Decentralized Methods of Water Treatment for Reuse of Residential Gray Water

Water shortages continue to cause negative economic, environmental, and social effects. This could be partially solved by reducing residential water consumption. This could be achieved by recycling graywater through an on-site graywater recycling system. Such a system would need to treat graywater to meet local water quality standards, be able to treat the graywater load from a typical home, be compact enough to fit in or near a home, and be relatively affordable. Three systems intended to treat residential graywater were examined: a drawer compacted sand filter, a semi-batch vertical flow wetland, and a moving bed biofilm membrane bioreactor. After an analysis of the three solutions, the semi-batch vertical flow wetland was recognized as the best graywater recycling system to use in residential buildings. This system produced treated graywater with the highest water quality and that contained no detectable escherichia coli. This system also was compact, and could process the highest amount of graywater. If successful, this system could help residential graywater recycling become more common and therefore reduce residential water consumption. This could help reduce the severity of water shortages and the negative effects associated with them.

Using numerical simulation of a one stage vertical flow wetland to optimize the depth of a zeolite layer

This simulation study investigates the treatment performance of a compact French vertical flow wetland using a zeolite layer in order to increase ammonium nitrogen removal. For the modelling exercise, the biokinetic model CW2D of the HYDRUS Wetland Module is used. The calibrated model is able to predict the effect of different depths of the zeolite layer on ammonium nitrogen removal in order to optimize the design of the system. For the model calibration, the hydraulic effluent flow rates as well as influent and effluent concentrations of chemical oxygen demand (COD) and NH4-N have been measured. To model the adsorption capacity of zeolite, Freundlich isotherms have been used. The results present the simulated treatment performance with three different depths of the zeolite layer, 10 cm (default), 15 cm and 20 cm, respectively. The increase of the zeolite layer leads to a significant decrease of the simulated NH4-N effluent concentration.

Solar Biogas Digester and Wetland-Pond System for Rural Wastewater Treatment

Solar biogas digester and wetland-pond system treated the wastewater for the rural about 60 families. The system comprised a solar anaerobic baffle digester, an anaerobic filter, a subsurface vertical flow wetland, and an eco pond. The four units were connected in series. The solar digester and the filter produced enough biogas evenly in whole year and provided 80-91% total suspended solids (TSS) removal. The wetland-pond developed aquatic crops, fisheries and waterfowl aquaculture. In this artificial ecosystem, bacterial oxidization, algae photosynthesis and food web degradation greatly reduced COD, BOD5, TN, NH4-N, TP, and pH of water.