EVALUATION OF ON-LINE ANALYSIS OF AMMONIA, NITRATE AND ORTHOPHOSPHATE AT BLUE PLAINS WASTEWATER TREATMENT PLANT

摘要

Nitrification, denitrification and phosphorous removal processes are increasinglyrncommon in the Chesapeake Bay region. The Blue Plains WWTP consists of arnseparate stage nitrification and post-denitrification process, and multi-point chemicalrnaddition for phosphorus removal. Nitrification requires aeration and alkalinity to convertrnammonia to nitrate. Post-denitrification requires methanol as an external carbon sourcernto convert nitrate to nitrogen gas. Phosphorous removal is achieved using iron salts.rnThe addition of air and alkalinity to achieve nitrification and methanol to achieverndenitrification can considerably increase operating costs. To accurately quantify thernammonia, nitrate and ortho-phosphate loadings to the activated sludge process, diurnalrnfluctuations in the process flow and concentrations may require analysis, andrnfluctuations during wet weather flow may need to be evaluated. On-line analysis canrnimprove process control at considerable cost savings. The concentration of nitrate,rnammonia and ortho-phosphate were evaluated full-scale for two analyzers. Thernaccuracy of the analyzers was evaluated against laboratory analyses of nitrate,rnammonia and ortho-phosphate using grab samples. These analyzers are varied withrnrespect to their filtration system, flow requirement, detection method, detection limits,rnflexibility and cost. The objectives of this study were to conduct testing of current onrnline analysis technologies to evaluate the potential implementation of on-line analyzersrnfor improved nutrient removal, specifically nitrification/ denitrification and phosphorusrnremoval; to estimate the efficacy of flow paced chemical addition versus load basedrnchemical application for cost savings; to assess the ability of on-line instrumentationrnto consistently provide reliable outputs, such that the concentrations obtained could bernintroduced into a programmable interface; to obtain a better understanding ofrnwastewater treatment plant flow and concentration fluctuations during dry and wetrnweather conditions. On-line instrumentation can save costs and streamline operationsrnat municipal plants. The potential benefits of on-line analysis are described in thisrnstudy.