Alongside the rising global water demand, continued stress on current water supplies has sparked interest in using nontraditional source waters for energy, agriculture, industry, and domestic needs. Membrane technologies have emerged as one of the most promising approaches to achieve water security, but implementation of membrane processes for increasingly complex waters remains a challenge. The technical feasibility of membrane processes replacing conventional treatment of alternative water supplies (e.g., wastewater, seawater, and produced water) is considered in the context of typical and emerging water quality goals. This review considers the effectiveness of current technologies (both conventional and membrane based), as well as the potential for recent advancements in membrane research to achieve these water quality goals. We envision the future of water treatment to integrate advanced membranes (e.g., mixed-matrix membranes, block copolymers) into smart treatment trains that achieve several goals, including fit-for-purpose water generation, resource recovery, and energy conservation.

Per-and polyfluoroalkyl substances (PFAS), which are present in many waters, have detrimental impacts on human health and the environment. Reverse osmosis (RO) and nanofiltration (NF) have shown excellent PFAS separation performance in water treatment; however, these membrane systems do not destroy PFAS but produce concentrated residual streams that need to be managed. Complete destruction of PFAS in RO and NF concentrate streams is ideal, but long-term sequestration strategies are also employed. Because no single technology is adequate for all situations, a range of processes are reviewed here that hold promise as components of treatment schemes for PFAS-laden membrane system concentrates. Attention is also given to relevant

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Water shortages are widely prevalent in developing countries, affecting lives of people including schoolchildren, who miss classes while fetching water for daily use. A typical case was that of Mnyundo Primary School in Tanzania, East Africa. A rainwater harvesting (RWH) system was then constructed because of easy adaptability of the technology. The purpose of this study is sustainability evaluation. The evaluation considered construction details, level of water supply service, potential for sustainability and replication. Coarse screen, first flush tank, and sedimentation tank were included for maintaining drinkable water quality through particle load reduction. The water level gauge incorporated enables easy monitoring of water usage, while the provided training and operational manual are a practical guide on system management for the users. Local labor, material and techniques used, are recommended for capacity building, sense of ownership, and cost reduction. Companies’ involvement is encouraged by providing financial support to the schools as their corporate social responsibility. RWH is thus suggested as a sustainable alternative for drinking water supply.

In the inland region of Southern California, a 116-km brine line distribution system transports brackish desalination brine to the coast for treatment and ocean discharge; however, solid precipitation and pipeline scaling have occurred in the brine line. This case study investigated brine chemistry and solid precipitation behaviors in the brine line system. Brine chemical composition at multiple sites along the brine line was measured, and the theoretical type and amount of solid formation was predicted using chemical modeling. Lab-scale simulation experiments were performed to evaluate the impacts of antiscalant application on solid formation in the brine line. Sampling data showed that pre-existing solids discharged from inland brackish desalination plants accumulated in the brine line which may lead to scaling problems. Chemical modeling predicted that calcite, dolomite, silica, and hydroxyapatite were oversaturated but not precipitated. Lab simulation data suggested that the delayed solid formation was mostly due to the presence of antiscalants, especially secondary antiscalants in low flow turbulence conditions. Results suggests that, in order to minimize scaling issues in the brine line infrastructure, two strategies of active on-site brine pretreatment to remove antiscalants and hardness ions and operational optimization on the brine line for better flow control and real-time monitoring should be considered.

Highlights Data and models were reviewed to estimate energy consumption in potable water reuse. Entire reuse schemes, both direct and indirect, require 1.2 to 2.1 kWh/m 3 . Lowest-energy options include non-RO indirect and RO-based direct potable reuse. Potable reuse requires much less energy than seawater desalination. Pipe network updates and high-permeability membranes would reduce energy use.

Natural organic matter (NOM) complicates water treatment and causes formation of disinfection byproducts (DBPs). NOM is removed well by nanofiltration (NF) but causes extensive membrane fouling, especially in the presence of divalent cations. This research investigated a hybrid electrodialysis-nanofiltration (ED−NF) system to treat freshwaters containing hardness and NOM. ED removes most ions but little to no NOM, and the ED diluate is, then, treated with NF to remove NOM with reduced fouling. Subsequently, some or all of the ED concentrate can be mixed with the NF permeate to increase water recovery, limit NOM concentration (and thereby reduce DBPs), and control the ion content. Compared to NF alone, ED−NF increases product water yield. NF fouling was reduced by the removal of divalent cations in ED. Spectroscopic and resonant scattering measurements of fouled membranes near the calcium K-edge reveal a significant contribution to NF fouling by calcium bridging between carboxyl groups in NOM and on the membrane surface. This novel ED−NF system allows several control "knobs" to increase water recovery and reduce DBP formation potential by adjusting ED water recovery, ED diluate (and concentrate) ionic composition, and the fraction of concentrate remixed with NF permeate to form the product water.