Full Description

The South Texas coastal area has limited fresh water resources. Any feasible project that affords reduction in the amount of required freshwater diversions supporting the area population and economy will be irresistible to the regional water supplier, the San Patricio Municipal Water District, and its customers. Continuing studies identified a potential project, conveying wastewater effluent and stabilized biosolids from the City of Aransas Pass to dry and dusty tailings beds at the Reynolds Metals Co. alumina plant 8 miles (12.7 km) away. These tailings beds are storage areas for the bauxite residue remaining after the Bayer process removes aluminum oxide. The residue is very high in iron, sterile and on windy days very dusty. Research had indicated that the combination of fresh water and biosolids could convert this sterile, dusty area into a productive wildlife area, while returning most of the fresh water flow to the industrial process. A side benefit would be the leaching out and recovery of process materials in the stored tailings. To solve this situation, it was proposed to substitute the treated municipal wastewater effluent for the recycled water being used for dust control. Multiple planning and study sessions followed. Decisions made early in the process included the following: invite the Texas Water Development Board (TWDB, planning and funding) and the Texas Natural Resource Conservation Commission (TNRCC, permitting and regulation) to participate in the project at regional and state levels; involve the staff of local municipalities, the District and Reynolds Metals Co. in the initial and continuing planning efforts; invite review of progress of the project by groups with wider conservation and environmental interests; utilize locally available research capabilities, primarily Texas A and, arrange for tours of the tailings area by all interested parties. Early results were impressive. Reynolds' interest in the project was not limited to obtaining freshwater for dust control. As the idea developed, they could see that seepage from the tailings area would show up as increased flow in the ditches surrounding the tailings dikes. This water is directed to a sump reservoir and enters the process water stream to the alumina plant. One of the earliest pilot testing projects was their diversion of the effluent from a small sanitary sewage treatment plant to an area of the tailings beds next to the outer dike. Once recirculated water irrigation was stopped and the effluent applied, everything started to grow. Many plant species were placed in the area and all did well. Seepage through the dike adjacent to the area was monitored and increased as anticipated. The exact scope of the project developed a piece at a time over several years. The pilot testing program proved the concept of replacing recirculated water for dust control on the tailings beds with treated effluent. Experiments with organic soil amendments led to the idea of transporting and disposing of stabilized wastewater biosolids with the effluent flow. The availability of the Aransas Pass facility, the lack of restrictions on moving the effluent discharge location and the economics and dependability of the supply proved to be a winning combination for all participants. A total of 290 million gallons of water per year could be reclaimed, of which 260 million gallons would replace a similar amount of demand from the surface water supply. A brackish water tidal area project in a park adjacent to the City of Aransas Pass wastewater treatment plant would use the difference of 30 million gallons per year. Reynolds Metals Co. could receive all of the stabilized biosolids (approximately 230 tons/year) produced by the Aransas Pass plant for use as a soil amendment and the cost to the city of transportation and disposal of this material would be eliminated.

Product Details

Edition: Vol. - No. Published: 01/01/2002 Number of Pages: 6File Size: 1 file , 190 KB