Municipalities urged to probe energy efficiency solutions for treatment plants

9th August 2013

  

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Municipalities should investigate energy-saving opportunities by conducting energy audits and issues, such as electrical load management during peak demand periods, must be clear and understood by wastewater treatment plant operations staff, says Water Research Commission (WRC) water use and waste management research manager Dr Jo Burgess.

Energy-saving opportunities from demand- side management programmes include reducing energy costs by shifting power consumption from peak to off-peak hours.

Small and seasonal wastewater treatment plants may benefit from such opportunities, but large treatment plants need to consider them carefully, she explains, citing the WRC South African Energy Compendium of Good Practice in Water and Wastewater study.

“Energy savings of up to 50% have been demonstrated by case studies in wastewater processes focused on aeration. Simple changes in control methods and set points have fre-quently shown substantial quick-wins, while checkups on the plant, control methods, operational routines and maintenance have proven worthwhile,” highlights study project leader Dr Marlene van der Merwe-Botha.

Opportunities exist to improve the current wastewater treatment processes by applying new solutions and technologies that can reduce energy inputs or generate energy.

A 2009 WRC survey on the quality and quantity of wastewaters in South Africa identified the top three sectors with the greatest potential for energy recovery as the formal and informal animal husbandry sector, including cows, pigs and chickens; fruit and beverage industries, including distillery, brewery, winery, fruit juicing and canning; and domestic black water, namely sewage.

An estimated 10 000 MWh a year of thermal energy can be recovered from wastewaters in South Africa, which is equivalent to about 7% of Eskom power generation a year.

South Africa has not been actively pursuing and implementing energy-saving projects on a large scale, mainly as a result of electricity that was readily available and cheap. Case studies and operational data are not readily available or data were poorly recorded and not verified.

“The study may need to be developed to guide towards best practice of ‘developmental industry’, as opposed to being a compendium of best practice by way of case study document-ation,” emphasises Burgess.

The WRC commissioned the South African Energy Compendium of Good Practice in Water and Wastewater to provide the South African water and wastewater treatment sectors with an objective and logical evaluation of the current and expected impact and consequences of power outages on water and wastewater treatment services.

The project is supported by the Global Water Research Coalition partners, represented by the four Continental Coordinators in Australasia as Australia and Singapore, Europe, South Africa and the US. Each continental group has produced a report of best examples submitted by utilities in their region. When all four continental reports are available, they will be compiled into a best practice document, titled Energy Efficiency in the Water Industry: A Compendium of Best Practices and Case Studies.

Edited by Martin Zhuwakinyu
Creamer Media Senior Deputy Editor

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