PTQ Q4 2022 Issue

Fast response to urgent need for a wastewater solution Mobile water treatment solutions can help refineries protect their licence to operate and reduce their environmental impact when a rapid response is needed

Dominique Tassignon Mobile Water Services (MWS)

P etroleum refining and petrochemical industries unavoidably generate large volumes of wastewater and are increasingly looking at ways to improve the efficiency and reliability of the treatment of wastewater produced by their industrial sites. There are many environ - mental and economic reasons to do so, including: • Environmental protection • Compliance with local discharge standards • Lower water supply costs by reusing treated water • Reducing reliance on scarce freshwater supplies • Overall optimisation of the water footprint Effective industrial wastewater treatment is crucial to returning wastewater to the source. However, indus - trial processes can produce effluents that are challeng - ing in terms of their volume, variability, and composition. Petrochemical wastewater, specifically, contains a broad group of chemicals derived from petroleum and natural gas. During refining, the water that naturally occurs in crude oil must be removed and disposed of, along with the water used throughout the conversion process. The water from each refinery unit in each stage of the conversion process contains varying but typically high levels of suspended solids, oil and grease, heavy metals, and organics (generating high COD & BOD loads), and high bacterial and viral loads that require specific treatment. Additional challenges may come from a huge range of micropollutants that could also be present. Treating petrochemical effluent is complex and depends very much on the kind of load and the nature of the pro - cess generating the wastewater stream. It can, however, generally be done in several stages. The first is pretreat - ment of potentially high loads of suspended solids, oil and grease that would be problematic in the following steps by filtering, clarification or air flotation. The next stage involves treating specific pollutants such as heavy metals or organ - ics compounds by physicochemical or biological processes. The final step is polishing the treated effluent before dis - charge or reuse, using, if necessary, ultrafiltration and/or reverse osmosis, depending on specific quality objectives It is thus critical to assess the physical and chemical char - acteristics of the effluent to determine a cost-effective and efficient process for petrochemical wastewater treatment. Temporary mobile wastewater treatment solutions Plant operators face many other challenges. Worker and

expertise shortages, the high footprint of fixed wastewater treatment plants, and tightening budgets make it difficult to present a strong case for capital investment. The fallout has been a reluctance to invest in wastewater projects where the lifetime and return on investment (ROI) are limited, if not non-existent. In light of this, one of the attractions of mobile water services is their flexibility, as the rental payments can be covered by the operational budget, removing the need to raise capital. Mobile water service suppliers are often will - ing to enter into pay-as-you-go, multiyear contracts, which help to improve financial planning thanks to predictable, regular payments. Mobile plants A lot has changed since mobile water services were first introduced into the market. Originally, they were simply Figure 1 Mobile reverse osmosis can be used in a tertiary treatment stage for wastewater reuse applications (such as industrial air cooling, cleaning and sanitation or boiler feed water)

PTQ Q4 2022