Apr-2025

Increasing refinery recycled water quality and usage

A refinery ensured a reliable source of recycled water for cooling make-up water by applying a biofilm detection and control programme to its wastewater treatment plant.

Christina Möring, Johan Hutsebaut and Caroline Bird
Solenis

Article Summary

Water scarcity is one of the most pressing global challenges of the 21st century, presenting wide-ranging ramifications for water-intensive industries. The refining and chemical processing industries, cornerstones of global manufacturing and energy production, are among the industries most affected by limited access to fresh water. As the climate continues to change and water resources become increasingly stressed, these industries must grapple with the potential for operational disruptions, increased costs, and stricter environmental regulations.

Water plays an indispensable role in both refining and chemical processing, where it is used for cooling, generating steam, and transporting materials (such as oil, chemicals, and waste) and acts as a solvent in various chemical reactions. Refinery processing, for example, requires large volumes of water for desalinisation, distillation, and hydroprocessing. Similarly, chemical processing relies on water to maintain optimal temperatures in reactors, treat waste products, and ensure equipment integrity. Therefore, water shortages or poor water quality can significantly decrease production capabilities and lead to increased operating costs.

As water scarcity intensifies, competition increases not only within these industries but also between other water-intensive industries, such as power production and mineral processing. In regions where water is already scarce, this competition can strain relationships between industries and local communities, potentially leading to social and political tensions.

Recycling and reuse technologies
To mitigate these rivalries, many companies within the refining and chemical processing industries are increasingly turning to innovative solutions to reduce their freshwater usage and improve their water management. One of the most promising strategies is the adoption of water recycling and reuse technologies. By treating and reusing wastewater within their refineries and chemical processing plants, engineers can significantly reduce the consumption of freshwater and minimise the discharge of wastewater.

Chemistry, equipment, and processes, used judiciously, help refineries and chemical processing plants reduce freshwater intake and enhance water recycling efforts. The application of innovative chemical treatments can optimise water reuse, enabling water to be reused repeatedly by removing impurities and contaminants and preventing scaling, corrosion, and biofouling throughout cooling towers and boilers. Anti-scaling agents, for example, allow refineries and chemical processing plants to use more recycled or lower-quality water, thereby reducing the need for pristine freshwater supplies.

Corrosion inhibitors protect equipment and piping, ensuring the longevity of water reuse systems and reducing the need for frequent replacement or maintenance. By incorporating advanced equipment such as real-time monitoring systems, refinery and chemical processing plant engineers can continuously assess water quality and adjust chemical dosages and filtration processes for optimal efficiency. Technologies such as membrane filtration and reverse osmosis and processes such as advanced oxidation allow companies to purify wastewater and reuse it in cooling systems, boilers, and other stages of production. The following case history explores how a European refinery uses chemistry and equipment in tandem to ensure a reliable source of recycled water.

European refinery case history
The operators of a large petroleum refinery in a drought-stricken area in Europe wanted to implement circular water usage solutions (collecting, recovering, and recycling water resources within the system). However, they were struggling to improve and maintain the quality of their cooling make-up water.

This refinery’s engineers intended to use grey water as make-up water for cooling and other processes. However, they were limited by poor water quality, especially during upsets at the wastewater plant. Traditionally, the plant used a large quantity of hypochlorite for tertiary treatment, which required high concentrations of free chlorine to control bacterial growth in the water. High chloride concentrations in the water caused high oxidation reduction potential (ORP), which resulted in high corrosion rates.
Despite the large dosage of hypochlorite, this treatment could not prevent biofouling, which regularly caused expensive maintenance work. Additionally, any operational problem that occurred in the primary or secondary treatment prevented the use of recycled water as make-up water because of its poor quality.

Recommendations
The refinery partnered with a global producer of specialty chemicals to address the inconsistent water quality and other issues that the wastewater treatment plant was experiencing. The team of chemical specialists completed a comprehensive audit and a walk-through of the refinery’s water treatment system. During this process, laboratory technicians conducted tests to measure the components of the water and determine the best chemical application.

The team decided to implement the proprietary ClearPoint Biofilm Detection and Control programme to reduce the growth of bacteria and the rate of corrosion in the wastewater treatment plant. The benefits of using this programme typically include improved microbiological control, reduced corrosion, and reduced operating costs.
The biofilm detection and control programme comprises three parts: the proprietary OnGuard 3B analyser, proprietary chemistry, and technical expertise. The analyser employs an advanced ultrasonic probe that provides early detection of biofilm growth in water systems, thus allowing for modelling and monitoring of real-time biofilm levels. Early detection enables plant personnel to take corrective action before biofilm harms the system.

Proprietary chemistry, which includes a chlorine stabiliser chemistry used to produce a patented, in-situ stabilised active chlorine solution, provides advanced biological control. The resulting solution effectively controls both planktonic microorganisms and biofilm and does not cause any of the adverse side effects associated with using strong oxidising biocides. Specialty chemical scientists and engineers provide technical expertise to investigate problems, recommend and implement solutions, and deliver results.

Given this programme recommendation, the team of specialists set up the analyser and chemical feed to the tertiary system in the wastewater treatment plant. Additionally, they gathered baseline data for hypochlorite consumption, bacteria counts, and corrosion rates. To accomplish their overall goal of implementing circular water usage solutions, they needed to meet several objectives. For this application, the objectives determined by the plant engineers and specialty chemical team were measured by three key performance indicators (KPIs) (see Table 1).