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Rainwater harvesting has become an important strategy to achieve the goal of sustainable development in urban areas. The latest emerged gravity driven micro-filtration technology can effectively reduce turbidity and bacteria to a very low level but still have disadvantages of low removal of dissolved organic substances and low permeate flux. An innovative gravity driven micro-filtration technique using ceramic flat sheet membrane as filter module was established and introduced to the treatment of rainwater that was harvested from a typical official building in GuangZhou, South China. The performance of this process has been evaluated in terms of pollutants (e.g. pH, turbidity, total dissolved solids (TDS), CODcr, NH3-N, DOC,UV254, total Coliforms and E.coli) removal efficiency, and the permeate flux profiles. Results shows that the removal rates of turbidity, TDS, CODcr, NH3-N, DOC,UV254, Coliforms and E.coli were 92.2%, 91.9%, 65.5%, 42.6%, 76.9%, 61%, 96.9% and 95.5%, respectively. The GDM system can run continuously for 60 days without back washing, and the permeate flux stabilized at 22~45 L/(m²·h) under a constant water head of 20 kPa. Experimental results demonstrated that the GDM system employing a ceramic flat membrane can significantly improve the organics removal in rainwater.

Gravity-driven rainwater harvesting (RWH) system showcases a promising alternative solution to reduce energy consumption in rainwater recycling. However, the economic efficiency is one of the most concerns with regard to the adoption of this green infrastructure. In this study, a commercial official building has a rooftop area of 1600 m 2 and with 560 inhabitants was assumed to apply two configurations of RWH

This study investigated the removal of phthalic acid esters (PAEs) from aqueous solution by the biological activated carbon (BAC) process. PAEs, such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, and di(2-ethylhexyl) phthalate, were effectively removed at a 40 mg/L activated carbon dosage by emergency activated carbon treatment for excessive amounts of PAEs. The optimal BAC process parameters were an initial PAE concentration of 10 μg/L and an empty bed contact time of 10 min. Results further showed that with higher summer temperatures, mature biofilms were formed, and CODMn, NH3-N and PAE removal efficiency tended to stabilize for approximately 1 month. During stable BAC operation, biodegradation was the primary mechanism.

Rainwater harvesting (RWH) systems are one of the most promising technologies for water supply and economic viability is often a major barrier to their implementation. In order to develop a generic method to assess the economic viability of decentralized RWH systems at a regional level, this paper investigates the effect of variations in building characteristics on the economic performance of rainwater harvesting systems in regions where the water tariffs and rainfall distribution characteristics are fixed. This paper simulated the financial efficiency (expressed as a benefit-cost ratio) of a large number of decentralized RWH systems in Guangzhou, China. It is found that the financial efficiency of RWH systems is closely related to the catchment fraction (the ratio of rainfall catchment surface to total floor area). Based on this dimensionless parameter, explicit equations expressing the financial efficiency of RWH systems were derived using a nonlinear regression method. In addition, the validity of the analytical equations was verified by the root mean square error test, normality test, and error distribution test. This analytical solution provides a simple and generic method for forecasting the investment potential of rainwater harvesting systems. The developed methodology can also be adapted to other regions merely the variations of local water price and rainfall data need to be considered.

The collection and reuse of greywater has become an important strategy for achieving the goal of sustainable development. In this work, an integrated preliminary settlement and filtration process was developed for treating shower water which was obtained from a college bathroom toilet. The system's pollutant removal efficiency was examined for three different filter media: manganese sand, quartz sand and ceramsite. The results showed that for ceramsite, the average removal of turbidity, CODcr, NH3-N, and anionic surfactant was 93.3%, 68.6%, 78.9, and 83.5% respectively. For manganese sand, the values were 84.6%, 61.5%, 57.8 and 59%, while for quartz, they were 88.9%, 47.9%, 39.5% and 51.9%. A cost benefit analysis revealed that the payback period of greywater recycling systems ranges from 3.16–5.30 years and benefit-cost ratios are in the range of 1.23–1.67, depending on tank size. The proposed system provides a new strategy for enhancing water-use efficiency in buildings in a more decentralised way.

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