UV TRANSMITTANCE CHARACTERISTICS OF A LOW–QUALITY WASTEWATER

摘要

Pond-treated farm dairy (milking parlor) wastewater quality characteristics relevant to UV disinfection system performance were assessed over a five-month period. Unfiltered UV transmittance values of 0.0 %/cm and suspended solids levels ranging from 135 to 490 g/m 3 were measured in effluent from the main study pond system, and similar characteristics were found in other farm dairy pond effluents. Whilst removal of suspended material in the 1.2-0.22 µ m range substantially decreased UV opacity, UV transmittance values increased to only 0.05-1.1 %/cm following filtration. Significant increases in UV transmittance were obtained after removal of colloidal material, with peak values ranging from 26 to 31 %/cm. Soluble components in the wastewater were subsequently indicated to be responsible for a major proportion of non-filterable UV opacity, with a peak UV transmittance value of 98 %/cm measured following activated carbon adsorption of coagulated and filtered wastewater. COD values associated with a UV transmittance of 60 %/cm were estimated at 26-32 g/m 3 , whilst COD fractions associated with the suspended, 1.2-0.22 µ m, colloidal, and soluble material were 50-54%, 20-21%, 14-19% and 11-14%, respectively. Prospects for on-farm effluent quality improvement are limited, and additional UV technology design considerations will be required in order to obtain useful levels of disinfection performance with this wastewater