The Upper Occoquan Sewage Authority (UOSA) Water Reclamation Plant, Centreville, Virginia, is a state-of-the-art wastewater treatment plant that was created to treat area wastewater and provide protection for the Occoquan Reservoir. This study investigated UOSA's unit processes as barriers to pathogenic as well as alternative and traditional indicator microorganisms. Samples were collected once a month for 1 year from eight sites within UOSA's advanced wastewater reclamation plant. The eight sites were monitored for indicator bacteria total and fecal coliforms, enterococci, Clostridium, coliphage (the virus that infects Escherichia coli), human enteroviruses, and enteric protozoa.Overall, the plant was able to achieve a 5-to 7-log 10 reduction of bacteria, 5-log 10 reduction of enteroviruses, 4-log 10 reduction for Clostridium, and 4.6-log 10 reduction of protozoa. Total coliforms, enterococci, Clostridium, coliphage, Cryptosporidium, and Giardia were all detected in four or fewer samples of the fi nal effl uent. No enteroviruses or fecal coliforms were detected in the fi nal effl uent. The microbiological quality of reclaimed water and the reservoir water were compared. In every case, the treated wastewater was of a better quality than the ambient water in the reservoir, thus indicating that the reclaimed water will not adversely affect the water quality for downstream users. Water Environ. Res., 73, 711 (2001).

The purpose of this study was to examine the feasibility of using dual water systems to furnish high quality water for drinking and other home uses. Dual water systems are defined as those involving distribution of two grades of water to consumers through independent pipe networks. The study also included the development of comparative costs of complete water systems that employ conventional and dual distribution systems.

The City of Tampa in the Southwest portion of Florida is examining the development of an advanced treatment facility for supplementing their potable water supply with highly treated reclaimed water. Full-scale microbiological monitoring of a similar treatment train demonstrated that the high-pH chemical treatment process was an effective barrier for removal and inactivation of viruses (99.99%), bacteria (99.9999%) and enteric protozoa (99.9%). A constructed pilot plant and bench-scale studies of the high-pH chemical process demonstrated that the removal of Cryptosporidium oocysts was due to physical removal and no inactivation was shown with up to 180 minutes exposure at a pH of 11.2. Combination of high-pH chemical treatment and chlorination were also ineffective at kill of Cryptosporidium oocysts.

A pollution problem in the Washington, D.C., area sparked this study of natural and plant‐treatment processes for removing viruses, trace organics, heavy metals, and nutrients from reservoir water in order to make it safe for recreation and drinking.

This article begins by presenting an overview of past research on upflow filtration. The article then discusses small‐scale laboratory upflow filtration studies conducted at the Lawrence, Kansas, Water Treatment Plant. The objective of these studies was to evaluate the feasibility of purifying Kansas River water by combining coagulation and filtration in one high‐rate process. The method used was similar to the Russian contact clarification process, and coagulants were injected into the raw water immediately ahead of two upflow sand filters, with coagulation and clarification taken place within the filter beds. Studies included investigation of the effects of the rate of filtration and the depth of sand on the operation of the filters, with emphasis on studies of high filtration rates. Alum was used as the coagulant. Addition of a polymer with the alum was also studied. Jar tests were conducted prior to each filter run to determine the minimum alum dosage that would produce a pin point floc.