Reducing energy costs is rapidly becoming a major priority for water and wastewater utilities. As a result, many water and wastewater utilities are performing energy management audits and evaluations to identify energy saving opportunities that will provide energy benefits at the lowest possible capital cost. Many water and wastewater facilities can realize "zero or low cost" energy saving opportunities through managing their energy demand in coordination with the energy billing rates. This is especially true for facilities whose electric energy rate structures include demand ratcheting and time of use billing. In order for demand management strategies to be effective, the demand management strategy must not have any negative impacts to the treatment process and must be coordinated with the energy billing rate structure(s). This paper will present multiple demand management strategies that were identified from multiple energy management audits performed for multiple wastewater treatment facilities. The results of multiple demand management case studies will be presented with an emphasis on demand management strategies that provided a payback period of 1 year or less . Specifically this paper will include the following as a minimum:• A description of common electric utility rate schedules (i.e. Time of Use, Demand Ratchets) and how different rate schedules impact the demand management strategies for water and wastewater treatment facilities. • Typical demand management practices commonly used by water and wastewater utilities including flow equalization, peak shaving, and operations management. • The role power monitoring capabilities has on the demand management capabilities.• The results of multiple case studies where demand management opportunities were identified as a part of an energy management project. KEYWORDSEnergy management, demand management, combined heat and power, biogas utilization, electric utility rates 1705 WEFTEC 2013

Two parallel trains of completely mixed anaerobic fermenters, 300 gal, coupled with gravity thickeners, 90 gal, were operated to ferment primary solids (PS) and grease trap waste (GTW) from the Nansemond Treatment Plant in Suffolk, Virginia. A control treatment train was fed only primary solids at a targeted organic loading rate of 10kg COD/m 3 /d while the experimental train was fed an elevated lipid load, an additional 20% COD load as grease trap waste (GTW), collected from the grease trap waste stream being disposed of at the treatment facility. The desired effluent product was a low solids, high readily biodegradable COD (rbCOD) and volatile fatty acids (VFA) stream that could be used for biological nutrient removal. At present the primary sludge has been found to have a particulate COD to soluble COD (sCOD) conversion rate of 6 to 15%. However, the amount of effluent sCOD contributed by VFAs (C2:C6) ranges from 25 to 80% depending on reactor operational parameters, while the contribution of acetic acid ranges from 20% to 40%. The incremental degradation of the added lipid load was also far below desired expectations at only 6 to 8%. Modifications are required to effectively transform the grease trap waste in a low pH, 5.2-5.5, anaerobic fermenter.

Wet desulfurization is dominant in China’s coal power industry as flue gas discharged from wet desulfurization is over-saturated, includes lots of moisture, and can bring huge interference to the measurement of SO2. When using existing SO2 measuring methods, especially wet desulfurization technology aiming at ultra-low emissions, it is necessary to take into account the impact of water in flue gas. The pH value of condensate water of flue gas after desulfurization with limestone gypsum wet desulfurization is 2, lower than that of desulfurizing slurry, indicating that some SO2 has been dissolved in the water carried by flue gas after desulfurization. In order to avoid the interference of water, infrared online continuous emission monitoring system (CEMS) is equipped with a water removal device. When a conventional condensate water removal method is applied, condensate water will dissolve SO2 and then lead to the relatively low concentration of SO2 in the flue gas measured. When a proper water removal method is adopted, it can effectively avoid the measuring error as a result of SO2 dissolved in condensate water.

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Grease trap waste (GTW) is the fat, oil, grease, and food particle containing wastewater that is removed from food service establishment grease abatement devices. GTW is ubiquitous, has high volatile solids (VS) content, high chemical oxygen demand (COD) content, and relatively low nutrient content. Consequently GTW has received a lot of publicity for its ability to increase anaerobic digester gas production when co-digested with municipal sewage sludge. However, these same characteristics (high COD and low nutrient content) also make GTW a candidate for fermentation to produce readily-biodegradable COD (rbCOD) like volatile fatty acids (VFAs) for use as a carbon source for denitrification.