Microconstituents – what are they and what is Their Fate through Wastewater Treatment

Microconstituents are a group of compounds being evaluated by the Water Environment Federation's (WEF) Community of Practice and other organizations and researchers. Endocrine Disruptor Compounds (EDCs) are a sub-group of Microconstituents that include groups of compounds such as human and veterinary drugs, pesticides and industrial chemicals. Only some of the compounds in these groups are EDCs. EDCs include naturally occurring and synthetic steroid hormones, organohalides, metals, alkylphenols, polynuclear aromatic hydrocarbons, crude oil and plasticizers. These compounds may interfere with hormone processes in both humans and wildlife. EDCs are being detected more in the environment in water, wastewater and biosolids as more studies are done and analytical techniques have progressed. The WEF Microconstituents Community of Practice has developed “Technical Practice Updates” on various topics of Microconstituents including one on wastewater treatment and another in development on water treatment.Microconstituents are a concern and have gotten more attention in recent years based on the following:Better analytical methods are finding Microconstituents in numerous receiving watersFeminized fish discovered in Europe in mid 1990sSteroids are implicated in Europe in late 1990sTreatment studies on POTWs (2002-2003) show POTWs are a collection point and one source to receiving watersUSGS study of 139 streams in 2002 detected pharmaceuticals in 80% of samplesTrend towards water conservation and reuse in both private and public sectors resulting in higher concentrations and potential for Microconstituents in reuse water.More media coverage & public awareness and concerns.A review by the World Health Organization has concluded that low-level environmental exposure to Endocrine Disruptors has not yet been demonstrated to cause harm to human health (Damstra et al., 2002). Uptake of Endocrine Disruptors by humans from treated drinking water is relatively low in comparison to other sources such as food (GWRC, 2003).This paper discusses Microconstituents and what is included. The physical and chemical properties and structures of these Microconstituents and EDC compounds that determine the treatment removal mechanisms and applicable treatment technologies are presented. An approach for evaluating and developing wastewater treatment solutions will be discussed. The approach includes a combination of bench-scale and pilot-scale treatability studies which are used to test treatment processes prior to design and the use of process modeling tools which are used to predict removals through treatment processes. Treatability testing case studies are presented along with actual data on removal through municipal and industrial treatment plants.