Beverage producer and distributor South African Breweries (SAB) Alrode plant has developed a biogas recovery project to reduce dependence on fossil fuels to provide energy for the plant.
The project has two phases, firstly treating the brewery’s wastewater biologically and, secondly using its biogas by-product as an alternative energy source for the boiler.
The biogas recovery project’s first phase primarily treats the brewery’s effluent by converting organic material into methane gas by means of the anaerobic digestion process. The brewery currently produces five-million litres of effluent a day, with an organic load of 25 t/d. The anaer- obic digester converts 90% of the organic load into biogas, which equates to 9 265 Nm3 of biogas produced each day. The biogas has a methane content of 85%.
During the second phase of the project, also referred to as the biogas train, the biogas by-product from the first phase is used to supply fuel to fire a new dedicated biogas boiler, instead of being released into the environment. This fuel switching allows for a decrease in the consumption of 10,4 t/d of coal. “In effect, while we are treating effluent, we are also creating a green energy opportunity,” says environmental engineering company Talbot & Talbot green energy division business development manager Grahame Thompson.
The project holds many associated benefits for the brewery, the environment and the municipality. A tangible financial benefit for the brewery is the decrease in coal consumption, which amounts to a saving of about R7 000 a day, as the methane used as replacement fuel is essentially free. The environment also benefits from the project as the brewery has a reduced dependence on or contribution towards the depletion of a nonrenewable resource. In terms of the municipality, a significant amount of electrical energy and money used to treat the effluent aerobically is saved as the effluent is treated on site at the brewery. Further, there are savings realised on the municipal tariffs.
The project was designed and built by Talbot & Talbot, which specialises in the management of industrial wastewater and the associated beneficiation opportunities. As a result, the company reports that it can recover green energy from industrial wastewater. The biogas train was deliv- ered on a full turnkey basis, under the project management of Talbot & Talbot director and engineering manager Frank Hedley.
SAB’s Alrode plant is a first for the brewery giant in taking steps towards the effective use of the brewery’s effluent and by-products in the generation of a sustainable energy source. As a result, the brewery has been able to drive down production costs and reduce its energy dependence on nonrenewable sources.
Although there are many industries in South Africa that use anaerobic digesters as an effective way to treat their wastewater, SAB’s Alrode plant is the only of its kind to make optimal use of its biogas. The success and benefits of this project should invariably lead to the roll- out to other SAB breweries, reports the company.
Biogas can be used to generate electrical and thermal energy, depending on the breweries’ requirements.
The benefits of fuel switching from fossil fuel and coal to methane, a renewable green energy, are both environmental and financial. This project has roll-out prospects to other breweries within the SAB group.
SAB Alrode plant’s biogas recovery project is a landmark project, particularly in light of increasing international concern over global warming, the exhaustion of nonrenewable resources and escalating energy costs, reports the company.