Wastewater Treatment Optimization for Fish Migration Using Harmony Search

Abstract

Certain types of fish migrate between the sea and fresh water to spawn. In order for them to swim without any breathing problem, river should contain enough oxygen. If fish is passing along the river in municipal area, it needs sufficient dissolved oxygen level which is influenced by dumped amount of wastewater into the river. If existing treatment methods such as settling and biological oxidation are not enough, we have to consider additional treatment methods such as microscreening filtration and nitrification. This study constructed a wastewater treatment optimization model for migratory fish, which considers three costs (filtration cost, nitrification cost, and irrigation cost) and two environmental constraints (minimal dissolved oxygen level and maximal nitrate-nitrogen concentration). Results show that the metaheuristic technique such as harmony search could find good solutions robustly while calculus-based technique such as generalized reduced gradient method was trapped in local optima or even divergent.

Improved Optimization for Wastewater Treatment and Reuse System Using Computational Intelligence

“…Particularly, this study improves existing simulation calculations by exactly finding the critical deficit point of dissolved oxygen sag curve using analytic calculus. While previous approaches [1][2][3] approximate the minimal point by roughly discretizing the continuous river reach into eight points (5,10,15,20,25,30,40, and 50 km away from the effluent spot), this study clearly pinpoints the minimal location by analytically performing the differential calculus. In addition, the proposed formulation considers more practical constraints such as maximal size of irrigated area and minimal amount of filtration treatment.…”

“…For the discharged amount ( 1 + 2 + 3 ) into the river, dissolved oxygen level ( ) at km from the discharge point can be expressed as in (2). Here, is flow velocity (this study uses 7.9 km/day); 2 is reaeration rate (this study uses 0.5/day); is saturation DO (this study uses 8.0 ppm); and are CBOD and NBOD (ppm) at ; and 1 and are rate constants (this study uses 0.35/day and 0.2/day, resp.…”

“…The objective function of the wastewater treatment problem described in the previous section is the total life cycle cost to be minimized as in (17) [1,2]. The cost function consists of three subcosts including filtration process cost ft , nitrification process cost nt , and irrigation process cost ir .…”

“…To date, various simulation-optimization approaches have been proposed to the wastewater treatment problem [1][2][3][4][5][6][7]. However, there is still more room to improve in terms of optimization formulation and simulation calculation for obtaining better solutions.…”

A Novel Hybrid Cuckoo Search Algorithm with Global Harmony Search for 0–1 Knapsack Problems

“…Harmony search (HS) 43,68 , as a relatively effective optimization technique, the optimization process is generally handled by three rules: memory consideration, pitch adjustment and random selection. The three key parameters which have a far-reaching effect on the performance of the HS are harmony memory consideration rate (HMCR), pitch adjustment rate (PAR), and distance bandwidth (bw).…”