Domestic Wastewater Treatment

Domestic wastewater originates from housing estates, hotels, office buildings and municipal sewer networks. It carries a high organic load but no industrial contaminants, and that character makes biological processes the natural choice for domestic wastewater treatment: micro-organisms consume the organic matter as food and, given enough oxygen, bring the water to a dischargeable quality. Three approaches dominate in practice. Extended aeration activated sludge is common in medium-sized plants because it produces little sludge and is simple to operate. MBR (membrane bioreactor) replaces the clarifier with membranes, works in a far smaller footprint and delivers effluent good enough for reuse. SBR systems operate on a time basis in a single reactor, giving flexibility where flow varies through the day. The right choice is not only a matter of technology: population equivalent, daily flow swing, available area and the applicable discharge limit are weighed together. Aeration is the most expensive part of that equation. The blowers that meet oxygen demand in the biological basin account for more than half of a typical plant's electricity consumption. Diffuser selection and grid layout are therefore an operating cost that will be felt far longer than the capital cost of the plant. A correctly designed fine bubble aeration grid delivers the same treatment performance on markedly less energy. We run the whole process under one roof — from engineering through commissioning — and cut energy use measurably through post-startup process optimisation.