Conference Papers | 2009 Conference Papers

METHANOL DOSING TRIAL FOR ENHANCED DENITRIFICATION AT LILYDALE STP

Frank Murphy, Process Engineer, Yarra Valley Water

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ABSTRACT

Under EPA Discharge Licenses, Yarra Valley Water discharges STP effluent to stream which eventually flows via the Yarra River to Port Philip Bay. Nutrient loads in streams and in Port Philip Bay are an ongoing issue and methods of reducing these loads are continually being investigated. One method of reducing the nutrient loads in the bay is to decrease the levels of nutrients entering the water networks through upstream discharges. During late summer and autumn 2008 a methanol dosing trial was conducted at Lilydale STP to assess the possibility of using methanol for enhanced denitrification. A total nitrogen limit of 10 mg/L is in place at the plant and under normal operation effluent total nitrogen levels of 4.5 to 7 mg/L are generally achieved. This paper outlines the procedure used to dose the methanol during the trial period, the sampling regime undertaken to compare nutrient levels in dosed with un-dosed effluent and any process impacts or changes observed while methanol was being dosed at the STP. Results of the trial showing a 40% reduction in total nitrogen levels are also detailed in this paper.

KEY WORDS

Denitrification, Methanol, Total Nitrogen, Nitrate, Sand Filter, Solids