A study on the performance of a pilot scale A2/0-MBR system in treating domestic wastewater.

Phosphorus and nitrogen are the important eutrophication nutrients. They were removed in the anaerobic/anoxic/oxic (A2/O) system through biologically. The use of pilot scale A2/O systems with immersed membranes in removing nutrients phosphorus and nitrogen were investigated over a period of 150 days. The A2/O membrane bio reactor (MBR) was operated at a flux of 17 LMH. The designed flux was increased stepwise over a period of one week. The reactor was operated with the mixed liquid suspended solids (MLSS) concentrations in the range of 7000-8000 mg l-1. The phosphorus removal was found to be in the range of 74-84%. The ammonification was completed in the aerobic zone and the ammonia concentration was almost nil. Nitrate concentration in the anoxic zone was found to be in the range of 0.3-1.6 mg l-1 indicating efficient denitrification. The nitrogen removal efficiency of the A2/O-MBR system was in the range of 68 to 75%. The chemical oxygen demand (COD) in the effluent was in the range of 8-5 mgl-1 indicating the efficiency of membrane. During the period of reactor operation transmembrane pressure (TMP) of the reactor increased slowly from 0 to 6 -cmHg over a period of 150 days.

Biomanagement of sago-sludge using an earthworm, Lampito mauritii.

In the present study vermicomposting was carried out at three different concentrations of sago-sludge namely 50, 75 and 100% with an indigenous earthworm, Lampito mauritii for a period of 50 days. The fecundity of earthworm Lampito mauritii was found to be high in 50%. At the end of 50 days composting period. There were about 12 cocoons, 5 juveniles and 2 nonclitellates appeared at 50% sago-sludge concentration. The microbial analysis showed that after 40 days of composting their population stabilized and further increase in composting period did not increase their population size. Chemical analysis of Lampito mauritii worked substrates showed there is a step wise increase of nitrogen and phosphorus. The fold increase of phosphorus and nitrogen were found to be high for sago-sludge undergoing vermicomposting than the control. From the initial value of 1.8, 1.4 and 0.5 mg kg(-1) total nitrogen increased in a stepwise manner and reached a value of 5.8, 3.9 and 2.3 mg kg(-1), respectively for vermicomposting at 50, 75 and 100%. During composting the organic carbon decreased from its initial value of 56, 74 and 107 mg kg(-1) to 15, 25 and 58 mg kg(-1) for vermicomposting and 34, 45 and 72 mg kg(-1) for 50, 70 and 100% control, respectively. The results indicate that 50% and 75% concentration of sludge mixed with bedding material was ideal for the vermicomposting.

Biomanagement of sago-sludge using an earthworm, Eudrilus eugeniae.

Sago, the tapioca starch is manufactured by over 800 small-scale units located in the Salem district, Tamil Nadu, India. During the processing of sago it generates huge quantities of biodegradable solid waste, as crushed tubers. In present study an attempt was made to convert these biodegradable solid sago tubers into value added compost using an exotic earthworm, Eudrilus eugeniae. The experiments were carried out in a plastic tray at various concentrations of sago-sludge (50% 75% and 100%) for a period of 90 days. During the vermicomposting, data were collected on life form (cocoon, non clitellates, clitellates) of earthworm and it was found to be high in 50% followed by 75% and 100% concentrations. Chemical analysis of worked substrates showed a step wise increase of nitrogen and phosphorus. The fold increase of phosphorus and nitrogen were found to be high for sago-sludge undergoing vermicomposting than the control. During the composting period the organic carbon decreased from its initial value of 58, 76 and 107 mg/kg to 21, 24 and 65 mg/kg for 50, 70 and 100%, respectively The microbial analysis showed that after 75 days of composting, their population stabilized and further increase in composting period did not increase their population size. The results indicate that 50% and 75% concentration of sludge mixed with bedding material was ideal for the vermicomposting.

Solid state biomethanation of fruit wastes.

Overtones of fruit wastes accumulate daily in the city of Chennai, India and there is an urgent need to develop, assess and use ecofriendly methods to dispose them. Presently an attempt has been made to study solid state biomethanation of fruit wastes using a laboratory scale anaerobic digester Fruit wastes containing 3%, 4% and 5% solids were used for experimentation. Daily and cumulative production of biogas produced during the study was recorded. Increase in nitrogen, phosphorus and potassium content in the feed was observed during the digestion. During the study the biogas generation increased with increase in total solids. While the gas generation was 0.006 m3/day/m3 of the reactor volume when the solid content was 3% the corresponding values for 4% and 5% solids were 0.27and 0.35 m3 respectively Varying TS 3% to 4% has no effect on fermentation stability and pH remained between 6.8 and 7.4, but an inhibition of methanogenic bacteria was observed for TS 5%. The overall performance of the reactor was depressed by changing feed concentration from 3% to 5%. Experiments with 4% initial solid contend was ideal for solid-state biomethanation.