Tassal Tasmanian Salmon, an Australian salmon farming company, backed away from plans to dump treated wastewater from salmon pens into...
Company has developed an enhanced membrane bioreactor for wastewater treatment
The Aqua-EMBR system consists of an activated sludge extended aeration biological treatment process and an ultrafiltration (UF) membrane system for the separation of activated sludge from treated effluent. Aqua-EMBR is an external MBR system; the UF membrane is positioned outside the bioreactor tank, rather than submerged in the bioreactor tank or in the downstream membrane tank.
The UF membrane modules are arranged vertically and aerated continuously at the bottom. Mixed liquor is transported via air lift pump action through the module, while the membrane feed/recirculation pump is only used to overcome the hydraulic losses and maintain a relatively constant flow of mixed liquor through the membrane. This innovative design reduces much of the feed pumping energy requirement needed to maintain high crossflow velocity.
Applications for the system include wastewater treatment or reclamation in new industrial and municipal wastewater treatment plants (WWTP) or in existing plants undergoing upgrades.
Aqua-EMBR offers several benefits over submerged MBR systems, which already present advantages over conventional activated sludge systems. Because the system has no membrane tank, it can be built more quickly. Installed as one or more skids on a flat concrete slab, the system eliminates the need for complex civil engineering and lowers the risk for contractors due to construction delays caused by weather conditions, environmental or other local uncertainties.
In addition, the system offers an operator-friendly working environment. Operators do not see, smell or come in contact with the biosludge, nor do they work on top of open membrane tanks where the air could contain harmful aerosols. Should maintenance be required, Aqua-EMBR's membrane modules can be removed or replaced without any contact with the biosludge.
One of the first applications for Aqua-EMBR was treatment of effluent generated from a chemical manufacturing plant where Aquatech successfully commissioned a 50 cu m per day capacity plant. After proper sludge acclimatization, it was possible to reduce chemical oxygen demand (COD) by 85% and consistently achieve a reduction of more than 95% of biochemical oxygen demand (BOD).
"Since environmental regulations are becoming stricter every day, it is sensible to treat wastewaters not only to meet environmental norms for discharge, but also to treat and make the wastewater suitable for reuse as process water in the same industry," said Arun Mittal, director of wastewater treatment applications for Aquatech.