Submerged anaerobic membrane bioreactor for wastewater treatment and energy generation.

Compared with conventional wastewater treatment processes, membrane bioreactors (MBRs) offer several advantages including high biodegradation efficiency, excellent effluent quality and smaller footprint. However, it has some limitations on account of its energy intensive operation. In recent years, there has been growing interest in use of anaerobic membrane bioreactors (AnMBRs) due to their potential advantages over aerobic systems, which include low sludge production and energy generation in terms of biogas. The aim of this study was to evaluate the performance of a submerged AnMBR for the treatment of synthetic wastewater having 4,759 mg/l chemical oxygen demand (COD). The COD removal efficiency was over 95% during the performance evaluation study. Treated effluent with COD concentration of 231 mg/l was obtained for 25.5 hours hydraulic retention time. The obtained total organic carbon concentrations in feed and permeate were 1,812 mg/l and 89 mg/l, respectively. An average biogas generation and yield were 25.77 l/d and 0.36 m3/kg COD, respectively. Evolution of trans-membrane pressure (TMP) as a function of time was studied and an average TMP of 15 kPa was found suitable to achieve membrane flux of 12.17 l/(m2h). Almost weekly back-flow chemical cleaning of the membrane was found necessary to control TMP within the permissible limit of 20 kPa.

A method to minimize the global warming and environmental pollution.

There has been continuous increase in the level of CO2 in atmosphere. Therefore, it is essential to develop an economical and convenient process to reduce the concentration of CO2 in the atmosphere. In this study, we have proposed an economical and efficient adsorption method to minimize the environmental CO2. A fluidized bed adsorption column was used, fabricated using cast iron sheet. The low prize pyrolyzed biochar prepared from farming biomass (crushed fine powder) was used as an adsorbent to adsorb CO2 from the mixture of air and CO2 (99.5% air and 0.5% CO2). The experimental observation was taken for the % removal of CO2 from the mixture of air and CO2, development of adsorption isotherm and to study the effect of pressure and inlet gas flow rate on the amount of CO2 adsorbed per kg of biochar. The exhausted (CO2 adsorbed) biochar from the fluidized column was tested as a fertilizer for the wheat crop and it has given near about 10% increase in the height of wheat crop within the first 10 days after sowing the wheat seeds. On the basis of this experimentation, we have proposed a hypothetical method, using above mentioned fluidized bed column and biochar as adsorbent to reduce the CO2 concentration in the highly polluted regions.