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The removal of the potent endocrine-disrupting estrogen hormone, 17α-ethinylestradiol (EE2), in municipal wastewater treatment plant (WWTP) activated sludge (AS) processes can occur through biodegradation by heterotrophic bacteria growing on other organic wastewater substrates. Different kinetic and metabolic substrate utilization conditions created with AS bioselector processes can affect the heterotrophic population composition in AS. The primary goal of this research was to determine if these changes also affect specific EE2 biodegradation kinetics. A series of experiments were conducted with parallel bench-scale AS reactors treating municipal wastewater with estrogens at 100-300 ng/L concentrations to evaluate the effect of bioselector designs on pseudo first-order EE2 biodegradation kinetics normalized to mixed liquor volatile suspended solids (VSS). Kinetic rate coefficient (kb) values for EE2 biodegradation ranged from 5.0 to 18.9 L/g VSS/d at temperatures of 18 °C to 24 °C. EE2 kb values for aerobic biomass growth at low initial food to mass ratio feeding conditions (F/Mf) were 1.4 to 2.2 times greater than that from growth at high initial F/Mf. Anoxic/aerobic and anaerobic/aerobic metabolic bioselector reactors achieving biological nutrient removal had similar EE2 kb values, which were lower than that in aerobic AS reactors with biomass growth at low initial F/Mf. These results provide evidence that population selection with growth at low organic substrate concentrations can lead to improved EE2 biodegradation kinetics in AS treatment.

The aim of this study was to investigate the occurrence and fate of colloidal and dissolved organic nitrogen (CON and DON) across biological nutrient removal (BNR) activated sludge bioreactors. Primary and secondary effluent total nitrogen (TN) measurements and component fractionation, CON and DON concentration profiles across BNR bioreactors, and laboratory batch experiments with the process mixed liquor were carried out at several full-scale BNR plants in northern Poland. The organic nitrogen (ON) components were divided into high CON, low CON, and DON based on sequential filtration through 1.2, 0.45 and 0.1 μm pore-size filters. The average influent DON(0.1 μm) (<0.1 μm) concentrations ranged from 1.1 g N/m(3) to 3.9 g N/m(3) and accounted for only 4-13% of total organic nitrogen. In the effluents, however, this contribution increased to 12-45% (the DON(0.1 μm) concentrations varied in a narrow range of 0.5-1.3 g N/m(3)). Conversions of ON inside the bioreactors were investigated in more detail in two largest plants, i.e. Gdansk (565,000 PE) and Gdynia (516,000 PE). Inside the two studied bioreactors, the largest reductions of the colloidal fraction were found to occur in the anaerobic and anoxic compartments, whereas an increase of DON(0.1 μm) concentrations was observed under aerobic conditions in the last compartment. Batch experiments with the process mixed liquor confirmed that DON(0.1 μm) was explicitly produced in the aerobic phase and significant amounts of ON were converted in the anoxic phase of the experiments., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Two estrogen fate and transformation models were integrated with a comprehensive activated sludge model (ASM) to predict estrogen removal based on biomass and solids production. Model predictions were evaluated against published full-scale plant data as well as results from a laboratory-scale sequencing batch reactor (SBR) fed synthetic wastewater. The estrogen fate model relating the rate of total estrogen degradation to soluble estrogen concentrations successfully predicted estrogen removals when compared with measured concentrations. Model fit 17α-ethinylestradiol (EE2) biodegradation rate constant was 19 to 43% of the estrone (E1) value and 31 to 72% of the 17β-estradiol (E2) value.

The WERF Nutrient Challenge is a multi-year collaborative research initiative established in 2007 to develop and provide current information about wastewater treatment nutrients (specifically nitrogen and phosphorus in wastewater), their characteristics, and bioavailability in aquatic environments to help regulators make informed decisions. The Nutrient Challenge will also provide data on nutrient removal so that treatment facilities can select sustainable, cost-effective methods and technologies to meet permit limits. To meet these goals, the Nutrient Challenge has teamed with a wide array of utilities, agencies, consultants, universities and other researchers and practitioners to collaborate on projects that advance these goals. The Nutrient Challenge is focusing on a different approach to collaborating and leveraging resources (financial and intellectual) on research projects by targeting existing projects and research that correspond with its goals and funding those aspects that the Nutrient Challenge identified as a priority. Because the Nutrient Challenge is focused on collaboration, outreach is an absolutely necessary component of its effectiveness. Through workshops, webinars, a web portal and online compendium, published papers, and conference lectures, the Nutrient Challenge is both presenting important new information, and soliciting new partnerships.

Estrogens from anthropogenic and livestock sources are a serious concern for aquatic ecosystems at concentrations less than 1 ng/L Fundamental process parameters to reduce estrogenic activity were investigated for two biotreatment methods: heterotrophic bacterial degradation in municipal activated sludge (AS) and a nitration process that is applicable to high NH4-N wastewaters. Batch tests with estrogen and nitro-estrogen compounds were conducted at nanogram per liter concentrations with mixed liquor from an AS wastewater treatment facility (WWTF) operating at a 3 day solids retention time (SRT) and a membrane bioreactor (MBR) WWTF operating at a 30-40 day SRT. The estrogenic activities of estrone (E1), 17beta-estradiol (E2), and 17alpha-ethinylestradiol (EE2) were reduced 80-97% following nitration. First-order biological degradation rate coefficients (kb) of the nitrated estrogens were 10-50% lower than the parent estrogen compounds. The kb values for EE2 in MBR and AS mixed liquors were similar, 1.67 and 1.63 L/gVSS-day respectively, indicating that the bacteria responsible for EE2 degradation were present at long and short SRTs. The kb values for E1 and E2 were 2 orders of magnitude greater than for EE2. EE2 degradation was 7.5 times faster in the presence of E1 and E2, and no effect was observed with other estrogen mixtures.

Aceticlastic methanogens are seen as a key to digester capacity and stability. This paper develops and applies an assay to measure digester stability by measuring the maximum aceticlastic methane production rate (Vmax,ac). The Vmax,ac in combination with acetate concentrations was found to be an effective digestion monitoring tool to indicate process upsets. At steady state, thermophilic, first stage and short SRT digesters generally had a greater Vmax,ac than mesophilic, second stage or long SRT digesters. The ratio of the Vmax,ac to the plant aceticlastic methane production rate, termed the Acetate Capacity Number (ACN), is a measure of the excess capacity of the digester. Either Vmax,ac or ACN can be used to estimate the capability to handle higher organic loading rates. Monod modeling was used to predict Vmax,ac, ACN and maximum VS loading rates for mesophilic and thermophilic digestion and for staged digesters to better understand expected digestion capacity and stability.

The abundance and relevance ofAccumulibacter phosphatis (presumed to be polyphosphate-accumulating organisms [PAOs]), Competibacter phosphatis (presumed to be glycogen-accumulating organisms [GAOs]), and tetrad-forming organisms (TFOs) to phosphorus removal performance at six full-scale enhanced biological phosphorus removal (EBPR) wastewater treatment plants were investigated. Coexistence of various levels of candidate PAOs and GAOs were found at these facilities. Accumulibacter were found to be 5 to 20% of the total bacterial population, and Competibacter were 0 to 20% of the total bacteria population. The TFO abundance varied from nondetectable to dominant. Anaerobic phosphorus (P) release to acetate uptake ratios (P(rel)/HAc(up)) obtained from bench tests were correlated positively with the abundance ratio of Accumulibacter/(Competibacter +TFOs) and negatively with the abundance of (Competibacter +TFOs) for all plants except one, suggesting the relevance of these candidate organisms to EBPR processes. However, effluent phosphorus concentration, amount of phosphorus removed, and process stability in an EBPR system were not directly related to high PAO abundance or mutually exclusive with a high GAO fraction. The plant that had the lowest average effluent phosphorus and highest stability rating had the lowest P(rel)/HAc(up) and the most TFOs. Evaluation of full-scale EBPR performance data indicated that low effluent phosphorus concentration and high process stability are positively correlated with the influent readily biodegradable chemical oxygen demand-to-phosphorus ratio. A system-level carbon-distribution-based conceptual model is proposed for capturing the dynamic competition between PAOs and GAOs and their effect on an EBPR process, and the results from this study seem to support the model hypothesis.

This paper reports on the design, implementation, and results of a course focused on decentralized and onsite wastewater treatment in global contexts. Problem-based learning was the primary pedagogical method, with which students tackled real-world problems and designed systems to meet the needs of diverse populations. Both learning and course evaluations demonstrated that the course was successful in fulfilling learning objectives, increasing student design skills, and raising awareness of global applications. Based on this experience a list of recommendations was created for co-developing and team-teaching multidisciplinary design courses. These recommendations include ideas for aligning student and teacher goals, overcoming barriers to effective group-work, and imbedding continuous course assessments., (Copyright IWA Publishing 2008.)

The stability, capacity, and solids destruction efficiency of single versus two-stage anaerobic digestion was studied in bench-scale reactors using combined waste activated and primary sludge. Laboratory staged mesophilic digesters showed an improved volatile solids and volatile suspended solids destruction efficiency over a single-stage system (at the same total solids retention time [SRT]) of approximately 3.2 and 5.8 percentage points, respectively. To quantify stability and capacity, a new digester monitoring method was introduced that measured the digester maximum acetate utilization capacity, V(max,ac), and was used to investigate the potential for digester instability at different transient loadings. The ratio of the V(max,ac) value to the estimated acetate production rate for a given digester loading was termed the acetate capacity number (ACN). Values greater than 1.0 indicate excess acetate utilization capacity. The first stage of the laboratory two-stage mesophilic system (10-day SRT for each stage) had an ACN number of 1.3 compared with a value of 1.8 for the single-stage 20-day SRT digester. Thus, while a staged mesophilic system can improve solids destruction efficiency, it demonstrates a lower capacity for metabolizing highly variable loads.

Recuperative thickening of anaerobic digester sludge (thickening with solids return) yields increased digester capacity. Common thickening methods cause oxygen exposure to the digester sludge. This study evaluated the effects of various levels of oxygen exposure on the acetoclastic methanogens. Gravity belt thickening had no detrimental effect on the acetoclastic activity. From a 7-day batch test with continuous oxygen exposure of digester sludge, a 12% loss in acetoclastic activity was predicted for a digester with a 20-day solids retention time (SRT) and 100% recycle with recuperative thickening via dissolved air flotation thickening. However, a greater loss (27%) was found from a long-term, bench-scale digester operated under similar conditions. This loss did not affect the digester performance, as measured by volatile solids destruction. This research suggests that recuperative thickening may not affect digester performance at a long SRT with constant operation, but may change the reserve capacity of the anaerobic community.