and Ps. mendocina were highest at 35°C, while with A. atrocyaneus, it was maximum at 30°C, under aerated culture condition and inoculum density of 10⁸ cells/ml. Use of pure cultures for bioremediation of effluent containing MCP appears to be the first such attempt. Received: 26 September 2001 / Accepted: 5 February 2002     

Adaptation ofSaccharomyces cerevisiae to solvents used in extractive fermentation

Summary The toxicities of tri-butyl phosphate (TBP) and 2-tert-butyl phenol (OTBP) on the growth ofSaccharomyces cerevisiae were investigated. The toxicity of TBP was reduced by using the inoculum adapted in the medium containing 0.1% (v/v) TBP. OTBP exerted no toxicity in a concentration up to 0.3% (v/v) by adaptation and adding nontoxic solvent 1% (v/v) di-butyl phthalate (DBP). The adaptation resulted in the reduction of hydrophobicity of the cell surface.     

Use of native aquatic macrophytes in the reduction of organic matter from dairy effluents

Considering the diversity and the unexplored potential of regional aquatic flora, this study aimed to identify and analyze the potential of native aquatic macrophytes to reduce the organic matter of dairy wastewater (DW) using experimental constructed wetlands. The dairy wastewater (DW) had an average chemical oxygen demand (COD) of 7414.63 mg/L and then was diluted to 3133.16 mg/L (D1) and to 2506.53 mg/L (D2). Total solids, COD, temperature, and pH analyses were performed, and the biochemical oxygen demand (BOD) was estimated from the COD values. The best performance in the reduction of the organic matter was observed for Polygonum sp. (87.5% COD and 79.6% BOD) and Eichhornia paniculata (90% COD and 83.7% BOD) at dilution D1, on the 8th day of the experiment. However, the highest total solids removal was observed for Polygonum sp. (32.2%), on the 4th day, at dilution D2. The total solid (TS) concentration has also increased starting from the 8th day of the experiment was observed which may have been due to the development of mosquito larvae and their mechanical removal by sieving, thus changing the steady state of the experimental systems. The macrophytes Polygonum sp. and E. paniculata were considered suitable for the reduction of organic matter of DW using constructed wetlands.     

Using reverse micelles as microreactor for hydrogen production by coupled systems of Nostoc / R. palustris and Anabaena / R. palustris

Uptake hydrogenase negative mutants of bloom forming cyanobacteria (Nostoc and Anabaena) and the fermentative bacteria Rhodopseudomonas palustris P₄ were used together for producing hydrogen within the reverse micelles fabricated by N-ethyl hexyl sodium sulfosuccinate (AOT) in isooctane and cetyl trimethyl ammonium bromide (CTAB) in benzene. The rate of H₂ production in AOT/isooctane reverse micellar system was found to be more promising in comparison to the CTAB/Benzene reverse micellar entrapment. After mutagenesis in 2.0% (v/v) ethyl methane sulphonate (EMS) mutants of Nostoc and Anabaena were selected on BG-11 plates (containing 2% agar) and then used for analysis of produced hydrogen. In comparison to the unmutated Nostoc with R. palustris (within AOT/isooctane) the coupled system of mutated Nostoc and R. palustris produced H₂ by 3.9-fold higher rate, which is 8.6 mmol H₂/h/mg protein. Whereas, mutated Anabaena coupled with R. palustris produced 4.8 times higher hydrogen production within (AOT)/isooctane reverse micelles in comparison to the unmutated Anabaena with R. palustris. Effect of nitrogen to carbon ratio (N/C) on hydrogen production was studied and Anabaena/R. palustris and Nostoc/R. palustris systems were, respectively, found to generate 11.2 and 9.8 mmol H₂/h/mg protein continuously for 3 days. Effects of temperature and light intensity were also investigated and we found that 32°C temperature and 1,000 Lux light intensity are the optimum values in these systems. Addition of sodium dithionite also resulted in further enhancement of the rate and duration of hydrogen production in both (mutated Nostoc/R. palustris and mutated Anabaena/R.␣palustris) systems.     

Decolorization of synthetic melanoidins-containing wastewater by a bacterial consortium

The presence of melanoidins in molasses wastewater leads to water pollution both due to its dark brown color and its COD contents. In this study, a bacterial consortium isolated from waterfall sediment was tested for its decolorization. The identification of culturable bacteria by 16S rDNA based approach showed that the consortium composed of Klebsiella oxytoca, Serratia mercescens, Citrobacter sp. and unknown bacterium. In the context of academic study, prevention on the difficulties of providing effluent as well as its variations in compositions, several synthetic media prepared with respect to color and COD contents based on analysis of molasses wastewater, i.e., Viandox sauce (13.5% v/v), caramel (30% w/v), beet molasses wastewater (41.5% v/v) and sugarcane molasses wastewater (20% v/v) were used for decolorization using consortium with color removal 9.5, 1.13, 8.02 and 17.5%, respectively, within 2 days. However, Viandox sauce was retained for further study. The effect of initial pH and Viandox concentration on decolorization and growth of bacterial consortium were further determined. The highest decolorization of 18.3% was achieved at pH 4 after 2 day of incubation. Experiments on fresh or used medium and used or fresh bacterial cells, led to conclusion that the limitation of decolorization was due to nutritional deficiency. The effect of aeration on decolorization was also carried out in 2 L laboratory-scale suspended cell bioreactor. The maximum decolorization was 19.3% with aeration at KLa = 2.5836 h⁻¹ (0.1 vvm).