"Recovering wastewater to reuse it and creating power from organic rich effluent – using anaerobic digestion to produce methane – is no longer a concept but a reality, and is being increasingly viewed as a lucrative business decision," says Grahame Thompson, business development manager for Talbot Green Energy. He encourages food and beverage companies with the correct effluent character to investigate the potential for generating energy and recovering wastewater. Water and energy are among the major contributors to production costs; therefore, becoming more self-sufficient in water and energy has both environmental and financial benefits.
Hitherto, the focus of the food and beverage industry in effluent treatment has generally been limited to reducing their effluent discharge tariffs or, at most, treating effluent to a quality that meets municipal standards. But they have failed to realize the true value of their effluent, says Thompson.
Talbot & Talbot suggests a shift in this thinking. It wants to motivate industries to select appropriate technologies that will enable them to treat wastewater that is fit for reuse and simultaneously convert the organic material to energy.
Firstly, treating wastewater through an anaerobic digestion process results in a substantially-treated effluent. Secondly, the resultant biogas can be used for cogeneration purposes.
One ton of Chemical Oxygen Demand (COD) digested produces the equivalent of 350Nm3 of methane and 0.15MW of power. A typical brewery producing 5Mhl of beer per year will produce an approximate 1MW of electricity, equivalent to roughly 8t of coal (at 25 GJ/t). In a recent project completed in Thailand at a 300t/day starch factory, the energy yield was double that required for the mill’s production.
This kind of project makes a factory completely energy self-sufficient, with the surplus being sold to the grid.
Another example is a distillery producing 100kl per day of ethanol. This project has the potential to produce 11.3MW of power which, if fed to a gas engine, could produce 4.5MW of electricity plus 4.5MW of thermal power. The same distillery in terms of fuel replacement could produce the equivalent of 24.3t/day of HFO or 14.2t/day of coal.
Thompson concedes that potential energy-generating projects only become viable at high COD loading rates or in areas where power and fuel are expensive.
Talbot Green Energy focuses on the African market where the correct effluent exists and the costs of fuel and electricity make such projects viable.
In such wastewater treatment and biogas projects, Thompson suggests partnering with a reliable team from conception to implementation – and into operation of the plants. A thorough understanding and extensive experience in various technologies is imperative.
"There is an entire range of configurations and the ability to select and appropriately apply them is a science in itself. For the exercise to be meaningful and sustainable, it requires a stepwise holistic approach that should begin with a wastewater and energy management plan (WWEMP), which considers all site specific conditions and reduces the risk of effluent plant failure in the long run by establishing water management measures from factory floor to end-of-pipe treatment and beyond."
- Talbot & Talbot has established relationships with investors and technology specialists. It has access to a global base of knowledge, skills, experience and resources made available through its Global Water & Energy Alliance. Reference plants exist and site visits can be arranged to develop an understanding of the value of converting waste organics into green energy. Talbot & Talbot’s core business activity is in the management of industrial wastewater. Its multidisciplinary team and holistic approach achieved through its four integrated businesses, provides industries with turnkey solutions to wastewater management and energy recovery.
Talbot & Talbot: Tel +27-33-346-1444,
email@example.com or firstname.lastname@example.org ; website: www.talbot.co.za