Electrochemical oxidation processes for PFAS removal from contaminated water and wastewater: fundamentals, gaps and opportunities towards practical implementation.

Electrochemical oxidation (EO) is emerging as one of the most promising methods for the degradation of recalcitrant per- and poly-fluoroalkyl substances (PFASs) in water and wastewater, as these compounds cannot be effectively treated with conventional bio- or chemical approaches. This review examines the state of the art of EO for PFASs destruction, and comprehensively compares operating parameters and treatment performance indicators for both synthetic and real contaminated water and wastewater media. The evaluation shows the need to use environmentally-relevant media to properly quantify the effectiveness/efficiency of EO for PFASs treatment. Additionally, there is currently a lack of quantification of sorption losses, resulting in a likely over-estimation of process' efficiencies. Furthermore, the majority of experimental results to date indicate that short-chain PFASs are the most challenging and need to be prioritized as environmental regulations become more stringent. Finally, and with a perspective towards practical implementation, several operational strategies are proposed, including processes combining up-concentration followed by EO destruction.

Selective laser assisted impairment of reverse osmosis membranes.

Monitoring the loss of integrity in reverse osmosis (RO) membranes is crucial for protection of public health as small imperfections can result in catastrophic pathogen outbreaks. However, understanding the phenomena accompanying the loss of integrity in RO membranes relies on properly characterizing and interpreting performance data. Reproducing chemical and mechanical damage in model membranes that mimic the conditions of real-time operation is difficult. Mechanical impairment is particularly challenging, since one needs to damage selectively and in a controlled manner (producing holes of desired size) the barrier (polyamide) and/or the support layer (polyether sulfone and polyester). In this work we develop a straightforward approach to produce arrays of micro-holes in a commercially available RO membrane employing nanosecond pulsed laser ablation. The new approach is used to prepare four samples with different number of holes with constant diameter and increasing hole depth. These samples were further tested to reveal the impairment impact on filtration performance. It was observed that the flux was linked with the laser pulse density/penetration.•Uniform radius defects were created in RO membranes.•Higher pulse density leads to deeper defects.•Ablation of all three layers can be attained.

Reverse osmosis integrity monitoring in water reuse: The challenge to verify virus removal - A review.

A reverse osmosis (RO) process is often included in the treatment train to produce high quality reuse water from treated effluent for potable purposes because of its high removal efficiency for salinity and many inorganic and organic contaminants, and importantly, it also provides an excellent barrier for pathogens. In order to ensure the continued protection of public health from pathogen contamination, monitoring RO process integrity is necessary. Due to their small sizes, viruses are the most difficult class of pathogens to be removed in physical separation processes and therefore often considered the most challenging pathogen to monitor. To-date, there is a gap between the current log credit assigned to this process (determined by integrity testing approved by regulators) and its actual log removal capability as proven in a variety of laboratory and pilot studies. Hence, there is a challenge to establish a methodology that more closely links to the theoretical performance. In this review, after introducing the notion of risk management in water reuse, we provide an overview of existing and potentially new RO integrity monitoring techniques, highlight their strengths and drawbacks, and debate their applicability to full-scale treatment plants, which open to future research opportunities.

Virus removal and integrity in aged RO membranes.

Membrane ageing reduces the quality of the filtered water. Therefore, in order to warrant public health, monitoring membrane performances are of utmost importance. Reverse osmosis (RO) membranes are generally used to remove viruses and salt. However, there is no detailed study demonstrating the impact of aged membrane on the rejection of viruses and of membrane integrity indicators. In this paper, the impact of hypochlorite induced RO ageing on the rejection of a virus surrogate (MS2 phage) and four membrane integrity indicators (salt, dissolved organic matter, rhodamine WT and sulphate) was evaluated. Hypochlorite exposure was either active (under filtration) or passive (soaking), and the changes of the membrane surface chemistry were characterised using several autopsy techniques. Under this accelerated ageing condition, the introduction of chlorine in the membrane chemistry and the breakage of amide bonds caused an increase of the water permeability and a decrease of the virus surrogate's and indicators' rejection. Ageing resulted in a more negatively charged membrane and also in a higher hydrophobicity, which lead to the adsorption of MS2 phage. Despite severe physical membrane damage leading to a reduction of salt rejection to 1.2 log (94%), the minimum rejection of MS2 phage stayed on or above 4 log.

Enhanced methods for conditioning, storage, and extraction of liquid and solid samples of manure for determination of steroid hormones by solid-phase extraction and gas chromatography-mass spectrometry.

Hormones are among the highest-impact endocrine disrupters affecting living organisms in aquatic environments. These molecules have been measured in both wastewater and sewage sludge. Analytical techniques for such matrices are well described in the literature. In contrast, there is little information about the analysis of hormones in animal waste. The objectives of this study were, first, to propose a method for conditioning swine manure samples (addition of formaldehyde, separation of the solid and liquid phases, and duration of storage) in order to determine hormones in the liquid fraction of manure by solid-phase extraction (SPE) coupled with gas chromatography-mass spectrometry (GC-MS). Our results showed that analysis of hormones was affected by matrix changes which occurred during freezing and thawing and after addition of formaldehyde, an additive frequently used to preserve environmental samples. Thus, our results argue for the conditioning of samples without formaldehyde and for separating the solid and liquid fractions of manure before freezing. Second, this study reports on the use of a liquid extraction method coupled with SPE and GC-MS analysis for determination of hormones in the solid fraction of manure. Under the conditions selected, hormone recoveries were between 80 and 100%. Finally, the optimized method was used to quantify hormones in both liquid and solid fractions of swine manure from different breeding units. High levels of estrone and α-estradiol were found in samples whereas ß-estradiol was detected in smaller amounts. Estriol and progesterone were mainly found in manure from the gestating sow building whereas testosterone was detected in manure from male breeding buildings.