| To construct wastewater treatment plant (WWTP) is the most significant and effective solution for water pollution control. Due to high costs of construction and operation, the progress is restricted heavily in China. And energy consumption is usually the focal issue of WWTP operation. Study on energy consumption and energy efficiency for municipal wastewater treatment processes which began a long time ago has neither made much progress nor received adequate attention in China. So far no agreement has been reached concerning the basic theory, research approaches and frames in the domain.In the dissertation based on essential principles of microbial energy utilization and thermodynamical analysis for organic degradation, water quality index and energy index is coupled, theoretic energy-balancing analytical model and technical index system is established for municipal wastewater treatment processes, and evaluating approach for energy efficiency of WWTPs is brought forward. Directed under the founded system, case study was performed through four WWTPs. A energy-saving scheme for one of them was submitted, by means of full-scale experiment, feasibility and reliability of the scheme was validated. Detailed work and major conclusion is as follows:(1) With the aid of investigation on energy utilization status in representative domestic processes, energy consuming features of common wastewater or sludge treatment processes were summarized and energy requirement level of commonly used facilities and units in treatment plant were analyzed. Relationship was evaluated qualitatively between direct energy consuming cost (mostly electricity cost) and operation cost of the whole plant.(2) Correlative theory of chemical thermodynamics and bio-thermodynamics is integrated in the dissertation, and some research fruits are epitomized on energy transfer during organic metabolism, ATP's coupling function between catabolism and anabolism, etc. Furthermore, thermodynamic model for cell proliferation are narrated and appraised. The author believed that wastewater treatment processes comply with thermodynamic laws; as a result of energy loss, reactions occurring in wastewater treatment reactor system are typically irreversible processes; and approach on energy balancing analysis must be founded on theoretic principle of chemical and biological thermodynamics.(3) In the dissertation concept of pollutants' chemical energy was consummated aswell as its calculation procedure. According to different thermodynamic laws on which definitions are based, pollutants' chemical energy are divided into chemical enthalpy and exergy. In terms of different hierarchy from quantitative change to qualitative change of chemical energy, quantitative relationship was established between pollutant's chemical enthalpy or exergy and conventional water quality indexes (TOC and COD). Then coupling between pollutant's concentration indexes and energy indexes had been realized.: the functional relation for water quality index and chemical enthalpy of organic pollutants in wastewater is as: /zt/,= 13.91kJ/gCOD, viz. each gram of gaugeable COD of pollutants embodies 13.91 kJ chemical enthalpy; Average chemical enthalpy of organism cell is 22.15kJ/gVSS; The functional relation for water quality index and chemical exergy of organic pollutants in wastewater is as: Eç™± -13.825 kJ/gCOD, viz. each gram of gaugeable COD of pollutants embodies 13.825 kJ chemical exergy; Average chemical exergy content of organism cell is 22.605kJ/gVSS.(4) Energy balancing black box model and exergy balancing gray box model for wastewater biological treatment unit were established for the first time in the dissertation, through which expression about exterior energy consumption and interior energy transfer in treatment process were unified. These two approaches of energy analysis combined, performance and energy utilization state of four secondary treatment processes are reviewed, which are often adopted in China at present. Energy(enthalpy) balance can be used to disse...
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