| Shenzhen is a fast-growing emerging city, launched in2006in ShenzhenSewer Qingyuan Action from the source specification drainage management, rainand sewage diversion. However, due to the existing village of Shenzhen room orother private farmers and other self-help housing construction caused extensivedrainage facilities chaos, widespread rain and sewage confused, wrongly chaosrow phenomenon; addition, among the ongoing construction of Shenzhen some ofthe illegal construction businessmen indiscriminate discharge garbage, makingShenzhen sewage suspended content over the average annual design concentrationin the last three years, reaching278.30~407.25mg/L, the highest concentration of1902mg/L; BOD annual average concentration of less than150mg/L. Highconcentrations of inorganic to the sewage treatment plant pretreatment unit animpact on the treatment process, equipment and piping adversely affected. Butwith the activated sludge in the process of development, especially the problem ofeutrophication increasing cause for concern, sewage treatment in the effectiveremoval of BOD and SS, but also to remove nitrogen, phosphorus and othernutrients. Low-concentration organic wastewater for Shenzhen circumstancesbiological nitrogen removal process carbon, especially readily biodegradable CODis often not enough. Thus, reducing the primary settling tank retention, so thatorganic matter into the primary settling tank to participate as a metabolic substratesubsequent microbiological and biochemical reactions, you should cancel theprimary settling tank is widely promoted. However, increasing the concentration ofinorganic makes grit chamber can not load the original, the subject ofpre-processing unit through a model experiment to explore the optimal operatingparameters to solve the current problems.Through literature review elect swirl grit chamber and aerated grit chamber asthe main object of study for each of a large number of different operatingparameters of the experimental analysis. This study obtained the followingfindings:(1) Shenzhen wastewater treatment plant influent inorganic suspended solidsconcentration of400~500mg/L, especially in the spring and winter staggering.Influent composed primarily of sand particle size of0.10mm,0.15mm and0.85mm grit, namely of the total amount of28.42%sand,30.56%and15.09%; Othermore uniform particle size distribution were less than10%;(2) Aerated grit chamber swirl removal than grit chamber, the total removal ofsand is higher than12.01%. For a particle size greater than0.15mm high removal rate10.05%, particle size greater than0.20mm high removal rate of9.12%.Aerated grit chamber swirl on the removal rate is higher than the grit chamber, theaverage removal rate was3.88%, while the swirling grit chamber is only2.03%.(3) Grit chamber grit removal cyclone impact factor of primary and secondaryorder is: Residence time> Number of stirring blades slice=Paddle height>Impeller speed; optimal operation conditions: residence time of135s, paddleheight is70mm (paddle height/height ratio is0.10), Number of stirring bladesslice is two, impeller speed32rpm and38rpm.(4) Gas-water ratio for aerated grit chamber water quality impact of COD andBOD removal, maximum COD removal rate of41.58%, BOD removal rate of13.73%maximum. Minimum inflow water BOD/TN than outflow water BOD/TNreduced by11.2%; minimum inflow water BOD/TP than outflow water BOD/TPreduced by14.9%. For retention time aerated grit maximum water removal rate ofCOD22.58%, BOD removal rate maximum14.96%. Minimum inflow waterBOD/TN than outflow water BOD/TN reduced by3.8%; minimum inflow waterBOD/TP than outflow water BOD/TP reduced by19.9%.(5) Aerated grit chamber for large particle size (greater than0.30mm) highergrit removal, and removal from the aeration intensity and impact of HRT. Toimprove the small particle size (less than0.30mm) removal selected gas-waterratio0.20and hydraulic retention time2.4min (prototype duration6min) andunilateral removal under optimal aeration, need external carbon source. |
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