Design of wastewater treatment networks with single contaminant

This paper presents new design procedures for the treatment systems with a single contaminant. For the systems with one treatment process, a simple procedure is proposed to determine the pinch stream. Then design of the systems can be obtained easily based on the pinch stream identified. For the systems with two treatment processes, the performing sequence is determined by the inlet concentration constraints of the treatment processes first. Then an initial structure is established, in which all streams are treated by the first process. The treatment network can be obtained by optimizing the treatment amounts of the processes. It is found that for some systems, when the cost ratio of the treatment processes changes, the optimal system structure changes as well.

► A procedure is proposed to determine pinch stream for a system of one treatment unit.
► Design of system with one treatment unit can be obtained based on pinch stream.
► A two-step procedure is proposed to design the systems with two treatment units.
► Final network is obtained by optimizing treatment amounts in the structure.
► Optimal system structure may change when cost ratios of treatment units change.