A study was conducted to formulate an optimized plan for upgrading an independent water system in a college campus where the available water source is from 5 groundwater wells with a maximum water supply capacity of 3000 m3/d but the water demand is much beyond this value for both potable and non-potable consumption. By water balance analysis, it was estimated that with the available fresh water consumed only for potable and related miscellaneous uses for 30000 people, the quantity of the reclaimed water could be enough to cover all the non-potable consumption. By material balance analysis, the pollutant loadings of organics, nitrogen and phosphorus were calculated and the requirements for pollutant removal corresponding with reuse purposes were evaluated. Considering the quality criteria of water reuse for lake landscaping, toilet flushing and gardening, and the demand for each water usage in the campus, a dual-quality reclaimed water supply scheme was proposed as (1) supply of lower quality reclaimed water for gardening and road sprinkling by upgrading the existing wastewater treatment facility of 1500 m3/d using conventional process, and (2) supply of higher quality reclaimed water for lake water replenishment and toilet flushing by implementing a new wastewater treatment facility of 2500 m3/d using MBR process. The independent water system thus optimized could sustain a total water consumption of more than 6000 m3/d using the 3000 m3/d source water. This provided a model case for future urban development in the water deficient region.

China has water shortage problems, especially in its northern region. The accelerated industrialization in the country further compounds the issue. A drastic corrective measure is the South-North Water Diversion Project which will transfer 40 billion m 3 /year of water from the south to the north. Other less dramatic abatement measures are water pollution control and wastewater reuse practices.Severn Trent Services has participated in three projects in China that involve tertiary treatment of wastewater for reuse. One project in Dalian utilizes a fixed-film biological treatment technology (SAF TM ) and a deep bed sand filter (DeepBed TM ) for upgrading a municipal secondary effluent for various industrial reuses. The other two projects employ the same treatment technologies for potential recycle of wastewater for internal reuses in two petrochemical complexes.The SAF TM treatment technology and DeepBed TM filter system were proven to be technically efficient and cost effective for upgrading secondary effluent for reuse. The Dalian reuse plant with a capacity of 20,000 m 3 /day flow is producing a high quality reusable effluent with NH 4 -N at <1 mg/L, TSS < 1 mg/L and COD < 40 mg/L. The treatment plant owner is satisfied with an investment return of less than 3 years payback period. The end users realize about 60% cost savings by using the tertiary treated wastewater in place of potable water. The City of Dalian preserves the precious drinking water for domestic consumption and has sufficient fresh water to entice foreign investments to Dalian. It is a perfect model of a win-win policy.The treatment technology is also applicable to the upgrade of industrial wastewater for reuse. The pilot study at PetroChina Jinxi Petrochemical Plant No. 5 demonstrated that the technology was able to produce a high quality effluent for reuse with less than 1 mg/L of NH 4 -N, 5 mg/L of TSS and 80 mg/L of COD. If a COD standard of 40 mg/L is absolutely required for cooling water makeup, a physical/chemical treatment would have to be added.PetroChina Harbin Petrochemical Plant has an existing secondary activated sludge process and a tertiary treatment facility, which consists of chemical coagulation, sedimentation, granular filtration and granular activated carbon adsorption. The existing treatment plant cannot effectively remove ammonium nitrogen from the wastewater; plant effluent has an average ammonium nitrogen concentration of about 150 mg/L. The SAF TM process was able to nitrify the ammonium nitrogen to meet the reuse requirement of 1 mg/L or a discharge limit of 50 mg/L.