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.

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 denitrification(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 ClassⅠ-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 ClassⅠ-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 ECOSUNIDE system with A/A/O,more abundant biofacies,darker and more intense zoogloea,more obvious filamentous bacterium,and clearer flocs 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).