Farmers today are faced with an array of products that they can use to improve the fertility of their lands. Organic soil amendments such as biosolids, manures and, to a lesser extent, Municipal Solid Waste (MSW) composts are products that can be used to supplement or replace mineral fertilizers. Many farmers are aware of the benefits that organic products offer, especially in terms of improved crop yields, increased soil fertility, reduced fertilizer costs, and their overall contribution to sustainable agriculture. Concerns have been raised, however, regarding the safety of organic soil...

The purpose of this research project was to examine construction projects that successfully reduced RDII. The research began with a literature review of all published records describing RDII removal projects. Initially, the review identified many projects; however, subsequent evaluation of available information revealed several important realities. First, most RDII removal projects in the country go undocumented. Second, of the RDII removal project summaries that have been published, few provide good data. Third, data gathering and analyses for this report were hampered by lack of...

During wet weather events, separate and combined wastewater collection systems deliver substantial amounts of storm water runoff to wastewater treatment plants. Often these flows inundate collection systems and treatment works creating bypasses of untreated or partially treated wastewater. The federal Clean Water Act (CWA), its amendments, and associated regulations have been attempting to address these concerns for nearly 30 years. These regulations, coupled with the wastewater treatment standards under the CWA, are posing immense challenges to the owner/operators of wastewater systems, who...

Mathematical modeling is a useful tool for the design, analysis and control of wastewater treatment systems. The activated sludge process is one of the most common processes used in wastewater treatment, and therefore is a particularly important candidate for the application of mathematical models. In the 1980s, a task group organized by the International Association on Water Quality (IAWQ) developed a conceptual model of the activated sludge process, which has become an industry-wide standard for the development of computer-based activated sludge models. A recent version of the IAWQ model...

Newport Bay (Orange County, California) is listed by the California State Water Resources Control Board (SWRCB) as a water quality limited receiving water body because of sporadic exceedances of the fecal coliform water quality objectives for body contact recreation. Consistent with federal and state requirements, a Total Maximum Daily Load (TMDL) is being implemented in the watershed. The fecal coliform TMDL in Newport Bay is a phased approach for understanding and controlling the microbiological water quality in the to ensure the reasonable protection of the Bay's beneficial uses. An...

The results of this project should enhance our ability to proactively improve the protection of public health. Equating the presence of pathogens to broad land use categories may help mitigate risks. As millions of dollars are spent on pathogen and storm event monitoring, a better understanding of the pathogen contributions from specific origins will improve watershed management approaches and help mitigate public health risks. This project may also advance sampling procedures needed for effective monitoring, and enhance the ability of wastewater treatment facilities to evaluate priorities...

Under the National Pollution Discharge Elimination System (NPDES), many municipal and industrial wastewater treatment facilities must perform Whole Effluent Toxicity (WET) Testing. Regulatory agencies determine the level of compliance of each facility by making inferences about the results of these tests. There has been some concern regarding appropriate ways to integrate WET tests into NPDES permits. The central issue of this concern involves determining the relationship between WET tests and instream biological conditions. Previous research (WERF project 95-HHE-1) has examined this issue...

Non-potable and potable (principally in-direct potable) water reuse initiatives in the United States have faced increasing public opposition. Several high-profile initiatives have been halted after several years of planning and tremendous expenditures. To understand why the public holds the perceptions they do and what public participation options exist to address water reuse more constructively, a multidisciplinary analysis was undertaken by a team of social scientists, engineers, and water professionals. Through a comprehensive literature review, three in-depth case studies, and a 2-day...

Narrative water quality criteria are an integral component of States' water quality standards but they pose special problems when incorporated into the TMDL process. The TMDL process is typically a quantitative activity, defining numeric allowable loads necessary to meet a numeric water quality objective. Narrative criteria confound development of quantitative TMDLs, due to the absence of these numeric criteria. The objective of this research was to improve the methods for addressing narrative water quality criteria in the TMDL process. The problems associated with narrative criteria in the...

Wastewater disinfection is practiced with the goal of reducing risks of human exposure to pathogenic microorganisms. Ideally, this goal is to be met without introducing other risks, such as those that could be associated with disinfection by-products. The purpose of this research was to assess the effects of wastewater disinfection on human health. This assessment was conducted by examining two fundamental questions regarding the application of disinfection: 1. Should municipal wastewater effluents be disinfected prior to discharge?; and, 2. Under circumstances where disinfection is...