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The Water Environment Research Foundation (WERF) has conducted a host of studies, summarized here, to help utilities evaluate and solve their nutrient-related problems. By WERF staff E xcessive amounts of nutrients in receiving waters can cause environmental problems such as harmful algal blooms, hypoxia, and fish kills resulting from biomass decay. Current technology is making it easier to detect nitrogen (N) and phosphorus (P) in our waterways down to the smallest amounts. Many watershed protection plans (e.g., Total Maximum Daily Loads [TMDLs]) use total phosphorus (TP) for setting limits because P is one of the two key macro-nutrients (the other is N) that algae need to grow. It is very expensive to research and implement advanced treatment technologies to remove nutrients to very low levels from wastewater effluent. It often requires significant amounts of energy and chemicals, but operators often have very little understanding of whether the results will actually reduce algae growth. WERF has recently completed a series of research projects that can help the water quality community more accurately determine the true impact of various nutrient species and the best ways to manage them. WERF Nutrients Research Because advanced biological nutrient removal (BNR) systems do a thorough job of eliminating most inorganic N and suspended solids, the result is often effluent that is heavy in dissolved organic nitrogen (DON). And while DON can account for upwards of half of the total nitrogen (TN) coming out of these systems, little is known about how much of this is actually contributing to algae growth. Recently completed WERF research, Uptake by Algae of Dissolved Organic Nitrogen from BNR Treatment Plant Effluents (NUTR1R06e), developed a simple and effective method for measuring bioavailable DON, as well as other forms that are not readily taken up by algae. As a first step, researchers developed a process for separating out different forms of N using various resins. This allowed them to isolate the hydrophilic forms of DON, and in these samples researchers saw very little consumption of DON or algal growth, suggesting that they are not actually bioavailable. Knowing which nutrient fractions are really contributing to algal blooms can help tailor treatment towards the real causes. Another of WERF's recently completed research projects sought further fundamental understanding of effluent P chemical species to interpret and improve technologies for P removal to very low limits. This research looked for insights into the removal efficiency and mechanisms of different P fractions through various treatment technologies. Twenty processes were evaluated at 12 water resource recovery facilities (WRRFs). The P composition in the influent and the secondary and tertiary effluents from the processes were characterized using standard methods, as well as sequential chemical extraction for metal-bound P analysis and molecular cutoff for distribution analysis. Wastewater characterization and fingerprinting were also performed to reveal the association of organic P with identifiable effluent organic fractions. Then, changes in P fractions along the treatment train in each WRRF were evaluated and compared to measured concentrations. The results from this study, Phosphorus Fractionation and Removal in Wastewater Treatment: Implications for Minimizing Effluent Phosphorus (NUTR1R06l), suggest that advanced tertiary treatment processes may achieve low effluent TP levels. Technologies and multistage treatments that target the effective elimination of fine and colloidal particulates, as well as non-reactive P fractions will be required. The next team of WERF researchers looked at the effluent from advanced P removal processes at work across the U.S. and measured the bioavailability of P. What they found was that different removal processes produced different P species compositions, and in most cases, more than half of this P was not contributing to algal growth. They also found a strong correlation between total reactive P and bioavailability — meaning measuring for P that reacts to analyte could serve as a quicker, cheaper, and easier way to measure bioavailability. This research, The Bioavailable Phosphorus Fraction in Effluent from Advanced Secondary and Tertiary Treatment (NUTR1R06m), could aid in the development of watershed protection plans, many of which use TP as a benchmark. Plans that identify and more effectively target those P fractions that are actually bioavailable could help avoid unnecessarily high chemical use and reduce operational costs, sludge production, and greenhouse gas emissions. Because many TMDLs use TP for setting limits without considering the possibility that P fractions may differ in bioavailability, when establishing regulations on TP, the results from this study could be helpful in setting limits. Although meeting lower nutrient levels has become a high priority for many facilities, the benefits of reaching these lower limits can sometimes be offset by the negative impacts that it takes to meet them. Achieving lower limits can necessitate excessive chemical additives and require significant amounts of extra pumping, mixing, and aerating, which require huge amounts of energy. WERF's recently completed research, Striking the Balance Between Nutrient Removal in Wastewater Treatment and Sustainability (NUTR1R06n), suggests that a point of diminishing 34 wateronline.com n Water Innovations The True Impact Of Various Nutrient Species And The Best Ways To Manage Them