Effluent Treatment System Improvement via Process Optimization
Authors: Tan S. Chloe , Abdullah R. , Mahmud N. S. , Gadot D. U. 
Published: March 2024

Objectives/Scope

Terminal M, located in Sarawak, Malaysia has been struggling to meet Effluent Discharge Quality (EDQ) post EDQ Improvement Project since 2014 despite operating with chemical injection. The facility is designed with a simple effluent treatment system consisting of skim tank, Induced Gas Floatation (IGF) and holding basin prior to final discharge. Upon improvement project, de-oiler was introduced as a coagulant agent to aid the oil in water separation. However, the operation is still experiencing challenges in meeting effluent quality due to inefficient IGF.

This paper described the collaborative efforts between operations and Centre of Excellence in improving effluent discharge quality via process optimization and subsequently resolving the prolonged pain points experienced by operations in effluent water handling.

Methods, Procedures, Process

Water Practices (WAPs) is a guided document that provides guidance and instructions on produced water treatment operations. It includes setting key performance indicators (KPls) and defining the practices for performance monitoring and control developed in-house. The approach is based on measurements conducted across a four-tiered hierarchy, defining specific elements at each level in the plant operations’ organization. The WAPS approach also includes periodic third-party reviews to assess self-compliance and identify areas of improvement and cost optimization.

WAPS implementation review identified gaps at Induced Gas Floatation (IGF) where the OIW reading at inlet and outlet of IGF was found no or minimal variance. Implementation review team recommended investigation to be conducted to assess the efficiency of IGF. The gaps were further verified with noticeable oily layers on the surface of both holding basin and Effluent Out Fall (EOF), downstream of IGF with stable effluent flow. A hypothesis was made on inadequate chemical mixing due to laminar flow at the injection point upstream of the IGF unit. A field trial was proposed to relocate the de-oiler injection point further upstream at Free Water Knock Out (FWKO) before the control valve to allow better mixing and retention time for the chemical to react with the produced water.

Results, Observations, Conclusions

The field trial shown a significant improvement in OIW reading at IGF outlet, with a 51% OIW improvement from 77ppm to 38ppm while effluent quality at final discharge point has improved from 29ppm to 25ppm, 15% improvement. The trial was conducted for seven (7) scenarios which includes baseline monitoring, relocation of injection point, dosage optimization and combinations of dosage and injection point improvement.

The trial concluded that three (3) key factors affecting quality of effluent discharge are process condition mainly on the volume of produced water received from upstream feeder, secondly location of the injection point and thirdly on dosage of chemical injection. The volume of produced water is directly proportional to dosage changes of chemical injection.

The value creations from this trial are mainly HSE sustenance and cost optimization opportunity which the driver will be implemented to meet company aspiration.

Novel/Additive Information

This collaborative effort has contributed to Effluent Discharge Quality (EDQ) improvement at Terminal M which has been a prolonged pain point from the past. With simple tweaks to the fundamental of process principle, the discharge quality has been successfully improved with none or minimal CAPEX investment.