Toasting success of brewery’s energy scheme

Louise Smyth

Skol Brewery Rwanda transforms wastewater into green energy to profitably benefit the African environment

Skol Brewery has upgraded its Rwandan Kigali plant with Global Water Engineering (GWE) waste-to-energy technology that turns wastewater organic pollutants into biogas, or green energy, to profitably power plant boiler equipment while achieving high environmental benefits.

The country has a strong need for sustainable technologies, with the World Health Organisation’s African Regional Office identifying, “Rwanda undoubtedly faces significant environmental challenges, and needs to invest significantly in adapting to current climate challenges as well as in adaptation to future climate change.”

Water shortages are also a big problem in Rwanda, with water needs in Kigali city being only met at 50% or less especially in dry season in a city with urbanisation growth rate of more than 9% annually.

Skol Brewery Rwanda’s new installation, incorporating the efficient and proven GWE waste-to-energy technologies, aligns the brewery with top international environmental wastewater standards and demonstrates the company is taking important action to ensure the sustainability of its operations, says GWE Chairman and CEO Jean Pierre Ombregt.

The new process at the Kigali plant involves GWE’s anaerobic waste digestion technology, which is currently used in more than 150 waste-to-green energy plants worldwide, including dozens of breweries. The technology not only improves sustainability outcomes, but also decreases operating costs.

The anaerobic digestion technology is also integral to approximately 400 high-quality industrial wastewater and waste treatment plants, the benefits of which are applicable to any food and beverage, agribusiness or manufacturing operation with one or more organically loaded wastewater and waste streams.

Skol Kigali’s new continuous system – which replaces an old sequential batch reactor – highly efficiently removes organic waste material from production wastewater, converting more than 90% of the wastewater’s chemical oxygen demand (COD). The new wastewater treatment plant is a reliable method of turning organic waste into usable biogas.

This organic material is transformed into biogas (mainly methane) to replace
the need for an equivalent amount of fossil fuel to power the plant boilers equipment, while the treated wastewater effluent leaving the plant delivers high environmental benefits through achieving discharge limits of 250mg/L COD.

The new process – now successfully in its first full year of operation – begins with pre-treatment, followed by a modern treatment line using GWE’s robust Anubix-B system at the heart of the operation. A sludge management and dewatering unit is also used to process any excess sludge.

“The methane-rich biogas produced by the Anubix process is reused to power an existing boiler unit, replacing baseline power requirements, which is a further benefit to the brewery,” says Ombregt.

“Breweries and other food and beverage companies, are often literally flushing money down the drain in the form of wastewater. They are spending money to treat or dispose of their waste water, when they could be treating it as a resource and turning waste water into a profitable source of energy,” he adds.

The Skol Brewery plant during construction
Because it is a continuous system, green energy can continue to be generated consistently. This base load green energy capacity represents a further major advance on the plant’s previous Sequence Batch Reactor system. The new GWE system handles wastewater inlet quantities of 920m3 per day.

The upgraded plant has a capacity of 3220kg/L of organic matter, or Chemical Oxygen Demand (COD) load. Inlet COD concentration is 3,500mg/L and the COD effluent discharge limit is 250mg/L, with the GWE process removing more than 92% of COD and radically improving the effluent water quality, meaning that Skol Brewery has a minimal impact on local water systems.

“Using this sort of technology to not only treat wastewater and turn it into green energy, but also to power existing boilers or otherwise utilise the additional biogas is becoming increasingly common as forward-thinking companies strive to meet sustainability initiatives and minimise their negative impacts on the environment. Larger anaerobic treatment installations can even generate additional profit in perpetuity, because excess biogas or energy can be sold back to the grid,” says Ombregt.

Developing countries such as Rwanda are highly aware of the need for sustainability, and are increasingly implementing technologies to safeguard the environment and precious natural resources like water.

Although there is still a long way to go – and this applies to everyone, globally – early adopters of environmentally harmonious technologies such as Skol Brewery will pave the way for further advances in energy-efficiency that will benefit communities and the country
as a whole.

Recent Issues