The primary step used by industry and domestic wastewater treatment is chemical flocculation/sedimentation which removes the large particles that are suspended in the effluent. However, the waste stream still may contain soluble organic material that may be harmful to the environment. The removal of the biodegradable organic materials may be accomplished through the use of an sludge digestion process.
There are two types of sludge digesting processes:
To achieve the greatest removal of contaminants from the waste stream by the most cost-effective method, the best cultures of bacteria and microorganisms must be selected for use in the digester. This is accomplished through Bioaugmentation.
Another step performed by treatment plants to further purify the wastewater is through the use of membranes to filter out the dissolved solids which remain in the effluent. The common method used for this step is Reverse Osmosis