Laserfiche WebLink
<br /> <br />Bay Area Clean Water Agencies | City of San Leandro Final Report | 15 <br />sidestream returned to the headworks). In the case of the SLWPCP, ferric chloride addition ahead of <br />the dewatering is recommended where the precipitated phosphorus will be captured with the cake. <br />Recovery of the total phosphorus sidestream load via struvite precipitation is another option to <br />eliminate the phosphorus recycle stream loads. This process produces a useful byproduct (struvite <br />crystals) that can be sold economically. Chemical addition is typically simpler and easier for plants to <br />implement. Plants are encouraged to evaluate the technical and economic feasibility to implement <br />phosphorus recovery by struvite formation at their plant as an alternative to chemical phosphorus <br />recycle load control. <br />A list of the facility needs for sidestream treatment is provided in Table 5-1. <br />Table 5-1. Sidestream Treatment Facility Needs for Ammonia/TN or TP Load Reduction <br />Ammonia/TN Load Reduction Elements TP Load Reduction Elements <br />Feed Pumping (if necessary) Metal Salt Chemical Feed Facility <br />Feed Flow Equalization -- <br />Pre-Treatment Screens -- <br />Biological Reactor -- <br />Aeration Supply Equipment -- <br />Effluent Pumping (if necessary) -- <br /> <br />Table 5-2 presents the estimated nutrient load reductions based on the sidestream treatment <br />described in Table 5-1. The current and permitted capacity with sidestream treatment uses the <br />additional sampling from July 2015 to determine the effluent levels. <br />Table 5-2. Projected Effluent Annual Average Nutrient Discharge <br />Parameter Units NH4-N (lb N/d) TN (lb N/d) TP (lb P/d) <br />Current Discharge1 lb/d 1,600 1,600 146 <br />Discharge with Sidestream Treatment2 lb/d 1,270 1,300 122 <br />Load Reduction3 lb/d 330 300 24 <br />Load Reduction % 21% 18% 17% <br />Annual Load Reduction lb/yr 119,700 106,400 8,800 <br />1. The loads represent average projected loads discharged to the Bay for the period of analysis (30-yr for sidestream). <br />2. As compared to Current Discharge (Note 1). <br />3. Based on the average annual load reduction over the 30-year project duration. The calculation considers days with no discharge. <br />The estimated capital and O&M costs for the recommended sidestream treatment upgrade are <br />presented in Table 5-3. In addition, the estimated cost per pound of nutrient removed is presented in <br />Table 5-3. These unit costs are estimated based on the cost of the elements needed to reduce <br />ammonia, nitrogen, or phosphorus, respectively.