Turbine for re-generation of inlet pumping energywastewater

ABD has developed a wastewater process based on expanded bed biofilm reactor technology, which results in a reactor that is about 6 m tall. We are interested in re-generating electricity from the process effluent flow, which is 20-60 m3/h for our standard package plant. Does anyone have the technology to do this? If so, can we discuss capital cost and payback period? Thanks, Mike