Environmental Science: Water Research & Technology最新文献

Effective wastewater treatment is critical for public health and environmental protection. In regional communities, where resources are limited, there is a need for sustainable and low-cost wastewater treatment solutions. Commonly used waste stabilisation ponds, have large land requirements, inconsistent treatment performance and high rates of evaporative water loss. High rate algal ponds (HRAPs) offer a smaller area footprint and consequentially reduced capital expenditure, enhanced treatment performance and a low maintenance alternative. HRAPs are commonly operated as continuously stirred tank reactors, at shallow depth (0.2–0.5 m) mixed by a paddlewheel. Effective wastewater treatment is then achieved by a consortium of naturally occurring, harmless microalgae and bacteria. However, there is a need to further improve their operation and the quality of the treated effluent to enhance water reuse opportunities and alleviate water insecurity concerns in rural communities. Here we uniquely propose two different operational strategies for HRAPs as the next step forward for this treatment technology. The two strategies require operation as sequencing batch reactors, which enables independent management, of hydraulic retention time and solids retention time, providing additional operational management strategies. Significantly, this offers the potential to develop influent feeding and mixing strategies to develop biofilm like assemblages of photogranules or to selectively enrich and maintain filamentous algal populations. The increased density of either photogranules or filamentous algae will enable efficient biosolids separation yielding an effluent low in suspended solids. The biomass separation may also be achieved within the HRAP avoiding the need to construct and manage additional infrastructure. The enhanced treated effluent quality increases opportunities for added value beneficial water reuse in climate change related water stressed communities. Future research is needed to validate this approach and the optimum operating conditions to achieve treatment and efficient in situ biomass separation.

Phosphorus (P) is an essential nutrient for the biological function of both animals and plants, as well as a main constituent of industrial products, including crop fertilizers, detergents, chemicals, pharmaceuticals, food and feed, and construction materials. In recent years, the imbalance between P mining and its excessive, inefficient use has led to resource depletion, runoff and water contamination. P contamination predominantly comes from agricultural, industrial, and domestic waste worldwide. The overabundance of P in water bodies has exacerbated eutrophication and related health problems, affecting aquatic life and posing risks to humans. To address global concerns about the depletion of phosphate rock (PR) reserves and alleviate associated environmental and health hazards, various physical, chemical, and biological methods are currently employed to remove and recover P from wastewater. Among these, adsorption, chemical precipitation, membrane filtration, the use of microorganisms, ion exchange, and crystallization are considered the most widely employed techniques. These conventional methods present several drawbacks, including strict control of operation, limited sensitivity to phosphate ions (PO₄³⁻) at low concentrations, high chemical and energy consumption, poor mechanical and chemical stability, limited scalability, and high costs. Recently, biopolymers, primarily polysaccharide-based technologies, have emerged as sustainable, eco-friendly, low-cost, and innovative alternatives for removing and recovering P from aqueous environments, addressing the prevailing challenges and gaps associated with conventional methods. Polysaccharides and their derivatives exhibit enhanced P removal efficiency, renewability, scalability, high mechanical and chemical strength, and non-toxicity. Although polysaccharides have been widely investigated for wastewater treatment, their involvement and mechanisms in P removal and recovery have not been systematically analyzed. Therefore, this study consolidates recent findings on polysaccharide-based materials, namely cellulose, chitosan, starch, and alginate, for the effective removal and recovery of P, filling an unaddressed area in the literature. The current review also provides a synopsis of current trends and future advancements in polysaccharide-based technologies for the removal and recovery of P. Furthermore, this review serves as a guide to the development of practical and sustainable waste and resource management systems for P, subsequently contributing to the circular bioeconomy.

Phosphorus is a non-renewable yet essential nutrient, making its recovery from wastewater crucial for resource sustainability and aquatic environmental protection. This study developed a three-chamber bio-electrodialysis (BED) system to investigate the effects of influent phosphorus concentration (155–1550 mg L⁻¹), NaCl concentration (0–12 g L⁻¹), and applied voltage (0.4–0.8 V) on phosphorus migration, enrichment, and organic matter removal. Under 155 mg L⁻¹ influent and 0.8 V conditions, the system achieved a maximum phosphorus enrichment ratio of 657% and 96.4% COD removal, whereas high-phosphorus influent (1550 mg L⁻¹) reduced enrichment to 229% due to intensified ionic competition. Moderate NaCl (≤6 g L⁻¹) enhanced conductivity and ion flux, while 12 g L⁻¹ inhibited PO₄³⁻ transport through Cl⁻ competition. Voltage elevation enriched electroactive taxa such as Gemmatimonadota and hydrogenotrophic Methanoregula, resulting in distinct anode–cathode community differentiation. SEM-EDS analysis demonstrated that pH 5–7 favored the formation of well-crystallized iron phosphate with near-theoretical Fe–P–O ratios, whereas pH 3 and pH 9 yielded poorly structured precipitates. These findings establish a coupled mechanism integrating electric-field-driven ion transport, voltage-regulated microbial cooperation, and pH-controlled crystallization, providing mechanistic insight and operational guidance for phosphorus recovery using BED systems.

Per- and polyfluoroalkyl substances (PFAS) are a large, complex group of synthetic chemicals widely used in consumer products around the world since the 50's. PFAS molecules have a chain of linked carbon and fluorine atoms and, due to the very strong C–F bonds, these chemicals do not degrade easily in the environment, are environmentally persistent and people and animals are exposed to them with multiple health effects. For these reasons, these “forever chemicals” have been declared priority pollutants. Several technologies such as adsorption, ion exchange, coagulation, sand filtration, nanofiltration, reverse osmosis, biological treatments and advanced oxidation/reduction processes have been tested to remove these very persistent and dangerous pollutants from water, with different results. Nanotechnology for water treatment is a convenient way of removing pollutants, especially through the use of nanosized iron particles. This review focuses on the possible use of zerovalent iron nanoparticles for removal of PFAS in water. As main conclusions, systems must be anaerobic and bare nanoparticles should be modified for their use in the PFAS treatment to promote a good removal.

Tiger worm toilets (TWT) are a relatively new on-site sanitation technology compared to other sanitation types (e.g. pit latrines), with some of the oldest TWTs globally now having been in continual use for only approximately 10 years. TWTs use composting worms to degrade human waste, thereby reducing fill rate and odour, and making latrine emptying safer. However, there is a significant gap in understanding the long-term user experience and maintenance requirements of TWTs. To explore this, 358 users were surveyed, and 380 TWTs were visually inspected in Pune, India. The survey employed the previously established Sanitation-Related Quality of Life (SanQoL) index to quantify TWT users' experiences. The SanQoL index showed a score of 0.94 out of 1 for TWTs, indicating a positive user experience. Additionally, 83% of users reported no need for biodigester emptying for the past decade, confirming the low-maintenance needs of TWTs. In parallel, the World Health Organization (WHO)-designed Sanitation Safety Plan was used to visually inspect and evaluate the construction quality of TWTs, revealing that poor latrine superstructure construction is a key challenge in Pune. Overall, this study, the largest such TWT survey to date, provides a substantial body of evidence needed to boost confidence in the technology and to support its expansion in other suitable settings globally.

De facto reuse (DFR) refers to the incidental or unintentional incorporation of treated wastewater into natural water bodies used as a source of drinking water. Increasing recognition of this practice has highlighted a potential risk of human exposure to various chemicals and pathogens originating from wastewater. In this study, quantitative microbial risk assessment (QMRA) was used to determine the infection risks associated with norovirus, adenovirus, enterovirus, Cryptosporidium, and Giardia for DFR in Southern Nevada (i.e., Lake Mead). Scenarios included three lake levels to encompass current (329 m) and possible scenarios associated with continued drought conditions (312 m and 297 m). Starting with observed raw wastewater pathogen concentrations at local wastewater treatment plants, risks were estimated after accounting for facility-specific wastewater treatment trains, discharge-specific dilution and decay in the environmental buffers (based on hydrodynamic modeling), and drinking water treatment. Log reduction values (LRVs) for wastewater treatment were also calibrated to observed Cryptosporidium concentrations in the environment to characterize ‘gaps’ in crediting (LRV_gap = 1.97). For the baseline lake level, the median cumulative risk of gastrointestinal infection from all pathogens was 10^−4.59 infections per person per year, with Cryptosporidium as the primary driver of risk. Risks increased significantly for the lower lake elevations but still satisfied the annual risk benchmark of 10⁻⁴. The impacts of seasonality were also studied for norovirus, indicating increased risks during fall and spring. Overall, this study demonstrates that the current design and operation of the Southern Nevada DFR system is protective of public health with respect to enteric pathogen exposure, even if the current Colorado River Basin drought continues or worsens.

Groundwater contaminated by radioactive elements, such as uranium and radium, poses significant risks to ecosystems and human health due to their persistence, toxicity, and bioaccumulation potential. This review summarizes recent advances in uranium/radium-contaminated groundwater remediation technology. The characteristics, migration, and transformation of uranium/radium in groundwater are analyzed, emphasizing how their speciation and environmental behavior determine the selection and effectiveness of remediation technologies. The work comprehensively examines four primary removal methods: adsorption, membrane filtration, electrochemical treatment, and bioremediation, elucidating their fundamental principles, application scenarios, and limitations, while critically examining current bottlenecks and future research directions. Adsorption leverages materials like zeolites, activated carbon, and novel composites for targeted removal, yet faces regeneration challenges and ionic interference. Membrane technologies achieve >95% rejection but suffer from fouling and high costs. Electrochemical methods enable efficient recovery via capacitive deionization or electrodeposition, though energy consumption and electrode stability require optimization. Bioremediation exploits microbial reduction and plant uptake for eco-friendly treatment but struggles with slow kinetics and environmental sensitivity. Future research should focus on enhancing existing technologies, exploring disruptive innovations (e.g., advanced materials, hybrid systems), and establishing sustainable frameworks to achieve efficient, intelligent, and sustainable remediation of uranium/radium-contaminated groundwater.

An innovative analytical approach was established for quantifying Fe(VI) concentrations in the 0.47–40 μM range. This technique exploited the electron transfer reaction between Fe(VI) and N,N-diethyl-p-phenylenediamine (DPD), generating a stable radical cation species (DPD˙⁺) with characteristic absorbance at 551 nm in spectroscopic detection. The increase in the absorbance of the formed DPD˙⁺ at 551 nm was linearly related to the added Fe(VI) concentration. The formed DPD˙⁺ was found to be stable in synthetic water samples at pH 5–7 and real water samples. The stoichiometric relationship of the formed DPD˙⁺ to Fe(VI) was 1 : 1 in reaction of Fe(VI) with excess DPD in 300 mM phosphate buffer at pH 6, which was lower than that in lower concentration of phosphate, due to the inhibiting impact of phosphate on the oxidation capacity of Fe(V) with DPD. Demonstrating a molar absorptivity of 2.08 × 10⁴ M⁻¹ cm⁻¹ at 551 nm, the Fe(VI)–DPD method exhibited broad applicability while maintaining accuracy across diverse environmental water matrices. This methodology exhibited superior detection sensitivity, with detection limits established at 0.47 μM (LOD) and 1.57 μM (LOQ). The oxidizing capacity of the complexed Fe(V) followed the order: carbonate–Fe(V) > borate–Fe(V) > phosphate–Fe(V) > pyrophosphate–Fe(V). The ratio of the formed DPD˙⁺ to consumed Fe(VI) decreased with the increasing concentration ratio of pyrophosphate to Fe(VI) (2.5–3.6) at pH 5, indicating that pyrophosphate inhibited the oxidizing capacity of Fe(VI) to Fe(V) using DPD. The developed DPD probe method demonstrated reliable applicability in characterizing Fe(VI) reaction pathways due to its high sensitivity (2.08 × 10⁴ M⁻¹ cm⁻¹) and minimal matrix interference.

Quinone outside inhibitor fungicides (QoIs) are widely used across the United States, with common QoIs (e.g., azoxystrobin, pyraclostrobin) regularly detected in water resources that could serve as drinking water supplies in agriculturally dominated watersheds. Here, we explored the fate of several QoIs during simulated water treatment via coagulation/flocculation, chemical (lime-soda) softening, chemical disinfection with free chlorine, and granular activated carbon (GAC). Jar tests with Iowa River water found little QoI removal during coagulation/flocculation. Trifloxystrobin and kresoxim-methyl underwent base-promoted hydrolysis at pH values and over timescales used in lime-soda softening, with liquid chromatography-tandem mass spectrometry (LC-MS/MS) and nuclear magnetic resonance (NMR) data identifying known acid metabolites as major hydrolysis products. Select QoIs, kresoxim-methyl, pyraclostrobin, azoxystrobin, fenamidone, and dimoxystrobin, were reactive toward free chlorine under conditions and over timescales relevant for chemical disinfection, resulting in persistent, often chlorinated, transformation products. Notably, we observed distinct reaction sites during chlorination for each of the five QoIs found to be reactive toward free chlorine, including some cases where the biologically active moiety of the parent molecule was conserved. Successful management of QoIs can likely be achieved with GAC, which quickly removed all QoIs via sorption. Outcomes of this work will help to improve exposure assessments to QoIs and their transformation products through drinking water, while also identifying practical approaches for their removal during drinking water treatment.