Project Briefing:

AES Arabia was awarded a contract by the Spanish EPC contractor TecnicasReunidas to supply a wastewater treatment plant for Petrokemya Acrylonitrile Butadiene Styrene polymer (ABS) Project located in Al-Jubail Industrial City, Kingdom of Saudi Arabia. The petrochemical plant is the largest ABS emulsion producing plant in the world with 140,000 Metric tons per year. The raw materials used in the plant are Styrene (SM), Ethyl Benzene (EB), Butadiene (BD), Acrylonitrile (ACN), and Methyl Methacrylate (MMA). The ABS emulsion product shall be of Molding/ Extrusion/ Pipe commercial grades.

The plant will treat several wastewater streams collected from all over the plant, for a total combined flow of 2,400 m³/day.

 Client Requirements:

PETROKEMYA wanted to treat wastewater for the ABS process:

Flow rate: 100 m³/hr

TDS: 2,500 ppm

pH: 1 – 2

COD: 2,000 ppm

TSS: 1,000 ppm

So it can be reused in the plant with requirements to be:

Flow rate: 100 m³/hr

TDS: < 110 ppm

pH: 8.5

COD: < 30 ppm

TSS: < 1 ppm

The reject water is to be disposed to the sea with COD levels of less than: 75 ppm

 AES Solution:

AES provided a solution that will ensure reduction of contaminants while offering redundancies due to the critical nature of the project.

First, water is neutralized by the addition of acid. Then large particles are removed with a self cleaning filter. Equalization tank is provided to regulate the incoming flow to the plant. The equalization tank is provided with aeration system to mix the waste and keep it in aerobic condition.

pH is raised by caustic, so all hardness and heavy metals are removed.

Hydrogen peroxide is added at high pH to create hydroxyl radicals, this will break down hard COD so it can be digested by biological process. Chemically treated water is then processed by MBR and biological process, and treated water is sent for oxidation by ozone for polishing. Water is then softened and passed to double stage RO plant with seawater membranes. Permeate water from RO is sent to plant for reuse as process water and reject is sent to sea for disposal.

 Conclusion and Results:

Since day one, the plant was operated as planned, with high performance.

Initially there was one stream from client process that contained latex material. The latex clogged the self cleaning filter and heat exchangers. This material is considered off-specs as plant was not designed to handle it. It was a minor stream, so client isolated this source and the plant run perfectly after that.

Results after treatment:

TDS: < 10 ppm

pH: 8.5

COD: < 10 ppm

TSS: 0 ppm