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The freshwater scarcity and inadequate access to clean water globally have rallied tremendous efforts in developing robust technologies for water purification and decontamination, and heterogeneous catalysis is a highly-promising solution. Sub-nanometer-confined reaction is the ultimate frontier of catalytic chemistry, yet it is challenging to form the angstrom channels with distributed atomic catalytic centers within, and to match the internal mass transfer and the reactive species' lifetimes. Here, we resolve these issues by applying the concept of the angstrom-confined catalytic water contaminant degradation to achieve unprecedented reaction rates within 4.6 Å channels of two-dimensional laminate membrane assembled from monolayer cobalt-doped titanium oxide nanosheets. The demonstrated degradation rate constant of the target pollutant ranitidine (1.06 ms ) is 5-7 orders of magnitude faster compared with the state-of-the-art, achieving the 100% degradation over 100 h continuous operation. This approach is also ~100% effective against diverse water contaminates with a retention time of <30 ms, and the strategy developed can be also extended to other two-dimensional material-assembled membranes. This work paves the way towards the generic angstrom-confined catalysis and unravels the importance of utilizing angstrom-confinement strategy in the design of efficient catalysts for water purification.

For removal of radium from saline waters in Upper Silesian mines, several methods of purification have been developed. The most efficient one is based on application of barium chloride, which was implemented in full technical scale in two Polish coal mines several years ago. Very good results of purification have been achieved—the removal efficiency exceeding 95 % of the initial activity. Another possibility for the removal of different ions from salty waters and brines is the application of zeolites. We found that technique as a very promising method for removal of not only radium isotopes from mine waters but also other ions (barium, iron, manganese). Treatment of several various water samples has been done to assess the removal efficiency for natural radionuclides. Preliminary results show very good effects for radium isotopes as well as for barium ions. In the paper, a short description of laboratory results of the purification of mine waters with application of synthetic zeolites is presented.

Reuse of wastewater is a practice that has been employed all over the world, mainly in agriculture, where the main aim is to reduce the demand for water and provide nutrients. However, these waters for reuse often have excessive amounts of pathogenic microorganisms, requiring a specific disinfection step even after being subjected to a purification process. Thus, this research aimed to evaluate the potential use of calcium hypochlorite and sodium hypochlorite as disinfectant agents for the sanitary effluent of the treatment system based on constructed wetlands for later reuse. Disinfection tests were carried out in batch, using three dosages of hypochlorite (5, 10 and 15 mg.L−1) and different contact. In all disinfection tests, inactivation of indicator microorganisms (total coliforms and E. coli) was considered effective for the two disinfectant agents adopted, satisfying the criteria for reuse according to the World Health Organization (WHO). There was no formation of trihalomethanes after disinfection tests.

An alternative material to activated carbon for water remediation is reported: a porous material based on crosslinked cyclodextrins that is better than activated carbons at adsorbing a range of pharmaceuticals, pesticides and other anthropogenic pollutants. Near-instant removal of organic micropollutants from water Water purification and remediation is often carried out using various forms of activated carbon; it is inexpensive, but only partially removes many organic pollutants. However, regenerating activated carbon for reuse is energy intensive, requiring high temperatures, and performance decreases upon recycling. Now William Dichtel, Damian Helbling and colleagues have developed an alternative to activated carbon for water remediation: a high-surface-area, mesoporous polymer of β-cyclodextrin. Not only does the material outperform activated carbons at adsorbing a range of pharmaceuticals, pesticides and other pollutants, but it is easily regenerated by washing at room temperature. The global occurrence in water resources of organic micropollutants, such as pesticides and pharmaceuticals, has raised concerns about potential negative effects on aquatic ecosystems and human health 1 , 2 , 3 , 4 , 5 . Activated carbons are the most widespread adsorbent materials used to remove organic pollutants from water but they have several deficiencies, including slow pollutant uptake (of the order of hours) 6 , 7 and poor removal of many relatively hydrophilic micropollutants 8 . Furthermore, regenerating spent activated carbon is energy intensive (requiring heating to 500–900 degrees Celsius) and does not fully restore performance 9 , 10 . Insoluble polymers of β-cyclodextrin, an inexpensive, sustainably produced macrocycle of glucose, are likewise of interest for removing micropollutants from water by means of adsorption 11 . β-cyclodextrin is known to encapsulate pollutants to form well-defined host–guest complexes, but until now cross-linked β-cyclodextrin polymers have had low surface areas and poor removal performance compared to conventional activated carbons 11 , 12 , 13 . Here we crosslink β-cyclodextrin with rigid aromatic groups, providing a high-surface-area, mesoporous polymer of β-cyclodextrin. It rapidly sequesters a variety of organic micropollutants with adsorption rate constants 15 to 200 times greater than those of activated carbons and non-porous β-cyclodextrin adsorbent materials 7 , 8 , 11 , 12 , 13 . In addition, the polymer can be regenerated several times using a mild washing procedure with no loss in performance. Finally, the polymer outperformed a leading activated carbon for the rapid removal of a complex mixture of organic micropollutants at environmentally relevant concentrations. These findings demonstrate the promise of porous cyclodextrin-based polymers for rapid, flow-through water treatment.

Phosphorus (P) losses from agricultural soils have caused surface water quality impairment in many regions of the world, including The Netherlands. Due to the large amounts of P accumulated in Dutch soils, the generic fertilizer and manure policy will not be sufficient to reach in time the surface water quality standards of the European Water Framework Directive. Additional measures must be considered to further reduce P enrichment of surface waters. One option is to immobilize P in soils or manure or to trap P when it moves through the landscape by using reactive materials with a large capacity to retain P. We characterized and tested two byproducts of the process of purification of deep groundwater for drinking water that could be used as reactive materials: iron sludge and iron‐coated sand. Both materials contain low amounts of inorganic contaminants, which also have a low (bio)availability, and bound a large amount of P. We could describe sorption of P to the iron sludge in batch experiments well with the kinetic Freundlich equation (Q = a × tm × Cn). Kinetics had a large influence on P sorption in batch and column experiments and should be taken into account when iron‐containing materials are tested for their capability to immobilize or trap P. A negative aspect of the iron sludge is its low hydraulic conductivity; even when mixed with pure sand to a mixture containing 20% sludge, the conductivity was very low, and only 10% sludge may be needed before application is possible in filters or barriers for removing P from groundwater. Due to its much higher hydraulic conductivity, iron‐coated sand has greater potential for use under field conditions. Immobilizing P could be an option for using iron sludge as a reactive material.

Accurate identification of wet and dry weather periods at sub-hourly time intervals is important for the description and control of processes directly influenced by rainfall, such as infiltration into urban drainage systems, purification processes in wastewater treatment plants, or effective irrigation systems. It is also necessary for monitoring and modeling rainfall itself. Traditional instrumentation used to measure rainfall (rain gauges and radars) often fails to detect the transition between dry and wet weather at sufficient spatial and temporal resolution. Opportunistic sensing has become a promising approach in hydrology to overcome these deficits without drastically increasing the cost of measuring campaigns. In this study, we identify dry and wet weather periods using autonomous and inexpensive transmission line-type electromagnetic sensors, primarily intended for soil water content measurement. Four transmission line-type electromagnetic sensors, a tipping bucket rain gauge, and a laser precipitation monitor were installed in an urban catchment for an experimental period of 3 months during the summer. An algorithm for the reliable detection of the onset and end of precipitation episodes was developed for use with the sensors. Our analysis demonstrates that transmission line-type electromagnetic sensors provide results with accuracy similar to, and with five times greater sensitivity than a tipping bucket rain gauge. However, the sensors produced false-negative results more than 1.6% of the time (i.e., 25% of the received rain). Nevertheless, the low specificity of the sensors is not critical when they are used in combination with rain gauges or other sensors that are less prone to falsely detect wet periods.

Industrial development, energy production and mining have led to dramatically increased levels of environmental pollutants such as heavy metal ions, metal cyanides and nuclear waste. Current technologies for purifying contaminated waters are typically expensive and ion specific, and there is therefore a significant need for new approaches. Here, we report inexpensive hybrid membranes made from protein amyloid fibrils and activated porous carbon that can be used to remove heavy metal ions and radioactive waste from water. During filtration, the concentration of heavy metal ions drops by three to five orders of magnitude per passage and the process can be repeated numerous times. Notably, their efficiency remains unaltered when filtering several ions simultaneously. The performance of the membrane is enabled by the ability of the amyloids to selectively absorb heavy metal pollutants from solutions. We also show that our membranes can be used to recycle valuable heavy metal contaminants by thermally reducing ions trapped in saturated membranes, leading to the creation of elemental metal nanoparticles and films. Hybrid membranes made from protein amyloid fibrils and activated porous carbon can be used to remove heavy metal ions and radioactive waste from water.

Although surface water treatment presents a good solution for pollutants in rivers and freshwater lakes, the purification process itself presents a great threat to the aquatic environment through aluminum waste disposal. Recent studies have introduced coagulants recovery from treatment sludge as a green solution for waste handling and cost reduction. This article aims to evaluate repeated aluminum coagulants recovery from sludge using sulfuric acid. The waste from El-Sheikh Zaid Water Treatment Plant (ESZ-WTP) was characterized, then sequential coagulants recovery using optimum conditions was conducted. In addition, treated water was analyzed to determine the efficiency of the obtained coagulants and their influence on treated water quality. Sequential coagulants recovery using acidification revealed that no metals accumulation took place in the produced coagulants until the third recovery from ESZ-WTP sludge. On the other hand, a noticeable increase in trihalomethanes was detected in the treated water, especially using the third recovered coagulant. In conclusion, sequential coagulants recovery and usage in water treatment is an attractive alternative for single-use original coagulant in ESZ-WTP but for no more than three sequential recoveries. It is advisable to apply a fresh coagulant every three sequential recoveries to enrich the aluminum content and regenerate the sludge before restarting the recovery process.

As population growth continues to outpace development of water infrastructure in many countries, desalination (the removal of salts from seawater) at high energy efficiency will likely become a vital source of fresh water. Due to its atomic thinness combined with its mechanical strength, porous graphene may be particularly well-suited for electrodialysis desalination, in which ions are removed under an electric field via ion-selective pores. Here, we show that single graphene nanopores preferentially permit the passage of K + cations over Cl − anions with selectivity ratios of over 100 and conduct monovalent cations up to 5 times more rapidly than divalent cations. Surprisingly, the observed K + /Cl − selectivity persists in pores even as large as about 20 nm in diameter, suggesting that high throughput, highly selective graphene electrodialysis membranes can be fabricated without the need for subnanometer control over pore size. Sub-nanometer graphene nanopores are usually required to create graphene-based reverse osmosis membranes. Here, Rollings et al. show that membranes with larger pores are highly ion selective and a hundred times more permeable to potassium ions than to chloride ions, making them useful for electrodialysis.