Greener and Cleaner

DESPITE surging energy prices and ever-spreading carbon taxes to counter global warming, many sections of the dairy industry are still pouring potential profit down the drain by overlooking the green energy potential of wastewater. In fact there lies a huge, often hidden, potential in using wastewater as a source of renewable energy, rather than seeing it as a cost.

The industry has tended to treat its wastewater as a cost and place into which production process mistakes are flushed - "If there were spills or if a production product was out of specification, it would be flushed down the drain into the wastewater - that's where the mistakes go," says Mike Bambridge, managing director of CST Wastewater Solutions.

"Such outdated approaches have resulted in bigger and bigger lagoons that are both ground water hazards and big consumers of expensive energy and fossil fuel because of the large energy-intensive aeration systems needed to treat their contents. They also create a lot of sludge and disposal problems," adds Mr Bambridge, a wastewater and green energy specialist whose company has more than 20 years experience in Australasia and which represents the clean water and green energy technologies of Global Water Engineering (GWE).

GWE has successfully built more than 250 plants producing biogas as part of the industrial effluent clean-up system, of which more than 75 were supplied with subsequent biogas utilisation systems for clients worldwide. GWE technologies are being used in global concerns such as Nestlé, Danone, Kraft, National Starch & Chemicals, and Corn Products International, amongst others.

Many of the latest installations use advanced technologies - including anaerobic pre-treatment of water and aerobic polishing - to enhance water discharge purities whilst converting waste to methane to be burned to power boiler and hot water systems, for example, or to power generators and permanently replace fossil fuels.  On average the removal efficiency of GWE's anaerobic wastewater treatment installations is as high as 90-95 per cent, easily bringing the organic load down to regulatory discharge standards for most types of wastewater.

Green energy as revenue generators

GWE CEO Mr Jean Pierre Ombregt says the concept of using wastewater to create green energy is much more widely applicable than often realised.  "Any factory with a biological waste stream or wastewater with high COD (Chemical Oxygen Demand) can easily use this model to generate energy - particularly the dairy industry, for which GWE technologies such as its Flotamet? system combined with its proprietary Dissolved Biogas Flotator (DBF) are specifically designed to take the high levels of fats and oils prevalent in dairy factory effluents," says Mr Ombregt.

So far, most industries have mainly been focusing on treating their effluent to meet local discharge standards.  By doing so, wastewater treatment installations have only generated additional costs and have never been seen as revenue generators.

Instead of looking at efficiency, and getting the inputs and outputs optimised, the dairy industry has traditionally employed big systems to cover process mistakes, with big lagoons and the like requiring huge amounts of energy to aerate.

"However, applying anaerobic wastewater treatment sheds a whole different light on the cost structure of wastewater treatment infrastructure.  It can now actually become a substantial additional source of income for many processing plants," Mr Bambridge explains.

Anaerobic treatment for dairy wastewater

Dairy wastewater is well suited for anaerobic treatment, followed by an aerobic polishNike React Element