Potential of wastewater grown algae for biodiesel production and CO2 sequestration

Algae have been proposed as a potential renewable fuel source. Photosynthetic CO2 fixation to substrates that can be converted to biodiesel by microalgae is thought to be a feasible technology with energy-saving and environment-friendly approach. In the present study, potential of microalgae, from wastewater stabilization pond, as a feedstock for biodiesel production and CO2 sequestration was evaluated. Mixed algae sample showed the highest CO2 fixation rate, followed by Chlorella sp., Scenedesmus incrassatulus, Scenedesmus dimorphus and Chroococcus cohaerens (2.807, 1.627, 1.501, 1.270 and 0.786 g L-1 d-1, respectively). Nile red stain was used for detection of lipid in microalgal sample which was further extracted and analysed by gas chromatography (GC). The main fatty acids present in the mixed algae sample were fatty acids with C14–C18 (>98%) that are generated after natural CO2 sequestration. At ambient CO2 concentration, total fatty acid methyl esters (FAME) mainly comprised of myristic acid (C14:0), 0.0718%; palmitic acid (C16:0), 2.558%; octadecenoic acid (C18:1), 28.98% and linoleic acid (C18:2), 12.54% which makes the microalgal biomass a suitable feedstock for biodiesel production and CO2 mitigation.Keywords: Biodiesel, carbon dioxide fixation, fatty acid profile, microalgae, wastewater stabilization pondAfrican Journal of Biotechnology Vol. 12(20), pp. 2939-294

Treatment of waste gas containing low concentration of dimethyl sulphide in a high performance biotrickling filter

1018-1023A bench-scale biotrickling filter was operated in the laboratory for the treatment of dimethyl sulphide (DMS). The biotrickling filter was packed with pre-sterilized polyurethane foam and seeded with biomass developed from garden soil enriched with DMS. The biotrickling filter was operated for the generation of process parameters. The biotrickling filter could remove an average removal efficiency of 40.95 % at an effective bed contact time of 84 sec with an average loading rate of 0.56 mg/m3/h. Evaluation of microbiological status of the biotrickling filter indicated the presence of other bacterial cultures viz. Paenibacillus polymyxa, and Bacillus megaterium, besides Bacillus sphaericus.</i

Growth of Pseudomonas and Bacillus biofilms on pretreated polypropylene surface

Unpretreated and Aquaregia, Fenton, thermal and short UV pretreated polypropylene films of 0.05 mm thickness were subjected to biodegradation in vitro in minimal medium with four soil cultures, namely Pseudomonas azotoformans, Pseudomonas stutzeri, Bacillus subtilis and Bacillus flexus separately for 12 months. P. azotoformans and B. subtilis are relatively hydrophobic, produce biosurfactant and form biofilm on the polymer with comparatively higher carbohydrate and protein than the other two organisms. All the organisms make use of the polymer as their carbon source. Highest weight loss (2.5%) was observed in the case of short UV treated polymer exposed to B. flexus after one year. The carbonyl indices decreased in one year in the case of pretreated polymer and increased in the case of untreated polymer, indicating only abiotic oxidation in the absence of pretreatment. Increase in surface energy indicated that the polymer became more hydrophilic when compared to the original. P. stutzeri had marginal effect on the polymer

Ozone treatment of sulfamethoxazole in aqueous matrix and toxicity of its degradation products on Pseudomonas aeruginosa and Enterobacter xiangfangensis species

Sulfamethoxazole (SMX) is extensively used antibiotic and residue of SMX has been found in surface and drinking water in ng/L concentration. The advance oxidation process such as ozonation has been proposed for removal of SMX into its possible readily biodegradable intermediates and also limits its impact on the environment. About 20 g/h of ozone dosage used for treatment of sulfamethoxazole (four different concentrations of SMX 10 ppm, 20 ppm, 30 ppm and 40 ppm) resulted in 99 % removal within 60 minutes of ozonation with the leftover of its degradation products. However, the toxicity of degradation products of SMX formed after ozone treatment on soil microorganism (Pseudomonas aeruginosa and Enterobacter xiangfangensis) has not been reported. In the current study toxicity of degradation products using MTT assay has been reported. The study revealed that degradation product of SMX not showing any significant cytotoxic effect on the soil micro-organism compared to pure SMX

Advances and perspective in bioremediation of polychlorinated biphenyl-contaminated soils

In recent years, microbial degradation and bioremediation approaches of polychlorinated biphenyls (PCBs) have been studied extensively considering their toxicity, carcinogenicity and persistency potential in the environment. In this direction, different catabolic enzymes have been identified and reported for biodegradation of different PCB congeners along with optimization of biological processes. A genome analysis of PCB-degrading bacteria has led in an improved understanding of their metabolic potential and adaptation to stressful conditions. However, many stones in this area are left unturned. For example, the role and diversity of uncultivable microbes in PCB degradation are still not fully understood. Improved knowledge and understanding on this front will open up new avenues for improved bioremediation technologies which will bring economic, environmental and societal benefits. This article highlights on recent advances in bioremediation of PCBs in soil. It is demonstrated that bioremediation is the most effective and innovative technology which includes biostimulation, bioaugmentation, phytoremediation and rhizoremediation and acts as a model solution for pollution abatement. More recently, transgenic plants and genetically modified microorganisms have proved to be revolutionary in the bioremediation of PCBs. Additionally, other important aspects such as pretreatment using chemical/physical agents for enhanced biodegradation are also addressed. Efforts have been made to identify challenges, research gaps and necessary approaches which in future, can be harnessed for successful use of bioremediation under field conditions. Emphases have been given on the quality/efficiency of bioremediation technology and its related cost which determines its ultimate acceptability