If effluent is stored on single or multiple stage ponds before becoming effluent, yes aquatic plants and bacteria may enter into remediation.  Sometimes aeration is needed.   Depending on pollutants, irrigating effluents for soil remediation might be considered.  The specific plants, bacteria, measures should be designed to work in your area.  Avoid use of invasive species that when released in effluent or their seed becomes windblown or transported by biota may become even larger issues.  Native species common to your area are best, as are consults with wildlife, ecology and aquatic specialists if trying out new techniques.

 Dear Prof Hansen, Kakuri stream water is the intended water to remediate. The effluent from Nigeria Brewery Plc is the source of pollution

Do remediation means the river quality and eco-system has already been polluted or destroyed. As I know, it is not inhibited in China to added bacteria to the target water bodies directly, and both bacteria addition and aquatic plants could be used in the project. However, in your case, the needed amount of bacteria is a lot for a river, and maybe not economic feasible.  

Dear Prof W., Wang, I sincerely appreciate your answer.