Water Environment Laboratory Solutions

Volume 16, Number October/November 2009 Measure for Measure Is your plant receiving the same polymer in different batches? The overall cost of wastewater solids dewatering, transportation, and beneficial use is highly dependent on the use of an effective conditioning polymer. However, it can be difficult to quantify or monitor the quality of these complex chemical products. This article describes methods for polymer characterization and identification that are suitable for analytical laboratories at medium-

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size to large treatment facilities. These procedures, which include testing for active polymer content, charge density, ionic regain, and viscosity, were developed for the District of Columbia Water and Sewer Authority in Washington, D.C., to quantify the characteristics of different polymer batches and ensure that the polymer being delivered had the same characteristics as the product originally proffered. A procedures manual was developed to be generally usable in any treatment facility with a well-equipped lab. Equipment costs, presented in this article, should be compensated by process savings at such treatment plants.

Carbon Control

A Washington, D.C., area wastewater treatment plant hosted a field trial of a total organic carbon (TOC) analyzer to determine if the unit could detect a breakthrough of supplemental carbon used for denitrification.

Adding supplemental carbon is becoming more widespread as wastewater treatment plants are upgraded for biological nitrogen removal. Chemicals used as supplemental carbon for denitrification include methanol and other short-chain alcohols, glucose and related sugars, acetic acid, glycerin, and glycol. However, if excessive supplemental carbon is added to the end of the biological treatment process, it can easily pass through final clarifiers, particle filters, and disinfection systems into the plant effluent. Such a breakthrough of supplemental carbon could causea violation of the plant’s discharge permit. Feeding excess carbon could continue undetected until the completion of a 5-day biochemical oxygen demand test.

In hopes of determining the suitability of an on-line analyzer that could alert operators to excess supplemental carbon, a field trial of an on-line TOC analyzer was arranged as part of the enhanced nutrient removal upgrade at the Piscataway Wastewater Treatment Plant in Accokeek, Md. The field trial also tested the ruggedness of the device to survive the wastewater treatment plant environment.

NEWS

Oregon Toxics Law Requires Monitoring of ‘Persistent Pollutants’

A 2007 Oregon law requires the state’s 52 largest wastewater treatment plants to monitor their effluent in the future for certain “priority persistent pollutants,” including pharmaceutical compounds, personal care products, pesticides, and other microconstituents. As a result, those WWTPs affected by the law may soon face a complex and potentially costly analytical regime, the results of which will determine to what extent they must seek to reduce certain pollutants in their effluent.

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