Ultraviolet Disinfection of a Secondary Wastewater Treatment Plant Effluent

摘要

Ultraviolet disinfection of a full-scale secondary effluent was investigated during a 13-month field study at Waldwick, New Jersey. The experimental program was designed to demonstrate the feasibility of achieving a fecal coliform density of 200 MPN/100 ml by ultraviolet irradiation; to determine the efficiency of ultraviolet disinfection relative to dosage, power consumption, and effluent water quality; and to assess the utility of the full-scale unit relative to O&M requirements. The impact of photoreactivation was investigated during the field program. Uniform procedures for the calculation of dose and the sizing of ultraviolet systems were also developed. Second order dose-response relationships were developed and were found to provide a rational expression of the microbial response to ultraviolet dose. The ultraviolet absorbance coefficient, k (1/cm), was found to be an excellent parameter for use in the dose expression and in the design sizing of U.V. systems. Photoreactivation was observed and was significantly dependent upon temperature. The phenomenon could result in an order of magnitude increase in coliform density at a temperature of 20 degrees C. The process was determined to be very flexible and simple in operation, requiring minimal maintenance. Costs were estimated to range between 1.2 and 0.8 cents/cu m (4.5 and 3.0 cents/1000 gal) for typical secondary treatment plants with flows between 0.044 and 4.4 cu/sec (1 and 100 mgd), respectively.