Waste stabilization pond is an artificial ecosystem; its performance is governed by the nature of the biological communities it supports. These are primarily used as secondary effluent treatment plants to polish the effluents. However, they are also used to treat the raw sewage and industrial effluents. In the present study, the functioning of a waste stabilization pond system from an industrial complex located in Goa was taken up. The raw waste released by the industrial complex and the final effluent released from the stabilization ponds were analyzed for pH, dissolved oxygen (DO), biological oxygen demand, phosphate content, chlorophyll content, and algal diversity and density. Also, the activities of the enzymes catalase and phosphatase were measured. The study was carried out for a period of 1 year and the data covering pre-monsoon, monsoon, and post-monsoon seasons are tabulated. The study revealed that DO, chlorophyll content, and algal count were maximum during pre-monsoon when compared to monsoon and post-monsoon. Similarly, maximum enzymatic activity was recorded during pre-monsoon and also maximum removal of biological oxygen demand and phosphate was recorded during this period than in monsoon and post-monsoon.

Abstract-Biodiesel is consider as a potential alternative fuel for compression ignition engines. These are obtained from various resources. However, the usage of biodiesel blend in high percentages in compression ignition may cause some technical problems because of their higher viscosity, high pour point, and low volatility. Ethanol can be used as a fuel extender to enable the use of the higher percentage of biodiesel in CI engine. Blends of ethanol-animal fat oil biodiesel-diesel were prepared and experimental studies have been carried out. We have found that B40E20 fuel blend (40% biodiesel and 20 % ethanol in diesel) reduces the specific fuel consumption and improves brake thermal efficiency of the engine compared to B40 fuel blend. We observed that fuel characteristics improved considerably with the addition of ethanol to biodiesel. Emissions of CO, HC and smoke reduced while CO 2 emissions were increased due to more complete combustion of the blend.

Plastics have been one of the fastest growing materials due to versatility, wide range of applications and relatively at low. As the duration of useful life of plastic products is relatively small, a vast plastics waste stream is creating a serious environmental problem. Disposal of post-consumer plastics is being a serious constraint, a considerable demand for alternatives to disposal or land filling. Among the alternatives, production of liquid fuel would be a better alternative as the calorific value of plastics is comparable to that of fuels, around 40 MJ/kg. Other properties of the oil derived from waste plastics were also similar to the petroleum-based diesel. In the present work, blends of 20%, 40%, 60%, 80% Waste Plastic Oil (WPO) with diesel and 100% WPO are considered to investigate the performance, and emission characteristics in an existing diesel engine. For better understanding of the results, an injection time of 230 BTDC, 200 bar fuel injection pressure, and a 3 holes injector is used throughout the investigation. Some better performance and emission characteristics were observed from all the blend ratios. However, 20% WPO and 80% diesel blend gave better results as compared to other waste plastic oil blends.