Membrane Technologies for Water Depuration. Part 2: Three Industrial Case Studies on Water Reuse

Nowadays, the industrial sector is increasingly affected by the pressing global issue of water scarcity. Freshwater serves as a vital resource, consumed in substantial quantities for a multitude of purposes. However, a parallel concern arises from the generation of harmful wastewater during industrial processes, which is then discharged after treatment into the environment. The composition and environmental impact of industrial wastewater vary significantly depending on the specific industry. Amidst stringent environmental regulations and the escalating water scarcity crisis, industries and small enterprises are actively pursuing solutions to treat wastewater to a quality level suitable for reuse within their processes. This chapter delves into three membrane-based approaches implemented in distinct industrial sectors, namely oil and gas extraction, heavy manufacturing, and the textile industry. For the treatment and reuse of the large quantities of water produced as a by-product during the extraction of oil and natural gas, a case study based on the application of robust microfiltration membranes is reported. These advanced membranes showed superior performance and lower maintenance requirements compared to conventional technologies, providing water of higher quality for reinjection, reuse, or safe discharge. In the second case study (metalworking wastewater), ultrafiltration technology was applied in an integrated system to achieve an overall oil abatement greater than 99.9% and a ~90% COD reduction. Lastly, the application of nanofiltration in combination with advanced oxidation is reported. In this third case study, textile wastewater was treated to achieve a water stream with suitable characteristics for reuse, thus reducing the consumption of water and chemicals in the presented industrial production. Overall, the three case studies demonstrate the great potential of membrane-based technologies for treating several types of industrial wastewater to produce a suitable quality of water for reuse within the same industry. However, a few challenges persist with membrane units such as fouling and the permeability-selectivity trade-off, thus requiring an implementation with other technologies to achieve water with quality suited for reuse.