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In this study, pomegranate peels (PPs) as an abundant fruit processing waste was used to produce cost-effective, eco-friendly, and high-quality activated carbon. The produced carbon (fossil free activated carbon) was used for immobilizing laccase to remove a range of emerging pollutants namely diclofenac, amoxicillin, carbamazepine, and ciprofloxacin from water and wastewater. The loaded activated carbon by laccase (LMPPs) and the unloaded one (MPPs) were characterized using advanced surface chemistry analysis techniques. MPPs was found to have a porous structure with a large surface area and an abundance of acidic functional groups. Laccase immobilization reduced surface area but added active degradation sites. The optimal immobilization parameters were determined as pH 4, 35 oC, and a laccase concentration of 2.5 mg/mL resulting in a 69.8% immobilization yield. The adsorption of the emerging pollutant onto MPPs is best characterized as a spontaneous endothermic process that adheres to the Langmuir isotherm and first-order kinetics. Using synergistic adsorption and enzymatic degradation, the target pollutants (50 mg/L) were eliminated in two hours. In both water types, LMPPs outperformed MPPs. This study shows that pomegranate peels can effectively be harnessed as an enzyme carrier and adsorbent for the removal of emerging pollutants even from a complex sample matrix. The removal of contaminants from wastewater lasted five cycles, whereas it continued up to six cycles for water.

This study addressed the fouling issue in membrane distillation (M.D.) technology, a promising method for water purification and wastewater reclamation. To enhance the anti-fouling properties of the M.D. membrane, a tin sulfide (TS) coating onto polytetrafluoroethylene (PTFE) was proposed and evaluated with air gap membrane distillation (AGMD) using landfill leachate wastewater at high recovery rates (80% and 90%). The presence of TS on the membrane surface was confirmed using various techniques, such as Field Emission Scanning Electron Microscopy (FE-SEM), Fourier Transform Infrared Spectroscopy (FT-IR), Energy Dispersive Spectroscopy (EDS), contact angle measurement, and porosity analysis. The results indicated the TS-PTFE membrane exhibited better anti-fouling properties than the pristine PTFE membrane, and its fouling factors (FFs) were 10.4–13.1% compared to 14.4–16.5% for the PTFE membrane. The fouling was attributed to pore blockage and cake formation of carbonous and nitrogenous compounds. The study also found that physical cleaning with deionized (DI) water effectively restored the water flux, with more than 97% recovered for the TS-PTFE membrane. Additionally, the TS-PTFE membrane showed better water flux and product quality at 55 °C and excellent stability in maintaining the contact angle over time compared to the PTFE membrane.

The Danube is one of the largest transboundary rivers word-wide, having several tributaries. The discharges from industrial activities and wastewater treatment facilities affect the river's aquatic environment. These discharges pose a serious risk to aquatic life by degrading the water and sediment quality. Therefore, 16 Polycyclic Aromatic Hydrocarbons (PAHs) compounds in six different locations were examined along the river over 12 months to investigate the temporal and special variations of the compounds in water and sediment. The findings highlighted a broad variance range in PAHs concentration in water within a year, ranging from 224.85 ng/L in summer to 365.87 ng/L in winter, whereas PAHs in sediment samples recorded values ranging from 316.72 ng/g in dry weight in summer to 422.98 ng/g in dry weight in winter. The overall results indicate that the putative anthropogenic sources of PAHs were of pyrolytic and pyrogenic origin, with pyrogenic sources being more prominent. Generally, except for Acenaphthylene and Fluorene concentrations, the eco-toxicological concerns for the aquatic environment of the Danube River do not pose a significant threat. In addition, the combined impact of the 16 PAHs pollutants in sediments suggests a low chance for negative biological impacts and low ecological risk. The total ILCR for both children and adults is more than 1/104 in all seasons, with the highest values recorded in spring followed by winter time, which becomes a matter of urgency.

Funding Information: This research was funded by the Ministry of Higher Education, Malaysia under the HICoE with the grant number R.J090301.7851.4J433 and by the Universiti Teknologi Malaysia under Hi-Tech(F4) Research Grant with the grant number Q.J130000.4609.00Q14. Publisher Copyright: © 2023 by the authors. In this work, MXene as a hydrophilic 2D nanosheet has been suggested to tailor the polyphenylsulfone (PPSU) flat sheet membrane characteristics via bulk modification. The amount of MXene varied in the PPSU casting solution from 0–1.5 wt.%, while a series of characterization tools have been employed to detect the surface characteristics changes. This included atomic force microscopy (AFM), scanning electron microscopy (SEM), contact angle, pore size and porosity, and Fourier-transform infrared spectroscopy (FTIR). Results disclosed that the MXene content could significantly influence some of the membranes’ surface characteristics while no effect was seen on others. The optimal MXene content was found to be 0.6 wt.%, as revealed by the experimental work. The roughness parameters of the 0.6 wt.% nanocomposite membrane were notably enhanced, while greater hydrophilicity has been imparted compared to the nascent PPSU membrane. This witnessed enhancement in the surface characteristics of the nanocomposite was indeed reflected in their performance. A triple enhancement in the pure water flux was witnessed without compromising the retention of the membranes against the Cu2+, Cd2+ and Pd2+ feed. In parallel, high, and comparable separation rates (>92%) were achieved by all membranes regardless of the MXene content. In addition, promising antifouling features were observed with the nanocomposite membranes, disclosing that these nanocomposite membranes could offer a promising potential to treat heavy metals-containing wastewater for various applications.

Funding Information: The ÚNKP-22-3-I-PE-5 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund supported this research. The Stipendium Hungaricum Scholarship partially supported the study. Publisher Copyright: © 2023 The Author(s) This study presented for the first time a comprehensive measurement campaign of 16 PAHs along the Euphrates River for five months, in both water and sediment samples. Our study revealed that the PAHs contamination increased along the flow direction due to the increasing non-point pollution and the return flows of agriculture. The 5–6 rings PAHs were dominant in water and sediment samples with an average of 42 % and 50 %, respectively. The diagnostic ratios of PAHs suggest that the pollution of these compounds originated mainly from petroleum product combustions. The carcinogenic PAHs formed 46 % and 55 % of the total measured compounds in water and sediment samples, respectively, which highlights potential ecological and human health risks. Based on sediment quality guidelines (SQGs), most sites exhibit an effect range between low and medium. The calculated incremental lifetime cancer risk (ILCR) for adult and children were in the 10−2–10−3 range, which is 3–6-fold higher than what was reported in the literature. These observations call for urgent attention from environmental authorities of countries sharing this key water source in Western Asia.

This study reports on the impact of elevated recovery (i.e., 80%, 85%, and 90%) on the fouling and performance of air gap membrane distillation (AGMD) with real seawater and landfill leachate wastewater samples using polytetrafluoroethylene (PTFE) polymer membranes. Increasing the feed temperature from 55 °C to 65 °C improved the water flux of seawater and wastewater and shortened the operating time by 42.8% for all recoveries. The average water flux in the 80%, 85%, and 90% recovery experiments at the 65 °C feed temperature was 32%, 37.32%, and 36.7% higher than the case of 55 °C for the same recoveries. The water flux decline was more severe at a higher temperature and recovery. The highest flux decline was observed with a 90% recovery at 65 °C feed temperature, followed by an 85% recovery at 65 °C. Close examination of the foulants layer revealed that seawater formed a cake fouling layer made predominantly of metal oxides. In contrast, the landfill leachate fouling was a combination of pore blocking and cake formation, consisting mainly of carbonous and nitrogenous compounds. Physical cleaning with deionized (DI) water at 55 °C and 65 °C and chemical cleaning with hydrogen peroxide (H2O2) were investigated for their efficiency in removing membrane foulants. Analytical results revealed that seawater fouling caused membrane pore blockage while wastewater fouling formed a porous layer on the membrane surface. The results showed that membrane cleaning with hydrogen peroxide restored >97% of the water flux. Interestingly, the fouling factor in seawater tests was 10%, while it was 16% for the wastewater tests.

Funding Information: This research received funding from Ministry of the Environment in Finland RAKI2 project VN/2250/2019 and from Maa- ja vesitekniikan tuki r.y. (MVTT). Funding Information: This work was supported by Maa- ja Vesitekniikan tuki r.y. (MVTT). The authors are grateful to Aino Peltola for her assistance with the laboratory analyses. The authors are thankful to Antti Louhio’s help with designing the lab reactors. The authors would also like to acknowledge the support from Onni Lehtikuja with conducting laboratory tests. Publisher Copyright: © 2022 by the authors. Membrane contactor technology affords great opportunities for nitrogen recovery from waste streams. This study presents a performance comparison between lab- and pilot-scale membrane contactors using landfill leachate samples. Polypropylene (PP) and polytetrafluoroethylene (PTFE) fibers in different dimensions were compared in terms of ammonia (NH3) recovery on a lab scale using a synthetic ammonium solution. The effect of pre-treating the leachate with tannin coagulation on nitrogen recovery was also evaluated. An ammonia transfer on the lab and pilot scale was scrutinized using landfill leachate as a feed solution. It was found that PTFE fibers performed better than PP fibers. Among PTFE fibers, the most porous one (denoted as M1) had the highest NH3 flux of 19.2 g/m2.h. Tannin pre-treatment reduced fouling and increased NH3, which in turn improved nitrogen recovery. The mass transfer coefficient of the lab-scale reactor was more than double that of the pilot reactor (1.80 × 10−7 m/s vs. 4.45 × 10−7 m/s). This was likely attributed to the difference in reactor design. An analysis of the membrane surface showed that the landfill leachate caused a combination of inorganic and organic fouling. Cleaning with UV and 0.01 M H2O2 was capable of removing the fouling completely and restoring the membrane characteristics.

Funding Information: The ÚNKP-22–3-I-PE-12 (Osamah J. Al-sareji) New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund supported this research. Publisher Copyright: © 2023 The Authors This work reports the removal of diclofenac, amoxicillin, carbamazepine, and ciprofloxacin by utilizing three commercially available granular activated carbons (GACs) (Activated carbon, Silcarbon, and Donau) loaded with laccase. Adsorption was used to successfully immobilize laccase on the GACs, as revealed by scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDX) and Fourier transform infrared spectroscopy (FTIR). In the three types of GACs tested, pH 5, 30 °C, and 2 mg mL−1 laccase content were found to be the optimum immobilization parameters. Laccase immobilization yields of 65.2%, 63.1%, and 62.9% were achieved with activated carbon, Silcarbon, and Donau respectively. The adsorption behaviors of the pharmaceuticals onto the tested activated carbons are best described as a spontaneous endothermic process that follows Langmuir isotherm and first-order kinetics. The reusability of the immobilized enzyme was evaluated using 2, 2′-azino-bis 3-ethylbenzothiazole-6-sulphonic acid (ABTS) as a substrate within six cycles for all adsorbents. In 120 mins, nearly a complete removal of the pharmaceutical compounds (50 mg L−1) was obtained in the case of activated carbon type and more than 90% for other adsorbent types when synergistic adsorption and enzymatic degradation were applied. With adsorption alone, 74% removal was obtained with activated carbon and < 56% for other adsorbents. The finding of this study suggests that biochar produced from coconut shell (same as the one used in this study) can effectively be used as a substrate and adsorbent for pharmaceutical removal. This enzymatic physical removal system has the potential to be applied on a large-scale.

Funding Information: The authors are appreciative of the warm work of the Co-Editor in Chief, Associate Editor, and anonymous reviewers earnestly. The authors thank the support provided by Aalto University, Finland, and Liverpool John Moors University, United Kingdom in different facilities. The opinions or views stated in this article are those of its authors. We deeply thank Dr. Zaid Al-Gazali from Nasiriyah Teaching Hospital, Ministry of Health, Al-Nasiriyah, Thi-Qar, Iraq for his logistic support. Omer Al-Obaidi, Firas Ali, Mohammed Jasim, Tahseen Salah and Redha Ahmed from the Ministry of Health, Iraq are deeply acknowledged in this work for their assistance in the sampling campaign. Funding Information: ÚNKP-22-3-I-PE-5 (Ruqayah Ali Grmasha) New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund supported this research. Publisher Copyright: © 2023 The Authors Recent Iraqi battles against ISIS in 2014 and 2015 resulted in the destruction or severe damage to several refineries' infrastructure. This, along with other factors, has led to the release and accumulation of a wide range of hazardous chemicals into the environment, for instance, polycyclic aromatic hydrocarbons (PAH). Thus, for the first time, a comprehensive 16 PAHs measurements campaign over the course of six months near the oil refineries along the Tigris River and its estuaries was investigated. The 16 PAHs concentrations in surface water and the sediments for the following oil refineries: Baiji, Kirkuk, Al-Siniyah, Qayyarah, Al-Kasak, Daura, South Refineries Company, and Maysan were examined. The overall findings indicated that the 16 PAHs concentrations ranged from 567.8 to 3750.7 ng/L for water and 5619.2–12795.0 ng/g for sediment. Water samples in South Refineries Company recorded the highest PAH concentrations while Baiji oil refinery registered the highest PAH concentrations in the sediment samples. The percentages of high molecular weight PAH (5–6 rings) in water and sediment samples were the highest, ranging from 49.41% to 81.67% and from 39.06% to 89.39% of total PAH for water and sediment, respectively. The majority of 16 PAHs measured in water and sediment samples of the Tigris River were derived from pyrogenic sources. Based on sediment quality guidelines (SQGs), most sites showed a possible effect range with occasional biological effects of most of the PAH concentrations in all sediments’ samples. The calculated incremental lifetime cancer risk (ILCR) value was high risk with adverse health effects, including cancer.

Funding Information: First and foremost, we are grateful to the anonymous reviewers for improving the paper's quality. The authors acknowledge the support in the form of various facilities provided by Aalto University, Finland and Liverpool John Moores University, UK. We also appreciate the facilities provided by the Environmental Research and Studies Center (ERSC), University of Babylon, Iraq. This article represents the views or opinions of its authors. Funding Information: The ÚNKP-22-3-I-PE-12 New National Excellence Program of the Ministry for Culture and Innovation from the source of the National Research, Development and Innovation Fund supported this research. The study was partially supported by the Stipendium Hungaricum, and the Environmental Research and Studies Center, University of Babylon. Publisher Copyright: © 2022 The Authors In recent years, enzymatic remediation/biocatalysis has gained prominence for the bioremediation of recalcitrant chemicals. Laccase is one of the commonly investigated enzymes for bioremediation applications. There is a growing interest in immobilizing this enzyme onto adsorbents for achieving high pollutant removal through simultaneous adsorption and biodegradation. Due to the influence of the biomolecule-support interface on laccase activity and stability, it is crucial to functionalize the solid carrier prior to immobilization. Date stone (PDS), as an eco-friendly, low-cost, and effective natural adsorbent, was utilized as a carrier for laccase (fungus Trametes versicolor). After activating PDS through chemical treatments, the surface area increased by thirty-six-fold, and carbonyl groups became more prominent. Batch experiments were carried out for ketoprofen and aspirin biodegradation in aqueous solutions. After six cycles, the laccase maintained 54% of its original activity confirmed by oxidation tests of 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS). In addition, the storage, pH, and thermal stability of immobilized laccase on functionalized date stone (LFPDS) were found to be superior to that of free laccase, demonstrating its potential for ongoing applications. In the aqueous batch mode, this immobilized laccase system was used to degrade 25 mg L−1 of ketoprofen and aspirin, resulting in almost complete removal within 4 h of treatment. This study reveals that agricultural wastes such as date stone can successfully be valorized through simple activation techniques, and the final product can be used as an adsorbent and substrate for immobilization enzyme. The high efficiency of the LFPDS in removing ketoprofen and aspirin highlights the potential of this technology for removing pharmaceuticals and merits its continued development.

Publisher Copyright: © 2022 The Authors Adsorption is a well known effective technology for water treatment. Although limited capacities of adsorbents and regeneration issues are two common challenges. This study proposed and tested innovative approaches for improving adsorption/desorption of biochar made from macadamia nutshell (MBC). These approaches are capacitive deionization (CDI) and degaussing (full process detailed in methods), for the respective enhancement of adsorption and desorption of MBC. Nitrate was used as a model contaminant. It was found that CDI could extend the saturation time of MBC by increasing the bed specific throughput by 10 fold. Modeling of the breakthrough curves showed that the modified dose-response model fits well the experimental data. The regeneration of MBC with degaussing and deionized water backwash was compared with conventional tap and deionized water backwash. Degaussing increased the maximum nitrate recovery for deionized water from 50% to 73%. In comparison, the maximum nitrate recovery with tap water was 23%. The degaussing improvement of nitrate desorption holds for only the first 60 min. The obtained charge efficiency for MBC-CDI was slightly higher than literature values for the same applied voltage (78,6%). The degaussing system was also proven to be efficient with energy consumption of 43,7 J/mmol of NO3−. The possible mechanism behind degaussing improvement of nitrate desorption is the removal of the static charges on nitrate ion hydration. The regenerated MBC with degaussing and deionized water was tested with CDI for nitrate adsorption and compared to fresh MBC. The regenerated MBC-CDI exhibited better nitrate adsorption than fresh MBC for two cycles.

Membrane fouling remains a major obstacle to ultrafiltration. Due to their effectiveness and minimal energy demand, membranes have been extensively employed in water treatment. To improve the antifouling property of the PVDF membrane, a composite ultrafiltration membrane was created employing the in-situ embedment approach throughout the phase inversion process and utilizing a new 2D material, MAX phase Ti3ALC2. The membranes were described using FTIR (Fourier transform infrared spectroscopy), EDS (energy dispersive spectroscopy), CA (water contact angle), and porosity measurements. Additionally, atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), and energy dispersive spectroscopy (EDS) were employed. Standard flux and rejection tests were applied to study the produced membranes’ performance. Adding Ti3ALC2 reduced composite membranes’ surface roughness and hydrophobicity compared to the pristine membrane. Porosity and membrane pore size increased with the addition up to 0.3% w/v, which decreased as the additive percentage increased. The mixed matric membrane with 0.7% w/v of Ti3ALC2 (M7) had the lowest CA. The alteration in the membranes’ properties reflected well on their performance. The membrane with the highest porosity (0.1% w/v of Ti3ALC2, M1) achieved the highest pure water and protein solution fluxes of 182.5 and 148.7. The most hydrophilic membrane (M7) recorded the highest protein rejection and flux recovery ratio of 90.6, which was much higher than that of the pristine membrane, 26.2. MAX phase Ti3ALC2 is a potential material for antifouling membrane modification because of its protein permeability, improved water permeability, and outstanding antifouling characteristics.

The concerns regarding the reactive nitrogen levels exceeding the planetary limits are well documented in the literature. A large portion of anthropogenic nitrogen ends in wastewater. Nitrogen removal in typical wastewater treatment processes consumes a considerable amount of energy. Nitrogen recovery can help in saving energy and meeting the regulatory discharge limits. This has motivated researchers and industry professionals alike to devise effective nitrogen recovery systems. Membrane technologies form a fundamental part of these systems. This work presents a thorough overview of the subject using scientometric analysis and presents an evaluation of membrane technologies guided by literature findings. The focus of nitrogen recovery research has shifted over time from nutrient concentration to the production of marketable products using improved membrane materials and designs. A practical approach for selecting hybrid systems based on the recovery goals has been proposed. A comparison between membrane technologies in terms of energy requirements, recovery efficiency, and process scale showed that gas permeable membrane (GPM) and its combination with other technologies are the most promising recovery techniques and they merit further industry attention and investment. Recommendations for potential future search trends based on industry and end users’ needs have also been proposed.

Funding Information: We thank the University of Technology Sydney (UTS) for a PhD Scholarship to support this research project. Publisher Copyright: © 2022 The Author(s) Perfluorooctanoic acid (PFOA) is a persistent, nonbiodegradable environmental pollutant progressively becoming more problematic. Due to its ubiquitous use, PFOA is one of the PFAS chemicals frequently detected in the environment. This study assessed electrokinetic (EK) technology as an in-situ remediation procedure to remove PFOA from kaolinite as a model soil. In this study, a 100 mg/kg of PFOA/kaolinite mixture was used, and the effectiveness of the unenhanced EK was compared with the surfactant-enhanced EK experiments with SDS, NaC, and Tween80. 5% (w/w) surfactants were added to the cathode in the EK experiments of one and two weeks long. The study evaluated the impacts of processing time and electric current on the EK performance. Electroosmosis and electromigration mechanisms affected PFOA transport in soil, causing PFOA to accumulate in the middle of the soil. However, the minimal accumulation of PFOA in the cathode region suggests that electromigration was the main transport mechanism. In a one-week EK experiment, the PFOA removal efficiency in the unenhanced EK process was 14.49% at 10 mA and 19.00% at 20 mA, while in surfactant enhanced EK, it was 17.67% at 10 mA and reached 32.66% at 20 mA. The PFOA removal in surfactant enhanced EK reached 75.58% in the two weeks EK experiments carried out at 20 mA. The NaC-EK experiment exhibited the highest PFOA removal, followed by the SDS-EK experiment and TW80-EK experiment. The outcomes show the feasibility of removing PFAS from contaminated soil using the surfactant-enhanced EK technique.

Funding Information: First and foremost, we are grateful to the anonymous reviewers for improving the paper quality. Thank Ahmed Al-Azawi, Mostafa Kadhem Al-Baaiti and Liath M. Al-Musawy from the ministry of education for their help in collecting the data. Additionally, thank Basheer Khalid, Ali Jaber Oudah and Ghazwan Hussein Hamza for their effort in logistic support. The views in this manuscript are those of the authors, and they do not reflect those of other agencies. Additionally, this study has not received any specific grants. We also declare no conflict of interest. Publisher Copyright: © 2022 Elsevier Ltd Particulate matter (PM) is a major indicator of urban air quality deterioration due to its impact on human health, atmospheric visibility and climate change. However, sufficient data on personal exposure to air pollution is still rare or unavailable in developing countries such as Iraq. Thus, this paper investigated the personal exposure and inhalation doses of PM1 and PM2.5 in Al-Hillah city, Iraq, for four common motorized transportation modes, namely open windows car, closed window car, bus, and motorbike. A portable monitoring device was used to collect the data during morning and afternoon hours in two main streets in the city. A t-test examination of the obtained results showed that the mean exposure concentration for both PM2.5 and PM1 were significantly different in the two streets form most of the transportation modes. The difference in the means of the measured PM1 and PM2.5 in the morning and afternoon trips were statistically significant for all the transportation modes except for bus in 60 street. This highlights the special and temporal variation of air pollution in the city. This is largely due the deteriorated infrastructure and lack of control policies in the city. Overall, PM2.5 and PM1 measured exposure concentrations were higher in the morning trips than in the afternoon ones. Regardless of the time or place of measurements, closed windows cars always had the lowest exposure concentrations to PM1 and PM2.5. The alarming observation in this study was the high levels of PM1 and PM2.5 that exceeded the recommended WHO limits, and were higher than the reported concentrations in the world bank database. The study findings present preliminary data on personal exposure concentrations and inhalation doses for travelers in Al-Hillah city, which can be utilized for global studies of air contamination in countries in similar situations as Iraq and for developing local control strategies.

The research reported in this paper was supported by University of Southern Queensland, and Ministry of Higher Education and Scientific Research (Iraq). We would also like to thank our industry partners for their help and assistance. In particular, we would like to acknowledge the technical support of the Scarab Co. staff and provision of membranes from Donaldson filtration.

Publisher Copyright: © 2021 Elsevier Ltd Membrane separation is widely used in wastewater treatment and desalination due to its high performance and ability to handle feed solutions of different qualities. Despite vast history of success, membrane fouling remains a major system deficiency that imposes substantial process limitations by reducing permeate production and increasing energy demand. Besides, chemical cleaning-in-place (CIP) adversely affects membrane integrity and generates an extra waste stream. Ultrasound (US) is a relatively new cleaning technique that improves process performance by mitigating fouling accumulation at a membrane surface and improving permeate flux by promoting mass and heat transfer. US-assisted membrane processes is an efficient method for fouling reduction and significant flux improvement. This study comprehensively reviews US applications in pressure-, thermally- and osmotic-driven membrane technologies and their impact on process performance. It also explores the impact of US operating conditions on membrane separation properties and how these parameters can be tuned to achieve the desirable outcome. To date, the application of US in membrane technologies is limited to laboratory tests. In the authors' opinion, there is a niche market for US-assisted membrane technology in heavily contaminated water such as wastewater and brine. After critical analysis of the literature, we found that there are still several aspects of the process need to be scrutinized carefully to make an adequate evaluation of its feasibility on an industrial scale. The most urgent one is the techno-economic evaluation of the technology based on large-scale and long-term tests. The study proposed a set of recommendations for future research directions of US applications in membrane technologies.

Landfill leachate is considered to be a potential source for nutrient recovery due to high ammonia concentration. However, it contains concerning pollutants such as metals and micropollutants in high levels. The coagulation-flocculation process is commonly used as a pretreatment technique to remove such pollutants. Plant-based materials have recently been explored as an alternative for conventional coagulants as the latter leave residuals that require further treatment. The use of natural coagulants for nutrient recovery purposes has not been investigated previously. This study evaluated the effectiveness of tannin-based product named HTH to improve landfill leachate quality to suite the requirements for nitrogen recovery using membrane contactor technology. The optimal combination of dosage and pH was determined using Response Surface Methodology (RSM). The parameters selected to evaluate the treatment were total nitrogen, total phosphorus, total organic carbon, and ammonia. The obtained optimized combination of dosage and pH were 11.1 mL/L and 7.3, respectively. This combination resulted in respective removal of TP, TOC and TN of 47%, 15%, and 4%, while NH3‒N increased by 20%. The potency of the treatment for removing micropollutants and metals was evaluated. Highest metals removal was attained for Fe, Ti, Cr, Al, Ba and V, while other metals were removed in smaller percentages. Decent removal of cationic surfactants, phenols and pharmaceuticals such as 5-methylbenzotriazole, ibuprofen, carbamazepine, and metoprolol was also achieved with the treatment. The results of this study suggest that tannin-based materials are effective coagulants for treating landfill leachate with the goal of preparing it for nitrogen recovery.

This study investigates the efficiency of low-power ultrasound in the range of 3.5–30.0 W to improve permeate flux and alleviate membrane fouling in an air–gap membrane distillation (AGMD) system. Natural groundwater and reverse osmosis (RO) reject water were fed into the AGMD system on which fouling experiments were conducted with hydrophobic polyvinylidene fluoride (PVDF) membrane. After 35 h of AGMD system operation with groundwater and RO reject water, fouling caused the permeate flux to decrease by 30% and 40% respectively. Concentration polarization, intermediate pore blocking, and cake filtration appear to be the main reasons for flux decline with both feedwater types. Ultrasound application for a short period of 15 min resulted in flux improvement by as high as 400% and 250% for RO reject and groundwater, respectively. Modelling of the heat and mass transfers showed that the flux increase was mainly due to membrane permeability improvements under ultrasonic vibration. Fouling visualisation using Scanning Electron Microscopy revealed that ultrasound effectively removed membrane fouling without compromising the membrane's structure. Importantly, permeate flux improvements with targeted low-power ultrasound appears to be proportionally higher than those of high-power ultrasound applied to the whole system, on a flux improvement per ultrasound W/m2 basis.

The interest in using natural coagulants for wastewater treatment has increased in recent years due to the environmental and health problems associated with the use of traditional coagulants. In this study, starch-based coagulants were tested to treat reject water produced by the dewatering of mesophilic digester sludge at the Viikinmaki wastewater treatment plant (WWTP) in Finland. The goal of this treatment is to prepare the stream for the nitrogen recovery process with membrane contactor technology. Screening tests showed that PrimePHASE 3545 was the best coagulant, and the effective dosage and pH ranges were 10–20 ml/l of the 25% diluted starch and 8–10 pH values, respectively. The process was optimized using Response Surface Methodology (RSM). The best dosage and pH combination generated by RSM was 14.1 ml/l and 9.1, respectively. In these conditions, TN, TP, TOC, SS and VSS removal percentages were 18 ± 0.57%, 80 ± 0.99%, 28 ± 1.19%, 90 ± 3.37%, and 89 ± 2.35%, respectively. However, NH3-N concentration increased by 20 ± 1.7%, mainly due to pH increase. These results held true when tested on a pilot scale at Viikinmaki WWTP in a continuous process. The sludge produced with natural coagulant was found to be of a better quality compared to that of conventional coagulants.

The removal of inorganic arsenic (As) species from water using bone char pyrolyzed at 900 °C was investigated. Results revealed that the Sips model resulted in the best As(III) experimental data fit, while As(V) data were best represented by the Langmuir model. The adsorption rate and mechanisms of both As species were investigated using kinetic and diffusional models, respectively. At low As(III) and As(V) concentrations of 0.5 and 2.5 mg/L, the removal was due to intra-particle interactions and pore diffusion following Pseudo-first-order kinetics. However, at higher concentrations of 5 and 10 mg/L, the pore diffusion mechanism was ineffective, and the adsorption was best described by Pseudo-second-order and Elovich models. The goodness of the fit of linearized and nonlinear forms of all models against experimental data was thoroughly tested using error function analysis. Nonlinear regressions produced lower error values, so they were utilized to calculate the parameters of the models. The changes in bone char surface chemistry were examined using FTIR and Energy-dispersive X-ray spectroscopy (EDS). Arsenic oxide and complexes with metals were the confirmed immobilized forms of As on the bone-char surface. To the authors’ knowledge, this study is the first attempt at As(III) adsorption analysis using bone char.

The application of pulsed mode ultrasound (PMU) as a pre-treatment for alum coagulation was investigated at various alum dosages and pH levels. The effects of the treatments on turbidity and dissolved organic carbon (DOC) removal and residual Al were evaluated. Response surface methodology (RSM) was utilized to optimize the operating conditions of the applied treatments. The results showed that PMU pre-treatment increased turbidity and DOC removal percentages from maximum of 96.6% and 43% to 98.8% and 52%, respectively. It also helped decrease the minimum residual Al from 0.100 to 0.094 ppm. The multiple response optimization was carried out using the desirability function. A desirability value of >0.97 estimated respective turbidity removal, DOC removal and Al residual of 89.24%, 45.66% and ∼0.1 ppm for coagulation (control) and 90.61%, >55% and ∼0 for coagulation preceded by PMU. These figures were validated via confirmatory experiments. PMU pre-treatment increased total coliform removal from 80% to >98% and decreased trihalomethane formation potential (THMFP) from 250 to 200 ppb CH3Cl. Additionally, PMU application prior to coagulation improved the settleability of sludge due to the degassing effects. The results of this study confirms that PMU pre-treatment can significantly improve coagulation performance.

In this study, a newly developed nitrogen (N) and phosphorus (P) recovery process using a membrane contactor termed NPHarvest was tested with different liquid waste streams in large-scale trials. Ammonia was captured in ammonium sulfate form using a hydrophobic membrane, while phosphorus was precipitated as sludge using alkali precipitation and coagulation processes. The tested streams were selected to cover the potential liquid waste streams for nitrogen recovery and included two different mesophilic digester reject waters, landfill leachate, and separately collected urine. The NPHarvest pilot was tested with hydraulic loads in the range of 12–133 L/h. Nitrogen recovery efficiency reached a maximum of 92.5% with the reject water of mesophilic digester and a maximum ammonia flux of 481.1 mg/L.h was obtained with a urine stream. A mass transfer coefficient was calculated for the four tested wastewater streams using two different approaches, resulting in two value ranges in the order of 10-3 and 10-7 m/s. It was found that the mass transfer coefficient decreased with increase in the initial nitrogen concentration. The recovery of phosphorus varied between 79% and 97%. The quality of ammonium sulfate was evaluated by employing comprehensive tests that included vegetative cells and coliphages, harmful metals, and organic micropollutant measurements. These measurements confirmed that ammonium sulfate meets the Finnish legislation requirements for agricultural use. The use of a diluted acid wash was proven to be sufficient for maintaining membrane surface properties and was confirmed by the observed insignificant loss of hydrophobicity and the mild development of fouling. Finally, the competitiveness of NPHarvest compared to existing processes was confirmed through a detailed cost analysis.

Applying biochar (BC) to broad acre crops is an effective way to sequester carbon while improving soil fertility and reducing nutrient leaching. Adopting a similar approach in a hydroponic environment, BC may enhance nutrient availability and reduce natural fluctuations in the nutrient solution. This study monitored the effect of BC addition to peatmoss growth media with ratios of 0%, 5%, 25% and 50% on pH, electrical conductivity (EC) and macronutrient retention, over 15 days using hydroponic nutrient solution controls. Deionised water was used to measure nutrient releases in the closed loop hydroponic system, showing that biochar increased pH level in both retention and release stages. As expected, the pH increased by a maximum of 1.5 units with the highest biochar to growth media ratio due to the natural liming nature of the BC. The EC was also affected, as BC increased in the media EC reduced. With regards to retention of nutrients, BC recovered nitrate, phosphate, calcium and sulphate but did not affect magnesium. Potassium levels increased in solution with increasing BC ratio. In terms of outcomes relevant to global agriculture, the results show that the same level of production can nominally be obtained with around half the nutrient requirements.

This study examined arsenite [As(III)], arsenate [As(V)] and fluoride (F−) removal potential of bone char produced from sheep (Ovis aries) bone waste. Pyrolysis conditions tested were in the 500 °C–900 °C range, for a holding time of 1 or 2 h, with or without N2 gas purging. Previous bone char studies mainly focused on either low or high temperature range with limited information provided on As(III) removal. This study aims to address these gaps and provide insights into the effect of pyrolysis conditions on bone char sorption capacity. A range of advanced chemical analyses were employed to track the change in bone char properties. As pyrolysis temperature and holding time increased, the resulting pH, surface charge, surface roughness, crystallinity, pore size and CEC all increased, accompanied by a decrease in the acidic functional groups and surface area. Pyrolysis temperature was a key parameter, showing improvement in the removal of both As(III) and As(V) as pyrolysis temperature was increased, while As(V) removal was higher than As(III) removal overall. F− removal displayed an inverse relationship with increasing pyrolysis temperature. Bone char prepared at 500 °C released significantly more dissolved organic carbon (DOC) then those prepared at a higher temperature. The bone protein is believed to be a major factor. The predominant removal mechanisms for As were surface complexation, precipitation and interaction with nitrogenous functional groups. Whereas F− removal was mainly influenced by interaction with oxygen functional groups and electrostatic interaction. This study recommends that the bone char pyrolysis temperature used for As and F− removal are 900 °C and 650 °C, respectively.

Air Gap Membrane distillation (AGMD) is a thermally driven separation process capable of treating challenging water types, but its low productivity is a major drawback. Membrane fouling is a common problem in many membrane treatment systems, which exacerbates AGMD’s low overall productivity. In this study, we investigated the direct application of low-power ultrasound (8–23 W), as an in-line cleaning and performance boosting technique for AGMD. Two different highly saline feedwaters, namely natural groundwater (3970 μS/cm) and RO reject stream water (12760 μS/cm) were treated using Polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) membranes. Theoretical calculations and experimental investigations are presented, showing that the applied ultrasonic power range only produced acoustic streaming effects that enhanced cleaning and mass transfer. Attenuated Total Reflection Fourier-Transform Infrared Spectroscopy (ATR FT-IR) analysis showed that ultrasound was capable of effectively removing silica and calcium scaling. Ultrasound application on a fouled membrane resulted in a 100% increase in the permeate flux. Cleaning effects accounted for around 30–50% of this increase and the remainder was attributed to mass transfer improvements. Contaminant rejection percentages were consistently high for all treatments (>99%), indicating that ultrasound did not deteriorate the membrane structure. Scanning Electron Microscopy (SEM) analysis of the membrane surface was used to confirm this observation. The images of the membrane surface demonstrated that ultrasound successfully cleaned the previously fouled membrane, with no signs of structural damage. The results of this study highlight the efficient and effective application of direct low power ultrasound for improving AGMD performance.

Arsenic (As) is an emerging contaminant on a global scale posing threat to environmental and human health. The relatively brief history of the applications of biochar and bone char has mapped the endeavors to remove As from water to a considerable extent. This critical review attempts to provide a comprehensive overview for the first time on the potential of bio- and bone-char in the immobilization of inorganic As in water. It seeks to offer a rational assessment of what is existing and what needs to be done in future research as an implication for As toxicity of human health risks through acute and chronic exposure to As contaminated water. Bio- and bone-char are recognized as promising alternatives to activated carbon due to their lower production and activation cost. The surface modification via chemical methods has been adopted to improve the adsorption capacity for anionic As species. Surface complexation, ion exchange, precipitation and electrostatic interactions are the main mechanisms involved in the adsorption of As onto the char surface. However, arsenic-bio-bone char interactions along with their chemical bonding for the removal of As in aqueous solution is still a subject of debate. Hence, the proposed mechanisms need to be scrutinized further using advanced analytical techniques such as synchrotron-based X-ray. Moving this technology from laboratory phase to field scale applications is an urgent necessity in order to establish a sustainable As mitigation in drinking water on a global scale. Keywords: Inorganic arsenic, Engineered biochar, Bone char, Surface modification, Sorption capacity, Immobilization

The application of pulsed ultrasound for DOC removal from natural water samples has been thoroughly investigated in this work. Natural water samples were treated with ultrasound at power levels of 48 and 84 W with treatment times of 5 and 15 min. Chemical fractionation was conducted for both untreated and treated samples to clearly identify the change in DOC structure caused by ultrasonic treatments. Statistical analyses applying 2(3) factorial design were performed to study the behaviour of the response (i.e. DOC removal) under different operating conditions. Overall, ultrasonic treatments resulted in DOC removal of 7-15% depending on the applied operating conditions. The treated water had high microbial loading that interfered with DOC removal due primarily to the release of microbial products when exposed to ultrasound. Pulse ultrasound was found to be more effective than the continuous mode for DOC removal at the same effective power level. A regression model was developed and tested for DOC removal prediction. The model was adequate in predicting DOC removal with a maximum deviation from the experimental data of

Chemical fractionation is a powerful tool for unravelling the reasons behind water treatment problems such as the formation of disinfection by-products (DBPs). This technique can however be costly and time-consuming. Hence, exploring quick affordable surrogate measurements to this technique is of great importance for water treatment operators. In this study, the correlations between aquatic carbon fractions and single wavelength and UV ratios of A254, A280, A254/A204, A250/A365 and A254/A436 were examined for seven water bodies located in South-east Queensland, Australia. It was observed that A254/A204 has a strong and significant correlation with hydrophobic/hydrophilic ratio (R2 = 0.984). A250/A365 exhibited a weak but significant correlation with the same fraction ratio (R2 = 0.687) suggesting that the chemical fractions cannot be assumed of a certain molecular size. A254/A436 had a weak and insignificant correlation with carbon fractions (R2 = 0.0506). The hydrophobic fraction of the seven wat...

Obtaining accurate power characteristics of ultrasonic treatment systems is an important step towards their industrial scalability. Calorimetric measurements are most commonly used for quantifying the dissipated ultrasonic power. However, accuracy of these measurements is affected by various heat losses, especially when working at high power densities. In this work, electrical power measurements were conducted at all locations in the piezoelectric ultrasonic system equipped with 1/2 inch and 3/4 inch probes. A set of heat transfer calculations were developed to estimate the convection heat losses from the reaction solution. Chemical dosimeters represented by the oxidation of potassium iodide, Fricke solution and 4-nitrophenol were used to chemically correlate the effect of various electrical amplitudes and treatment regimes. This allowed estimation of sonochemical-efficiency (SE) and energy conversion (XUS) of the ultrasonic system. Results of this study showed overall conversion efficiencies of 60-70%. This correlated well with the chemical dosimeter yield curves of both organic and inorganic aqueous solutions. All dosimeters showed bubble shielding and coalescence effects at higher ultrasonic power levels, less pronounced for the 1/2 inch probe case. SE and XUS values in the range of 10-10 mol/J and 10-3 J/J respectively confirmed that conversion of ultrasonic power to chemical yield declined with amplitude.

The deterioration of surface water quality due to extreme weather events and increasing human activities has exacerbated the common problems in drinking water production such as filtration fouling and DPBs formation. This in turn has urged for exploring alternative methods for the traditional treatment methods that are able to improve the removal of contaminants with minimal impact on environment and human health. In this study, the application of pulsed and continuous ultrasound for improving the quality of natural water with fresh natural organic matter (NOM) mainly driven from vegetation has been evaluated. The evaluation was performed using cost-effective and quick measurements such as specific UV–vis absorbance, CODMn, alkalinity and conductivity. The changes in the characteristics of NOM induced by ultrasound were used to develop a framework for evaluating ultrasound performance in improving conventional surface water treatment processes and to identify the best fit of ultrasound within the ...

This review article addresses wastewater treatment methods in the red meat processing industry. The focus is on conventional chemicals currently in use for abattoir wastewater treatment and energy related aspects. In addition, this article discusses the use of cleaning and sanitizing agents at the meat processing facilities and their effect on decision making in regard to selecting the treatment methods. This study shows that cleaning chemicals are currently used at a concentration of 2% to 3% which will further be diluted with the bulk wastewater. For example, for an abattoir that produces 3500 m3/day wastewater and uses around 200 L (3%) acid and alkaline chemicals, the final concentration of these chemical will be around 0.00017%. For this reason, the effects of these chemicals on the treatment method and the environment are very limited. Chemical treatment is highly efficient in removing soluble and colloidal particles from the red meat processing industry wastewater. Actually, it is shown that, if chemical treatment has been applied, then biological treatment can only be included for the treatment of the solid waste by-product and/or for production of bioenergy. Chemical treatment is recommended in all cases and especially when the wastewater is required to be reused or released to water streams. This study also shows that energy consumption for chemical treatment units is insignificant while efficient compared to other physical or biological units. A combination of a main (ferric chloride) and an aid coagulant has shown to be efficient and cost-effective in treating abattoir wastewater. The cost of using this combination per cubic meter wastewater treated is 0.055 USD/m3 compared to 0.11 USD/m3 for alum and the amount of sludge produced is 77% less than that produced by alum. In addition, the residues of these chemicals in the wastewater and the sludge have a positive or no impact on biological processes. Energy consumption from a small wastewater treatment plant (WWTP) installed to recycle wastewater for a meet facility can be around $500,000.

This paper reviews various non-conventional techniques for microorganism disruption. Microorganism disruption plays a pivotal role in various agricultural applications such as disinfection of irrigation water, processing of crops and livestock products and the newly emerging area of bioenergy production for agricultural uses. Methods of treatment to destroy microorganisms for the purposes of disinfection or extraction of bio-products can be generally categorized as either thermal treatment methods or non-thermal treatment methods. The thermal methods for microbial disruption are not favorable in many applications such as food processing and water treatment due to its negative impact on product quality and process performance. The discussion of thermal methods for microorganism disruption will not be included in this review. Non-thermal treatments are divided into two groups; chemical and physical treatments. Owing to the concerns of the health organisations with regards to the use of chemical methods for microorganism disruption, the recent research efforts have been directed towards exploring alternative physical methods for rupturing microorganisms. The common alternative physical methods for microorganism disruption include mechanical and non-mechanical treatments. This paper discusses in details the use of the common mechanical treatments for cell disintegration. Such methods include ultrasound, shock wave, High Pressure Homogenization (HPH), Hydrodynamic Cavitation (HC), shear stress, bead milling and micro-fluidizer. The application of the non-mechanical methods for microbial disruption such as electrical treatment, non-thermal plasma, Ultra-Violet (UV), non-conventional chemical methods and some other treatments are also briefly addressed in this paper. Due to the importance of the mechanical methods in the current cell disruption research, more attention is directed to these methods in this work.

The reverse osmosis (RO) technology offers a solution for the shortage of pristine water resources worldwide, through its capacity on treating all water kinds such as seawater, wastewater, ground water and surface water. The main concern in using RO technology for water treatment is fouling problems, and in particular biofouling. Biofouling negatively affects the quality of RO product and renders RO a costly technology for water treatment. The key solution to reduce the risk of biofouling in RO system lies in understanding the process of biofouling formation, choosing an adequate biofilm monitoring technique and applying effective biofouling control treatment for the RO membrane system. In this paper, the mechanisms of microbial adhesion to RO membrane are illustrated along with the key factors that influence the microbial adhesion process. In addition to that, the common strategies for biofilm monitoring in water flow systems are reviewed with highlighting applications, advantages and disadvantages of each strategy. The common biofouling control methods for reducing the formation of biofouling in the RO system are also presented in this paper. The application of the environmentally friendly physical disinfection techniques for biofouling control in the RO membrane system is suggested in this paper.