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Biologically Engineered Single Sludge
Treatment – BESST
Nutrient Removal in Ireland The demand for total nutrient removal is increasing, due to the Water Authorities’ aim to reduce nitrate levels from wastewater. High nitrate levels in wastewater are a serious threat to the environment, and the Water Authorities water abstraction sites. WPL successfully brought to the market, its groundbreaking “Biologically Engineered Single Sludge Treatment” plant (BESST), which can meet even the most stringent of consents. The process which has been developed by WPL, from the “Modified Ludzak-Ettinger” (MLE) process, has been packaged in an innovative, new design which lowers cost and maintenance needs. The Project WPL installed their first BESST plant together with the first nitrate-treating, small scale plant, at the Millbrae Nursing Home, County Tipperary, in Ireland in August 2006. In this case, the Millbrae Nursing Home faced a very strict revised discharge consent, which allowed them to discharge to the River Newport which then tributes to the River Shannon. The Environment section of the County Council provided the stringent discharge consent, of 10:10:5:15:2 (BOD:TSS:NH4-N:TON:TP) as part of the ongoing environmental campaign of pollution prevention. Mr Carew, the owner of the nursing home, was advised by Waste Water Solutions and WPL, that the WPL BESST plant would be the best solution to his problem, as it would be capable of meeting the consent, and had low maintenance costs. The WPL BESST plant uses technology which is purposely designed for nutrient removal, allowing treatment from 100pe to 1500pe. This Plant was particularly beneficial at this site as it was, and still is today, one of very few package wastewater treatment systems available on the market, that is capable of de-nitrification. In addition, very advanced levels of BOD and TSS removal are achieved, due to the integrated Upflow Sludge Blanket Clarifier (USBC), which enables it to meet some of the tightest discharge consents imposed by the Environment Agency, and SEPA. The WPL BESST also achieves good levels of biological phosphorus removal which reduces chemical tertiary polishing, thus reducing running costs associated with chemicals and tankering. Another benefit of the WPL BESST, is that it requires minimal ongoing operator involvement once the unit has been commissioned, which helps reduce continuing operational costs. With longer de-sludging periods and an integral digester, the system will allow for the reduction of associated disposal and treatment costs. Also, the WPL BESST can be installed above or below ground level as per customer requirements. The Achievement Finally, WPL Ltd could guarantee a process that is fully automated, self monitoring and self correcting, using hardwired feedback control systems and in-line instrumentation. This was an important requirement in this case, since the plant would not have an operator on site all the time, and the client was not knowledgeable enough to carry out performance testing and process adjustments himself. After over 18 months of service at the Millbrae Nursing Home, the WPL BESST plant continues to produce excellent results, fully meeting the stringent discharge consent. The plant has only been de-sludged once since its installation, and has been problem free since its handover. The Future For Water Treatment And The WPL Besst There is scope for extended nutrient removal within the UK. Consents are set to increase to more stringent levels, and therefore the demand for this type of plant, (WPL BESST) will continuously grow in the future, as part of continuing to care for the environment. In England, industrial applications are already showing an increased interest. In Scotland and Ireland the demand for plants, such as the WPL BESST, is increasing, as the set discharge consents are more stringent due, to river water quality objectives.
BOD = Biological Oxygen Demand, TSS = Total Suspended Solids , NH4-N =
Ammonium-Nitrogen,
TON = Total Oxidised Nitrogen , TP= Total Phosphorus |
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