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{sup}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 μm 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{sup}3, whilst COD fractions associated with the suspended, 1.2-0.22 μm, 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.
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