The BER-series is a submersible self-aspiration ejector designed for aeration and mixing of wastewater. It is composed of a combination of submersible pump and venturi-jet based diffuser. The BER-series draws in air and ejects the mixture of air and water through the diffuser. The ejection produces a single but strong mixing current in the water. It is suitable for pre-aeration in sewage and wastewater treatment, mixing to prevent sludge settlement, supplying oxygen in aquaculture, etc.