MINLP Wastewater Stabilisation Ponds Synthesis using Rigorous Models under Different Scenarios

HOCH, PATRICIA M.; OCHOA, MARIA PAZ; ESTRADA, VANINA

Computer Aided Chemical Engineering

Elsevier B.V.

Lugar: Amsterdam; Año: 2016 vol. 38 p. 2103 - 2108

1570-7946

In this work, we formulate a network embedding rigorous models for three different typesof stabilisation ponds (aerobic, anaerobic and facultative). The model is formulated as amixed integer non-linear programming (MINLP) problem implemented in GAMS. Theponds are modelled taking into account mass balances for the main groups of bacteria,different types of organic load, algae biomass and nutrients. The objective is to synthesiseand design the wastewater treatment networks (WWTN) that minimises the total annualcosts, including operating and capital costs, subject to maximum allowable concentrationof contaminant on the effluent in order to fulfil environmental regulations. Theoptimisation is performed under different scenarios of inlet concentration of organic loadto take into account process uncertainty. For the base scenario studied, optimalconfiguration consists of a sequence of two aerobic ponds followed by a facultative one(aer-aer-fac), with recycle only in the first pond. System efficiency on COD removal ismore than 65% with a total cost of USD 52,749. Scenarios? analysis shows that resultsstrongly depend on inlet organic load concentration.