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A Case Study for Wastewater Treatment: Llanelli


 

LOCATION: LLANELLI

SUMMARY

The removal of phosphorous (P) during the sewage treatment process is a crucial area of interest within the water industry. Since April 2015, new legislation states a maximum concentration of 
With a major capital scheme and new P consent in place for Llanelli Wastewater Treatment Works (WWTW), DCWW commissioned a trial with Hydro to assess the electro-coagulation (EC) process and a cost-efficient solution to P removal. In accordance with DCWW's 25 year vision toward chemical-free treatment, the greater benefits and applications of EC were explored.

BACKGROUND 

Phosphorous pollution is a major threat to water streams and the aquatic environment, its presence causes many water quality problems including: loss of aquatic species, loss of livestock, possible lethal effect of algal toxins on drinking water, increased purification costs and decreased recreational and conservation value of an impoundment.

Controlling the discharge from municipal and industrial WWTW is a key factor in preventing eutrophication of surface waters. Generally P removal is largely maintained by chemical precipitation which is expensive and causes up to 40% increase in sludge volume. An alternative is biological treatment however, both methods are outdated and would still need further treatment such as pH correction, thus increasing chemical consumption.
 
There is a requirement to implement cost-effective measures for a safer and more sustainable solution to P removal and its entry into the water course.

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HYDRO'S SOLUTION

At Llanelli various waste streams were evaluated to source the optimum and most efficient treatment solution to remove increasing levels of P and iron. A Hydro 400 unit followed by flash mix and flocculation, with a downstream lamella plate separator for solids-liquid separation were installed on site. Due to impressive P removal rates and the best whole life cost solution, analysis confirmed that treating the Centrifuge Concentrate with high P levels was the most beneficial treatment option. Hydro also has the ability to reduce the unit size to suit a smaller treatment flow in order to further decrease the capital (CAPEX) and operational (OPEX) costs. 
 
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