Edcs in Wastewater: What's the Next Step?

Abstract

The fact that many known and suspected endocrine disrupting chemicals (EDCs) are being found at environmentally significant concentrations in the effluent of wastewater treatment plants (WWTPs) is receiving increasing attention in public and regulatory arenas. The public is concerned about the safety of consuming trace amounts of EDCs in drinking water, though the only confirmed negative effects from EDC exposure have involved wildlife health. Ample research opportunity exists for the scientific community on this topic: most EDCs have not been identified and/or studied, analytical methods for many identified EDCs have yet to be developed, and the levels of toxicological significance or impact must be established. Additional work must also be done to determine the potential for (1) interactive toxicological effects in EDC mixtures and (2) the formation of undesirable byproducts through treatment. It is likely that the EPA will not consider regulating EDCs until more research has been completed. Research shows that complete biodegradation of many chemicals of concern can be achieved with adequate SRT and/or HRT in the activated sludge system. When contaminants are persistent or if extremely low effluent concentrations are required, however, higher level removal technology may be needed. Several advanced technologies, such as activated carbon adsorption, ozonation, AOPs, and NF/RO, have successfully removed potential EDCs from water. Most of these technologies, however, are expensive to implement and to operate. Optimization of the activated sludge process could be a less costly option. Issues of by-product formation and EDC additive effects will be important considerations in the design of any treatment strategy. Long-term facility planning should allow for design flexibility to accommodate possible future EDC regulations. Potential treatment strategies can be incorporated into existing layouts, and room should be left for new equipment. Process selection criteria such as space requirements, byproduct issues, and compatibility with existing facilities must be considered. Planning should favor processes and management strategies that will address not only the concern for EDCs, but other water quality goals as well, so that capital expenditures will cover more than the single, somewhat unclear EDC issue. Based on current information, it seems logical that a major focus for EDC and PPCP removal should be at the WWTP. Removal of these pollutants from WWTP effluent may solve much of the apparent endocrine disruption problem in the water environment, in addition to providing a cleaner source for drinking water.

Treatment and Removal Strategies for Estrogens From Wastewater

“…Ozone was not particularly effective at oxidizing iodinated contrast media compounds, and AOP combinations with ozone did not significantly enhance removal rates [136].…”

Distribution and Removal of Nonylphenol Ethoxylates and Nonylphenol from Textile Wastewater—A Comparison of a Cotton and a Synthetic Fiber Factory in Vietnam

“…Accordingly, a major portion of the removal of long-chain NPEOs (with log K ow less than 2.5) occurs via biotransformation [100], whereas removal of NP and short-chain NPEOs (with log K ow greater than 4) is more likely via adsorption onto biomass [101,102]. Factors such as HRT, nitrification, organic loading, SRT, biomass concentration (expressed as MLSS), temperature, and pH have been suggested to be significant for governing those mechanisms [81,[103][104][105]. …”

“…In an activated sludge system designed for endocrine disruption compound (EDC) removal, HRT is a parameter of great importance since a complete degradation can be achieved with an adequate HRT [103,105]. The biotransformation of NPEOs occurs in two steps.…”

“…• The Role of Nitrification It has been indicated that nitrifying conditions may play an important role in NP and short-chain NPEO removal with ASPs [81,104,105,109]. At the same time, NPEOs with longer chain (more ethoxylate groups) are more eager to decompose.…”

“…• Extended SRT as an Essence of Microbial Development and Biomass Quality A complete biotransformation of short-chain NPEOs, as aforementioned, may require a specialized microbial inoculum that could be enriched in an elevated SRT system [81,105,110,141]. According to Cirja et al [81], microbial communities including nitrifying bacteria are able to acclimate and develop at the SRTs of longer than 8 days.…”