The WEF Sustainable Utilities Task Force presents a resource for utility managers seeking examples of succesful sustainability practices

Energy Sustainability and Nutrient Removal from Municipal Wastewater


The state of energy sustainability in wastewater treatment and especially nutrient removal has improved rapidly with development of new technologies and increased concerns for the environment. The ultimate goal of the wastewater treatment industry could be achieving energy self-sufficiency within a facility. The progress that has been made toward this goal with nutrient removal technologies was investigated and the challenges and opportunities facing our industry are identified in this paper. A benchmark for energy sustainability was recently achieved in Strass, Austria, where the energy usage of 1000 kwh/million gallons (MG) treated was achieved, which was actually less than the energy generated by digester gas, . This paper presents a comparison between the U.S. and Austria of potential energy use and generation, and offer approaches that could lead to similar U.S. success in the future. The selection of technologies and their operation impact the sustainability of facilities in two ways; energy management and carbon management. On energy management, the current U.S. energy usage ranges between 600 and 2,600 kwh/MG treated when operated with internal carbon sources. When carbon is imported, the energy usage increases by approximately 600 kwh/MG treated or more, which needs to be either reduced or supplied from the outside sources. For the purpose of energy generation, key factors include, in-plant generation of volatile fatty acids(VFA), increased biogas yield from both enhanced primary settling with chemical addition and conditioning of feed sludge and co-digestion, where feasible . For the purpose of energy conservation, key factors included ability to operate the swing zone, step feed mode of activated sludge , sidestream treatment of recycle loads, and automation with on-line sensors. A list of challenges and opportunities are suggested for reaching a long term goal of energy self-sufficiency. Source: WEFTEC 2009 Proceedings


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Posted: August 27th, 2010 | Filed under: Waste Water Treatment | Tags: , , | No Comments »

Incorporation of an Intentional Struvite Precipitation Model Into a Whole-plant Process Simulator

West Boise WWTP
Boise, Idaho

An intentional struvite precipitation model is incorporated into a whole-plant process simulator allowing for the quantification of impacts to the overall mass balance and associated phosphorus recovery from a wastewater treatment system. The intentional struvite precipitation model predicts the overall struvite quantities generated (as magnesium ammonium phosphate, MgNH4PO4ยท6H2O) and the associated reduction of phosphorus and ammonia across the reactor. The results are incorporated into the overall wastewater treatment facility (WWTF) mass balance, quantifying the impact intentional struvite precipitation has on the nutrient removal performance of the facility. The use of this model in a whole-plant process simulator allows the direct comparison to other nutrient removal alternatives, providing a basis for the selection of the appropriate treatment process configuration. The incorporation of an intentional struvite precipitation model into a whole-plant simulator proved to be a valuable tool in evaluating a number of treatment configurations to meet total effluent phosphorus goals. This technology was compared to traditional treatment configurations, allowing a quantification of overall plant performance. This tool was part of the evaluation process that ended up recommending the use of an intentional struvite reactor at the West Boise WWTF to help improve total phosphorus removal at the facility. Performance from the simulation shows a significant decrease in effluent total phosphorus with the use of an intentional struvite reactor. The simulation indicates a 77-percent reduction of effluent total phosphorus from the use of EBPR only to that with a system that incorporates intentional struvite precipitation. This, along with the sustainable features of the technology, prompted the recommendation of continuing with the implementation into the design of the WWTF expansion. Source: WEFTEC 2009 Proceedings


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Posted: June 23rd, 2010 | Filed under: Waste Water Treatment | Tags: , | No Comments »