Collective removal of phenol and ammonia in a moving bed biofilm reactor using modified bio-carriers: Process optimization and kinetic study.

The performance of a moving bed biofilm reactor (MBBR) with bio-carriers made of polypropylene-polyurethane foam (PP-PUF) was evaluated for the collective removal of phenol and ammonia. Three independent variables, including pH (5.0-8.0), retention time (2.0-12.0 h), and airflow rate (0.8-3.5 L/min) were optimized using central composite design (CCD) of response surface methodology (RSM). The maximum removal of phenol and ammonia was obtained to be 92.6, and 91.8%, respectively, in addition to the removal of 72.3% in the chemical oxygen demand (COD) level at optimum conditions. First-order and second-order kinetic models were analyzed to evaluate the pollutants removal kinetics in a MBBR. Finally, a second-order model was found to be appropriate for predicting reaction kinetics. The values of second-order rate constants were obtained to be 2.35, 0.25, and 1.85 L2/gVSS gCOD h for phenol, COD, and ammonia removal, respectively.

Bioremediation of Congo red dye in immobilized batch and continuous packed bed bioreactor by Brevibacillus parabrevis using coconut shell bio-char.

In the present study, bacterial species capable of degrading colour waste were isolated from the water bodies located near the carpet cluster in the Bhadohi district of U.P., India. Among the isolated species best one was selected on the basis of its capability to degrade Congo red in batch experiments using NaCl-Yeast as the nutrient media and further it was identified as Brevibacillus parabrevis using 16S rDNA sequencing. The process parameters were optimized for maximum degradation in batch experiments and found out to be: Inoculum size: 3 ml, Temperature: 30 °C, Time: 6 days leading to a removal of 95.71% of dye sample. The experiment showed that bacteria immobilized with coconut shell biochar in continuous mode showed much better degradation than batch study without immobilization. The kinetics parameters µmax, Ks, and µmaxKs were found to be 0.461 per day, 39.44 mg/day, and 0.0117 L/mg/day using Monod model.

Biodegradation and kinetic study of benzene in bioreactor packed with PUF and alginate beads and immobilized with Bacillus sp. M3.

Benzene removal in free and immobilized cells on polyurethane foam (PUF) and polyvinyl alcohol (PVA)-alginate beads was studied using an indigenous soil bacterium Bacillus sp. M3 isolated from petroleum-contaminated soil. The important process parameters (pH, temperature and inoculums size) were optimized and found to be 7, 37°C and 6.0×108CFU/mL, respectively. Benzene removals were observed to be 70, 84 and 90% within 9days in a free cell, immobilized PVA-alginate beads and PUF, respectively under optimum operating conditions. FT-IR and GC-MS analysis confirm the presence of phenol, 1,2-benzenediol, hydroquinone and benzoate as metabolites. The important kinetic parameter ratios (µmax/Ks; L/mg·day) calculated using Monod model was found to be 0.00123 for free cell, 0.00159 for immobilized alginate beads and 0.002016 for immobilized PUF. Similarly inhibition constants (Ki; mg/L) calculated using Andrew-Haldane model was found to be 435.84 for free cell, 664.25 for immobilized alginate beads and 724.93 for immobilized PUF.

Biofiltration of xylene using wood charcoal as the biofilter media under transient and high loading conditions.

The main objective of this study was to evaluate the performance of wood charcoal as biofilter media under transient and high loading condition. Biofiltration of xylene was investigated for 150days in a laboratory scale unit packed with wood charcoal and inoculated with mixed microbial culture at the xylene loading rates ranged from 12 to 553gm-3h-1. The kinetic analysis of the xylene revealed absence of substrate inhibition and possibility of achieving higher elimination under optimum condition. The pH, temperature, pressure drop and CO2 production rate were regularly monitored during the experiments. Throughout experimental period, the removal efficiency (RE) was found to be in the range of 65-98.7% and the maximum elimination capacity (EC) was 405.7gm-3h-1. Molecular characterization results show Bacillus sp. as dominating microbial group in the biofilm.

Performance evaluation of Malathion biodegradation in batch and continuous packed bed bioreactor (PBBR).

The aim of this work was to study the biodegradation of Malathion in batch and continuous packed bed (Polyurethane foam; PUF) bioreactor (PBBR). After 10days, 89% Malathion removal was observed in batch PBBR. Continuous PBBR was operated at various flow rates (5-30mL/h) under optimum condition over a period of 75days. Inlet loading rates and elimination capacities were observed in the range of 36-216 and 7.20-145.4mg/L/day with an average removal efficiency of more than 90% under steady state conditions. GC/MS analysis confirms phosphorodithionicacid,O,O,S-trimethylester and diethylmercaptosuccinate as metabolites. Biodegradation of Malathion under inhibitory and non-inhibitory conditions was studied using Monod and Andrew-Haldane models and the kinetic constants were calculated and found to be µmax: 0.271 per day; Ks: 126.3mg/L using Monod and µmax: 0.315 per day; Ks: 151.32mg/L; Ki: 594.75mg/L using Andrew-Haldane models.

Treatment of waste gas containing low concentration of dimethyl sulphide (DMS) in a bench-scale biofilter.

Biological treatment of dimethyl sulphide (DMS) was investigated in a bench-scale biofilter, packed with compost along with wood chips, and enriched with DMS degrading microorganism Bacillus sphaericus. The biofilter could remove 62-74% of the inlet DMS, at an optimum loading of 0.484 g/m(3)/h with optimum empty bed contact time (EBCT) of 384 s and an average moisture range of 65-70%. The biodegradative products of DMS were sulphide, thiosulphate and sulphate. Evaluation of microbiological status of the biofilter indicated the presence of other bacterial cultures viz. Paenibacillus polymyxa, and Bacillus megaterium, besides B. sphaericus.

Distributions of metals in the food web of fishponds of Kolleru Lake, India.

The distributions of trace metals (Pb, Cd, Cr Mn, Zn and Cu) in water, sediment, plankton and four fish species (Labeo rohita, Catla catla, Pangasius pangasius and Cirrhinus mrigala) from fishponds of Kolleru Lake, India were determined using atomic absorption spectroscopy. The concentrations of lead (0.01-0.03mg/l) and copper (0.01-0.08mg/l) in water and cadmium (3.0-9.0mg/kg), chromium (47-211mg/kg) and copper (10-64mg/kg) in sediment were above the EPA threshold effects level (TEL) and are of biological concern. The abundance orders of metals were Mn>Cd>Cu>Pb in water, Mn>Cr>Zn>Cu >Pb>Cd in sediment and Cu>Mn>Cr>Zn>Pb>Cd in plankton. The concentrations of the metals in the muscles of these four fish species apparently decrease in the order Zn>Cu>Cr>Mn=Pb>Cd and were well below WHO permissible limits that were safe for human consumption.

Modeling and Monte Carlo simulation of TCDD transport in a river.

A one-dimensional water quality model to assess the long-term fate of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in three compartments (water, sediment, fish) of a river has been developed using the literature data on various model parameters. The transient deterministic model with constant or nonrandom parameters is solved numerically by the method of orthogonal collocation, while an analytical solution is developed for the steady-state model. The impact of uncertainty in several model parameters has been studied by means of Monte Carlo simulations assuming that the uncertain parameters are uncorrelated and can be modeled by three probability distributions (uniform, normal and lognormal). For the case of a high TCDD discharge into a small, shallow river, we find that the maximum TCDD contents of water and fish are well below the prescribed safe limits. We also find that the effects of uncertainty on water quality metrics are quite complex or nonintuitive and can be substantial. This is especially true for TCDD in fish, which can be higher by as much as 50-70% than the deterministic predictions, if the parameter uncertainties follow uniform distributions.

Characterization of drowning by diatom test.

Examination by the diatom test, of different organs of corpses of individuals who died of drowning revealed the presence of frustules in all the visceral organs. Diatom load of different organs was found to be positively related with breadth/diameter of the frustule. Relatively larger diatoms were encountered in the lungs, heart and kidneys as compared to the other organs. Smaller diatoms up to 10 mu diameter were found in the brain, and bone marrow samples. However, diatoms were also recovered from the lungs, heart and kidneys of corpses of individuals in whom the cause of death was not drowning. Brain and bone marrow were considered reliable samples for executing the diatom test.

Inhibition of cytokinesis by lead (Pb2+) in a centric diatom.

Effect of inorganic and organo lead has been studied on the mitosis of a centric diatom Cyclotella meneghiniana f. unipunctata. Binucleate cells were formed in the presence of different concentrations of Pb2+ (1.0, 2.0, 3.0 and 5.0 mM) due to inhibition of cell plate formation. Lead at 5.0 mM concentration was more inhibitory than the other concentrations. Organo lead was a powerful depressant of cytokinesis than inorganic lead. Failure of cytokinesis might be due to disruption of microtubules. Formation of distinct nuclei delayed post incubation cell divisions suggest partial damage of mitotic spindles.