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).

Effect of vacuum degree and aeration rate on sludge dewatering behavior with the aeration-vacuum method

Due to large-scale dredging operations, a large amount of sludge is inevitably produced. Large areas of land are occupied when the dredged sludge is discarded in the disposal site as waste material. The sludge dewatering with aeration-vacuum (SDAV) method is suit for treating the sludge with high water content and high clay content in the disposal site. The water in the sludge can be discharged out. The volume of the sludge can be reduced quickly, and the recycling of the land can be accelerated by this method. Most importantly, this technique is an efficient way to deal with clogging problems when pumping water from high water content, high clay content dredged sludge. Vacuum degree range tests, the aeration rate range tests, and the influencing factors of sludge dewatering behavior tests were conducted with a self-developed SDAV model test device. Sludge samples were taken from the South-to-North Water Diversion East Line Project in Huai’an White-Horse Lake disposal site, Jiangsu Province, China. The optimal range of vacuum degree and aeration rate were obtained through the test results, and the mechanisms for how the two factors work and how they affect the sludge dewatering behavior were analyzed. The suitable vacuum degree range in SDAV is below 50 kPa, and the suitable aeration rate is about 1.0 m3/h. The low-vacuum degree contributes to reduce the ad-sorption effect of micro-channels on soil particles in filter material and to maintain the arch structures. Aeration has the effects of expansion, disturbance, changing Reynolds number, and dynamic sieve separating. The pump quantity of water per meter of filter tube (m) has different change rules as the vacuum degree changes under different aeration rates. The reason is that the formed arch structures’ conformation and permeability differ greatly under different combined-conditions of vacuum degree and aeration rate. The optimal combined-condition for dewatering the sludge is 35 kPa with 1.0 m3/h.