Academic Study on the Technology Based on Sludge Concentration Subarea

Sludge concentration subarea(A area and B area) is realized by mesh filter unit,solving the higher sludge concentration process problem of MBR system under zero excess sludge discharge conditions.Mass balance of the system is processed,and variety disciplinarians of VSS of A area and B area are analyzed.The results show that XA decreases while HRTA increases.XB decreases while R increases,and ascends as VSS(XA,B) of mesh effluent increases.When XB is a fixed value,XA,B increases as R does and XA decreases slowly while R increases,which theoretically proves the feasibility of the technique.

Sludge concentration dynamic distribution and its impact on the performance of UNITANK

UNITANK is a biological wastewater treatment process that combines the advantages of traditional activated sludge process and sequencing batch reactor, which is divided into Tank A, B and C. In this study, the sludge distribution and its impact on performance of UNITANK were carried out in Liede Wastewater Plant （WWTP） of Guangzhou, China. Results showed that there was a strong affiliation between Tank A and B of the system in sludge concentration distribution. The initial sludge concentration in Tank A could present the sludge distribution of the whole system. The sludge distribution was mainly influenced by hydraulic condition. Unsteady sludge distribution had an impact on variations of substrates in reactors, especially in decisive reactor, and this could lead to failure of system. Settler could partially remove substrates such as COD and NO3-N, but there was adventure of sludge deterioration. The rational initial sludge concentration in Tank A should be 4000-6000 mg/L MLSS.

Experimental study and numerical simulation of the sludge concentration in a sedimentation tank

Sedimentation tanks and clarifiers play a significant role in an active sludge system, and the efficiency of the whole system is closely related with the design and operation of the sedimentation tanks. This paper focuses on the sludge concentration in each cross-section of the sedimentation tank. We measured the sludge concentration to explore its distribution inside the tank, carried in-situ tests to research the fluid pattern and real operational rules of the sedimentation tank. We also used the computational fluid dynamics (CFD) software, PHOENICS 3.5, to simulate the solid-liquid two-phase fluid inside the tank and describe the sludge concentration distribution. The numerical results indicate obviously a sludge-water interface and a compression interface inside the sedimentation tank, a stratified sedimentary region with uniform concentration and a compression region with high concentration at the bottom of the tank. Although the simulated concentrations deviated slightly from those of in-situ tests, they were still acceptable for identifying the sludge interfaces and fluid pattern inside a sedimentation tank, which are important parameters for optimizing the tank size and improving the settling efficiency.

Practice of High Concentration Sludge for Efficient Nutrient Removal from Municipal Sewage

ECOSUNIDE is a new activated sludge process based on the sludge concentration optimization theory.With it,we carried out a high sludge concentration by changing influent mode and distributing carbon source in a reasonable way,which can improve the ecological superiority of nitrification and denitrification for the growth of phosphorous accumulating organisms(PAOs)and nitrifiers and raised the nutrient removal efficiency of municipal sewage treatment plants.In 2007,we adopted this technique in Linyi Sewage Treatment Plant in Shandong Province,China.After the reconstruction,we achieved the high efficiency of nutrient removal with low investment under the dynamic load of the secondary sewage treatment plant.The effluent water qualities meet the classⅠ-A criteria specified in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(GB 18918-2002)and the rest effluent indexes meet the classⅠ-B criteria.Besides,we have above 20% operating cost cut by stopping the internal reflux without power charge increased and any new pool structures built.

Suction characteristics of a thick material pump at high concentrations of coal slime

A test system was designed to study the parameters affecting the volumetric efficiency of a thick-material pump for coal slime.The parameters studied included solid concentration,the slenderness ratio of the suction cylinder and the running speed of the hydraulic cylinder.In the experiment the concentrations of coal slime were 75.7%,76.3%,74.4%,73.5%,72.1%and 70.63%;the running speeds were 0.23,0.18,0.13,0.10 and 0.08 m/s;and the slenderness ratios of the suction cylinder were 1.63,2.26,2.88,3.50,4.13,4.78 and 5.38.The results show that the suction volumetric efficiency decreases gradually with an increase in material concentration.The critical concentration value is 72%;below 72%the suction volumetric efficiency is above 90%,otherwise it decreases rapidly.When the solid concentration reaches 76.3%,the suction volumetric efficiency is only 40%.When the running speed of the piston is less than or equal to 0.23 m/s,the suction volumetric efficiency increases with an increase in running speed.

The Unified Dynamic Theory and Its Engineering Research

The unified dynamic theory reveals the substrate-based nonlinear growth phenomena. It means that the environment of high organism concentration and low substrate state is useful for the growth of weak floras. With ecological superior nitrification denltrification （ ECOSUNIDE ） technology, high sludge concentration by distributing influent to anaerobic and anoxic zones is carried out, and the ecological superiorities of nitrifiers, denitrifiers, and phosphate accumulating organisms （PAOs） get to be promoted. One of the anaerobic/anoxic/oxic（A/A/O） treatment lines of a sewage treatment plant with ECOSUNIDE technology for further investigation on the nutrient removal efficiency is reformed. The advantages of ECOSUNIDE, such as high efficiency and saving energy, are well demonstrated, even under the condition of low temperature （about 15℃） and carbon-resource （C/N ratio lower than 2. 5 ）. In ECOSUNIDE system, the effluent indexes as biochemical oxygen demand （BOD）, chemical oxygen demand （COD）, and NH3--N reach the Class I-A criteria specified in Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant （ GB18918-2002 ）, and suspended substance （ SS ）, total nitrogen （TN）, and total phosphorus（TP） meet the Class I -B criteria. While the effluent qualities of A/A/O system only reach the secondary discharge standard. Through the comparison on the sludge character of ECOSUNH）E system with A/A/O, more abundant biofacies, darker and more intense zoogloea, more obvious filamentous bacterium, and clearer floes edges in ECOSUNIDE system are found.

Simultaneous nitrogen and phosphorus removal under low dissolved oxygen conditions

A full-scale test was operated by using low dissolved oxygen activated sludge process to enhance biological nitrogen and phosphorus removal. When the influent concentrations of CODCr, TN and TP varied in a range of 352.9 mg/L-1338.2 mg/L, 34.4 mg/L-96.3 mg/L, and 2.21 mg/L-24.0 mg/L, the average removal efficiencies were 94.9%, 86.7% and 93.0%, respectively. During the test period of two months, effluent meas of CODCr,, BOD5, NH3-N, TN and TP were below 50 mg/L, 25 mg/L, 10 mg/L and 1.0 mg/L respectively. The low dissolved oxygen activated sludge process has a simple flow sheet, fewer facilities and high N and P removal efficiency. It is very convenient to retrofit the conventional activated sludge process with the above process.

Nitrogen and phosphorus removal under intermittent aeration conditions

A practice wastewater treatment plant was operated using intermittent aeration activated sludge process to enhance biological nitrogen and phosphorus removal. When the influent concentrations of COD Cr , BOD 5, TN, TP, NH 3\|N, TKN, and SS varied in a range of 207.5—1640 mg/L, 61.8—637 mg/L, 28.5—75.6 mg/L, 4.38—20.2 mg/L, 13.6—31.9 mg/L, 28.5—75.6 mg/L, and 111—1208 mg/L, the effluent means were less than 50 mg/L, 20 mg/L, 5 mg/L, 1.0 mg/L, 5 mg/L, 10 mg/L, and 20 mg/L, respectively. Based on a long time of operating results, this process is very suitable for nutrient biological removal for treating the municipal wastewater those water characteristics are similar as that of the Songjiang Municipal Waste Water Treatment Plant(SJMWTP).