Function Study On Investment And Operation Cost For Pollution Control In Printing And Dyeing Wastewaters

Printing and dyeing wastewater pollution, as a major pollutant of textile wastewaters, has become increasingly serious in our country. Study and proper establishment of cost functions for printing and dyeing wastewater treatment plant are the powerful supplementary means and basement to solve the contradiction between economic and environmental benefits.As the wastewater treatment facility construction and operation is a huge investment and complex engineering, factors affecting the function are more complex. Analytic hierarchy was used in this study to determine weight indicators of investment and operation costs for printing and dyeing wastewater treatments. Through the establishment of indicator system, various levels of indicators were judged by 1-9 scale method and the relative weight of each index was calculated by MATLAB, then the consistency between parameter orders was checked. Results showed that the daily wastewater treatment capacity and treatment efficiency were the main influent parameters for investment and operation costs. Thus, these two parameters were as major functions for model establishment.Data collected from the waste water treatment plants around the country were analyzed using statistical method as a base to establish the model and classified according to the National Industrial Classification. A total of 41 groups of effective basic data were obtained, including 29 groups of cotton fabrics and 12 groups of cotton polyester blends for printing and dyeing wasterwaters.Two sets of cost function models were established by the traditional method of least squares linear regression and fuzzy linear regression respectively. The power function C = k₁Q^k₂+k₃Q^k₂ was selected as a model and two parameters,wastewater flow and treatment efficiency, were included to reflect a function relationship with cost during the model establishment by the traditional method of least squares linear regression after analyzing all kinds of cost functions applying at home and abroad. Four optimal parameter values, k₁, k₂, k₃ and k₄, were obtained using least square method. The investment cost function C₁ and operation cost function C₂ were obtained for cotton fabric and cotton polyester blends wastewaters by the software 1^st Opt operation and test. Trough investgating relationships between the cost with wastewater flow and treatment efficiency, we knew that the larger the scale, the higher the cost of per flow when k₂ more than 1, and higher efficient of pollution removal rate was obtained when k₄ more than 1 and k₃ more than 0.The model,Y=x₁A₁+x₂A₂+x₃A₃, was applied in bulding the fuzzy linear regressionmodel process. The investment cost function C₁ and operation cost function C₂ were obtained by MATLAB software calculation for cotton fabrics and cotton polyester blends in printing and dyeing wastewaters. All errors were located within the range±20% through test, indicating the model of establishment to be confident.