Technical Q&A: A beginner's guide to water treatment knowledge

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This post was last edited by hesonchang214 on 2009-8-13 at 19:48. A beginner’s guide to water treatment knowledge – helping newcomers understand aspects related to wastewater treatment as quickly and accurately as possible. 1. What are the main process classifications of the activated sludge method? Answer: Conventional activated sludge process (traditional, nitrification, A/O nitrogen removal, A/O phosphorus removal, A2/O simultaneous nitrogen and phosphorus removal, AB process); Oxidation ditches (Carrousel, double ditch, triple ditch, Oberle, integrated oxidation ditch); SBR (traditional SBR, ICEAS, CAST, DAT-IAT, UNITANK); Contact oxidation process (biological rotating disk?) ) Anaerobic (UASB, hydrolysis-acidification); 2. Conventional activated sludge process? Answer: There’s not much to say. It was already explained in one of the introductory posts; here I’ll mention the points to keep in mind during design. ⑴ The sludge age is short, the residence time is limited, and the aeration tank has poor buffering capacity, so the design flow rate should be calculated based on the maximum daily flow rate. ⑵The rate of biochemical reactions changes with water temperature. High water temperature results in a fast reaction rate and a shorter required retention time for the sludge ； At low water temperatures, the reaction rate decreases, and a longer retention time in the sludge is required. ⑶The oxygen demand varies with water temperature; as the temperature rises, the oxygen demand increases. In design, calculations are carried out based on the average water temperature during the hottest month, which represents the most unfavorable condition. ⑷The air volume of the blower must take into account the effect of elevation. 3. Nitration process? Why is this process needed? Answer: In modern wastewater treatment, only ammonia nitrogen levels are required, and total nitrogen levels are not; in other words, a process that involves only nitrification without denitrification is feasible. Nitrification requires alkalinity! Key design considerations: (1) The nitrification process features a long sludge age and long hydraulic retention time; therefore, the design flow rate is calculated based on the maximum daily flow rate. ⑵The oxygen demand is calculated based on the average water temperature of the hottest month. ⑶Alkalinity needs to be measured; if it is insufficient, alkali must be added or denitrification measures taken. ⑷If the wastewater is of a quality prone to sludge bulking, a biological selection tank can be installed at the inlet of the biological reactor to inhibit the growth of filamental bacteria. 4. A/O denitrification process? Answer: Denitrification, in simple terms, is just denitrification; nitrate is converted into N2 through denitrification, thereby being removed. Denitrification requires an anaerobic environment (DO