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The presence of cationic pollutant metals in municipal wastewater effluent is a concern because stringent discharge requirements cannot always be met with conventional treatment methods. Attempts to improve metal removal are often unsuccessful because a significant fraction of the cationic metals are complexed by the synthetic chelating agent ethylenediamine tetraacetic acid (EDTA).
To identify practical approaches for improving metal removal, an analytical method for measuring metal-EDTA complexes was used to survey metal speciation at a series of wastewater treatment plants. Following these analyses, bench-scale experiments were conducted. The survey data indicated that pollutant metal-EDTA complexes account for a significant fraction of the dissolved metals in wastewater. The bench-scale studies indicated that ferric chloride addition improves the removal of copper and zinc by approximately 20%.
To test the results of the bench-scale experiments, a full-scale experiment was conducted by interrupting chemical addition at a municipal wastewater treatment plant that normally adds ferric chloride during primary treatment. Results indicated that ferric chloride addition had a slight impact on metal speciation but no effect on metals removal. The lack of an effect was attributed to changes in metal speciation that occurred during primary treatment irrespective of ferric chloride addition.
Strategic Risk Communications Process for Biosolids Land Application Programs
The long-term viability and sustainability of biosolids land application is dependent on continuously earning stakeholder confidence, trust and support. This requires ongoing and effective...
Development of a Protocol for Risk Assessment of Microorganisms in Separate Stormwater Systems
Recent research has shown that the concentrations of microbial indicator organisms (e.g., fecal coliforms) in stormwater may be quite high. However, studies have not clearly established...
Greenhouse Nitrogen Emissions from Wastewater Treatment Operation: Phase I
Available as eBook only
Engineered biological nutrient removal (BNR) processes are used mainly to achieve improved water quality. However, BNR strategies could be a...
Assessment of Technology Advancements for Future Energy Reduction
The wastewater industry is continuously seeking new technologies that will reduce the need for purchased energy and improve its ability to beneficially recover resources. In addition, within...
Non-traditional Indicators of System Performance
The use of real-time sensors and supervisory control and data acquisition (SCADA) systems has become commonplace in large centralized wastewater treatment systems. On-line sensors and SCADA...
The Governance of Water Regulators
The establishment of dedicated regulatory bodies in charge of regulating water services, whilst being recent, is nevertheless a consistent trend among OECD and non-OECD countries. This report...
Water Sensitive Cities
Today’s urban water managers are faced with an unprecedented set of issues that call for a different approach to urban water management. These include the urgent changes needed to respond to...
Cryptosporidium Removal, Occurrence, and Inactivation Methods for Wastewater
Treatment of drinking water was once considered sufficient for reducing the risk of infection from pathogenic organisms. However, as our knowledge of established and emerging pathogens in water...