Effect Of Pre-denitrification Tank Water Distribution Ratio On Nitrogen And Phosphorus Removal In Johannesburg Process And Analysis On Process Control

A2/O process of urban sewage treatment plant is the most widely used tosynchronize biological nutrient removal processes. In this process, a number ofbiological nitrification, denitrification, phosphorus release and uptake reactions such assludge in the same system, and different biochemical reactions and the controlparameters of the matrix there are various contradictory relationship, so A2/O sewagedisposal system is difficult to simultaneously achieve high efficiency of nitrogen andphosphorus removal. This article is based on the actual operation of the traditionalA2/O process on the basis of the test system. Referring to Johannesburg craft oftraditional A2/O process improvements in the test system. And discusses the A2/Oprocess (Johannesburg process) improved pre-anoxic tank with different effects thanthe pre-anoxic water denitrification and nutrient removal systems, with the aim todetermine the optimum water distribution at a fixed operating parameters ratio. Inaddition, on-line monitoring system based on A2/O process pilot systems PLCtechnology are introduced, and the analysis of data on-line process control. The mainresults are as follows.（1）Nitrate that is by the pool return sludge into the anaerobic phosphorusremoval process is the most important factor.（2）Both the A2/O system, or improvements to the Johannesburg process,fluctuations in water quality, changes in the external environment (temperature) for theremoval of COD will not have a big impact on the COD has a relatively stable and efficient removal. Temperature great influence on nitrogen removal. When the mixturetemperature was14.76℃and continued to decline, the ammonia oxidation rate (AUR)and nitrite oxidation rate (NUR) a sharp decline, were reduced from8.27mg/gMLSS·hand6.49mg/gMLSS·h2.42mg/gMLSS·h and1.7mg/gMLSS·h, nitrification process isinhibited, a significant increase effluent ammonia nitrogen removal rate continued todecline.（3）Best pre-anoxic tank with water A2/O process is improved compared toJohannesburg after the trial process to get the best water distribution ratio of10%.while the phosphate concentrations in anaerobic tank are8.72，19.37，16.1and12.99mg/L. With the water distribution ratio of10%，anaerobic phosphorus releaserate，aerobic phosphorus uptake rate and anoxic phosphorus uptake rates are6.94，3.17and2.12mg/gMLSS h. The maximum concentration of anaerobic tank and themaximum content of phosphorus in residual sludge may reach19.37mg/L and25.7mgTP/gMLSS. At the same time effluent COD，NH3-N，TN and TP which canreach the national standard with more than80%probability.（4）PLC technology for process control applications with high sensitivity, easydata acquisition and reliability, easy operation and saves manpower advantages.Through a comprehensive analysis of information on-line monitoring system will pilotthe aerobic tank2#DO set1~1.5mg/L. ORP and extent of anaerobic tank anaerobicphosphorus release rates, the amount of phosphorus release indicative of a good size.According to changes in influent ammonia may be appropriate to reduce the amount ofoxygen, so that the end of the aerobic tank of ammonia concentrations below5mg/Lcan be, both to reduce the nitrogen load, and save operating costs.