Dairy washwater treatment using a horizontal flow biofilm system.
In Ireland, land-spreading is the most widely used method for treating dairy wastewaters. This can be labour intensive and can cause, in some cases, nitrate contamination of groundwater. In this study a simple pilot-scale horizontal flow biofilm reactor (HFBR) with a step-feed was developed and tested at a dairy farm site in County Offaly, Ireland for partial remediation of this soiled water prior to landspreading.During the 122-day study, the top surface plan area (TSPA) hydraulic loading rate was 50 L/m2/day. Influent concentrations averaged: 2904.2 mg total chemical oxygen demand (COD)/L, 950 mg 5-day biochemical oxygen demand (BOD5)/L and 177.9 mg total nitrogen (TN)/L. Between Days 1 and 45 frequent ambient temperatures below 4 degrees C inhibited the build-up of biomass resulting in low removals. From Day 45 the HFBR unit removed 74.9% total COD and 69.6% BOD5, equivalent to TSPA removals of 108.8 g COD/m2/day and 33.1 g BOD5/m2/day. On Sheet 29, by the end of the study, the NH4-N had reduced from 123.1 mg/L in the influent to 37.0 mg/L. TN removal in the reactor averaged 56.0% equating to a TSPA removal rate of 5.0 g TN/m2/day.The HFBR does not require any mechanical aeration, was simple and inexpensive to construct and can provide a robust and economical alternative for the remediation of agricultural soiled water before landspreading.
Clifford
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Department of Civil Engineering, National University of Ireland, Galway, Ireland. eoghan.clifford@nuigalway.ie
Rodgers
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D018441:Biofilms; D002244:Carbon / Q000302:isolation & purification; D003612:Dairying; D007220:Industrial Waste; D007494:Ireland; D009584:Nitrogen / Q000302:isolation & purification; D010100:Oxygen / Q000032:analysis; D014873:Water Pollutants
D007220:Industrial Waste; D014873:Water Pollutants; D002244:Carbon; D009584:Nitrogen; D010100:Oxygen