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A series of novel adsorbents composed of cellulose (CL) with Ca/Al layered double hydroxide (CCxA; where x represent the Ca/Al molar ratio) were prepared for the adsorption of antimony (Sb(V)) and fluoride (F−) ions from aqueous solutions. The CCxA was characterized by Fourier-transform infrared spectroscopy (FTIR), Brunauer–Emmett–Teller (BET), elemental analysis (CHNS/O), thermogravimetric analysis (TGA-DTA), zeta potential, X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) analysis. The effects of varying parameters such as dose, pH, contact time, temperature and initial concentration on the adsorption process were investigated. According to the obtained results, the adsorption processes were described by a pseudo-second-order kinetic model. Langmuir adsorption isotherm model provided the best fit for the experimental data and was used to describe isotherm constants. The maximum adsorption capacity was found to be 77.2 and 63.1 mg/g for Sb(V) and F−, respectively by CC3A (experimental conditions: pH 5.5, time 60 min, dose 15 mg/10 mL, temperature 298 K). The CC3A nanocomposite was able to reduce the Sb(V) and F− ions concentration in synthetic solution to lower than 6 μg/L and 1.5 mg/L, respectively, which are maximum contaminant levels of these elements in drinking water according to WHO guidelines.

Laccase-catalysed degradation is a promising technology for the degradation of trace organic contaminants (TrOCs). However, depending on their physicochemical properties (e.g., chemical structures), non-phenolic TrOCs appear to be resistant to laccase-catalysed degradation, thus requiring an additional treatment process. In this study, the performance of an integrated laccase and persulfate (PS) mediated oxidation process was explored and elucidated for the first time. Compared to that achieved during treatment with laccase alone, the addition of PS at 1–10 mM concentration into batch enzymatic bioreactors showed concentration-dependent improvement in the degradation of the five TrOCs selected, namely diclofenac, sulfamethoxazole, carbamazepine, bisphenol A and oxybenzone. The results obtained from a series of batch tests also confirmed that the structural components (e.g., carbohydrate moieties in the enzyme) as well as the possibility of PS acting as a final acceptor of electrons from the type II and type III active sites of laccase may have led to PS activation. A continuous treatment system was developed by integrating a nanofiltration (NF) membrane with the laccase/PS process (NF-MBRlaccase/PS), which achieved TrOC-specific degradation. Importantly, the degradation of non-phenolic TrOCs (diclofenac, sulfamethoxazole and carbamazepine) further improved by 10 to 65% in the NF-MBRlaccase/PS system. This improvement could be attributed to: (i) the prolonged contact time between laccase/PS and TrOCs, which was possible due to their complete retention by the NF membrane; and (ii) retention of oxidative cross coupling agents or secondary radicals enhancing TrOC degradation. The NF membrane not only retained the moderately degraded carbamazepine and sulfamethoxazole effectively but also effectively removed toxic transformation products and residual estrogenicity of the final effluent as evaluated by cytotoxicity and estrogenicity assays, respectively. These observations indicate the significance of the high retention membrane in the NF-MBRlaccase/PS system for producing high quality permeate suitable for disposal and potentially for water reuse applications.

Phosphorus is a critical non-renewable mineral essential for sustainable crop production. However, it is a primary cause of eutrophication in natural water bodies. Hence, a pragmatic approach that allows wastewater treatment plants to efficiently recover phosphorus from wastewater is needed. In this study, we investigated phosphorus recovery from municipal wastewater using an industrial waste product (steelmaking slag) as an adsorbent to selectively separate phosphorus from wastewater before its concentration by the forward osmosis (FO) process. Phosphorus adsorbed on slag was extracted, thereby regenerating the adsorbent medium. The resulting phosphorus-rich solution was further enriched by FO prior to chemical precipitation for phosphorus recovery. Batch test results showed that the equilibrium of phosphorus sorption on the slag medium was achieved within 45 min with an adsorption capacity of 3.8 mg g−1. In continuous-flow column tests, the slag exhibited a stable phosphorus removal efficiency of 82% from wastewater, following which approximately 88% of the phosphate could be extracted from the adsorbent medium. When the phosphorus-rich solution extracted from the adsorbent was passed through the FO membrane, FO could retain 98% of the phosphate. However, the water flux through the FO membrane declined gradually to approximately 20% of the initial value at a water recovery of 90%, which could be attributed to the increasingly concentrated feed solution. The enrichment of phosphate in the concentrated feed by the FO process provided a favorable condition for spontaneous precipitation of amorphous calcium phosphate. This study demonstrates that the proposed combined adsorption–FO process can effectively remove, and thus recover, phosphorus from municipal wastewater.

Groundwater is the dominant source of freshwater in many countries around the globe, and the deterioration in its quality by contaminants originating from anthropogenic sources raises serious concern. In this study, a scenario where groundwater is contaminated by acid mine drainage (AMD) from mining activities and/or sewage was envisaged, and the performance of a direct contact membrane distillation (DCMD) system was investigated comprehensively for different compositions of the AMD- and sewage-impacted groundwater. Regardless of the composition, MD membrane achieved 98-100% removal of metals and bulk organics, while the removal of the selected micropollutants ranged between 80 and 100%. Effective retention of contaminants by the MD led to their accumulation over time, which affected the hydraulic performance of the MD membrane by reducing the permeate flux by 29-76%. When persulfate (PS)-mediated oxidation process was integrated with the DCMD, degradation of bulk organics (50-71%) and micropollutants (50-100%) by PS reduced their accumulation. Characterisation of the fouling layer revealed the occurrence of membrane scaling that was mainly due to the deposition of iron oxide or oxyhydroxide precipitates. For an identical composition of the AMD- and sewage-impacted groundwater, flux decline was 10% less in PS-assisted DCMD as compared to that in the standalone DCMD. However, this did not prevent the formation of iron oxide scales on MD membrane during the operation of PS-assisted DCMD. This study demonstrates the long-term performance of a standalone and PS-assisted DCMD operated in continuous-flow mode to treat AMD- and sewage-impacted groundwater for the first time.

The presence of carcinogenic N-nitrosamines and dissolved organic matter (DOM) in freshwater is a significant concern from the perspective of public health and drinking water treatment plant operation. This study investigated the N-nitrosamines concentration and their precursors' distributions, and DOM composition in four reservoirs located in a southern city of China. A total of 22 renowned precursors were identified. Precursors from industrial and pharmaceutical origins were found to be dominant in all reservoirs; however, traces of pesticide-based precursors, i.e. pirimicarb and cycluron were also found. The distribution of nine N-nitrosamines was substantially different among the reservoirs. N-Nitrosodibutylamine (NDBA), N-Nitrosopiperidine (NPIP), N-Nitrosodimethylamine (NDMA), and N-Nitrosopyrrolidine (NPYR) were abundantly present in all reservoirs. Most of N-nitrosamines except NDMA and N-nitrosodiethylamine (NDEA) were far below the generally accepted cancer risk of 10-6, and NDMA/NDEA were found close to the risk level (10-6). Anthropogenic DOM was dominant in three reservoirs as depicted by a higher biological index (BIX) than the humification index (HIX). By the principle component analysis, BIX appeared as an indicator of N-nitrosamines (except NDEA and NPIP). A strong and direct relationship was observed between the NDMA-formation potential (FP) and concentration of total N-nitrosamines (∑NA), and BIX. These results confirmed that the anthropogenic activities were the leading source of DOM and N-nitrosamines in this city based on land-use.

Delivering drinking water with stable quality in metropolitan cities is a big challenge. This study investigated the year-long dynamics of dissolved organic matter (DOM) in the tap water and source water of a metropolitan city in southern China using fluorescence spectroscopy. The DOM detected in the tap water, and source water of Shenzhen city was season and location-dependent. A year-long cyclic trend of DOM was found with predominate protein-like fluorescence in the dry season compared to the humic-like enriched DOM in the wet season. A general DOM pattern was estimated by measuring the shift in dominant fluorescence regions on the excitation-emission matrix (EEM). The difference in fluorescent DOM (FDOM) composition (in terms of the ratio of protein-like to humic-like fluorescence) was above 200% between wet and dry seasons. The taps associated with reservoirs receiving water from the eastern tributary of Dongjiang River showed significant changes in protein-like contents than the taps with source water originating from the western part of the river. This study highlights the importance of optimizing drinking water treatment plants' operational conditions after considering seasonal changes and source water characteristics.

In this study, the effect of a high concentration of powdered activated carbon (PAC) on pollutant removal and microbial communities was systematically investigated. Micropollutant removal by the 'control' MBR (without PAC addition) was pollutant-specific and was mainly controlled by their molecular properties. The PAC-MBR achieved enhanced removal of micropollutant by 10% (ofloxacin) to 40% (caffeine). Analysis of the microbial communities in the sludge samples collected from both MBRs indicated an increase in the abundance of 24 (out of 31) genera following PAC addition. Notably, bacterial diversity enriched, particularly in the anoxic zone of the PAC-MBR, indicating a positive impact of recirculating mixed liquor containing PAC from the aerobic to the anoxic zone. In addition, PAC improved the abundance of Comamonas and Methanomethylovorans (up to 2.5%) that can degrade recalcitrant micropollutants. According to the quantitative PCR (qPCR) analysis, the copies of functional genes (nirS, nosZ and narG) increased in PAC-MBR. This study demonstrated that MBR could be operated at a high PAC concentration without compromising the pollutant removal and microbial community evolution during wastewater treatment.

Integration of an electrochemical process with membrane bioreactor (MBR) has attracted considerable attention in the last decade for simultaneous improvement in pollutant removal and hydraulic performance of MBR. Electrochemical MBR (eMBR) with sacrificial anodes has been observed to achieve enhanced phosphorus (up to 40%) and micropollutant removal (5-60%). This is because direct anodic oxidation, indirect oxidation by reactive oxygen species and electrocoagulation can supplement the biological process. The application of an electric field can substantially reduce membrane fouling by 10% to 95% in the eMBR as compared to the conventional MBR. Sacrificial electrodes (e.g., iron or aluminium) have been reported to be more suitable for fouling mitigation than non-sacrificial electrodes (e.g., titanium). However, during prolonged operation, metal ions released from sacrificial electrodes can adversely affect microbial activity and could accumulate in activated sludge. Depending on the current density and electrode material (sacrificial or non- sacrificial), anodic oxidation, electrocoagulation, electrophoresis and/or electroosmosis mechanisms are responsible for suppressing membrane fouling propensity. This paper critically reviews the current status of the electrochemical MBR technology and presents a concise summary of eMBR configurations and electrode materials. Comparative removal of bulk organics, nutrients and micropollutants in the eMBR and conventional MBR is discussed, and performance governing factors are elucidated. Impacts of operating conditions such as current density on mixed liquor properties (e.g., floc size and zeta potential) and microbial activity are elucidated. The extent of membrane fouling mitigation along with associated mechanisms as well as energy consumption is explained and critically analysed. Future research directions are suggested to fast track the scalability of eMBR, which include but are not limited to electrode lifetime, development of self-cleaning conductive membranes, optimisation of operating parameters, removal of emerging micropollutants, accumulation of toxic metals in activated sludge, and degradation by-products and ecotoxicity.

This study aims to extend and demonstrate the application of fluorescence spectroscopy for monitoring the water quality of three differently operated full-scale drinking water treatment plants located in the Shenzhen city (China). A ratio of fluorescent dissolved organic matter (FDOM), which describes relative changes in humic-like to protein-like fluorescence, was used to explain mechanisms behind the physicochemical processes. The fluorescence components obtained through individual and combined parallel factor analysis (PARAFAC) modeling revealed the presence of humic-like (C1) and protein-like (C2) structures in the DOM. The C1/C2 ratio provided a direct relationship between the seasonal variations and DOM composition. Wet season generated DOM enriched with humic-like fluorescence, while dry season caused a higher release of protein-like fluorescence. The fluorescence ratio presented unique patterns of DOM in treatment trains. The chemical pretreatment and disinfection unit processes showed a higher tendency to remove the humic-like fluorescence. However, the C1/C2 ratio increased during physical treatment processes such as coagulation-precipitation and sand filtration, indicating preferential removal of protein-like fluorescence. The DOM composition in influent directly (R2 = 0.77) influenced the relative intensities of fluorescence components in the treated water. Compared to the dry season, the wet season caused significant changes in DOM composition and produced treated water enriched with humic-like fluorescence. This fluorescence ratio offers an approach to explore the role of different treatment units and determine the factors affecting the composition of DOM in the surface water and drinking water treatment plants.

High retention membrane bioreactors (HR-MBR) combine a high retention membrane separation process such as membrane distillation, forward osmosis, or nanofiltration with a conventional activated sludge (CAS) process. Depending on the physicochemical properties of the trace organic contaminants (TrOCs) as well as the selected high retention membrane process, HR-MBR can achieve effective removal (80-99%) of a broad spectrum of TrOCs. An in-depth assessment of the available literature on HR-MBR performance suggests that compared to CAS and conventional MBRs (using micro- or ultra-filtration membrane), aqueous phase removal of TrOCs in HR-MBR is significantly better. Conceptually, longer retention time may significantly improve TrOC biodegradation, but there are insufficient data in the literature to evaluate the extent of TrOC biodegradation improvement by HR-MBR. The accumulation of hardly biodegradable TrOCs within the bioreactor of an HR-MBR system may complicate further treatment and beneficial reuse of sludge. In addition to TrOCs, accumulation of salts gradually increases the salinity in bioreactor and can adversely affect microbial activities. Strategies to mitigate these limitations are discussed. A qualitative framework is proposed to predict the contribution of the different key mechanisms of TrOC removal (i.e., membrane retention, biodegradation, and sorption) in HR-MBR.

With the aim to meet ever-increasing strict regulations for three major exhaust gas pollutants, three-way catalytic technology has been effectively applied in automobile industries for purifying automobile exhaust gases. Here we report the efficiency of composite oxide Co3O4/TiO2 with the addition of CeO2 as a promotor. Modification of Co3O4/TiO2 (15 wt%. Co/TiO2) based composite catalyst synthesized by incipient wetness impregnation (IWI) method was followed by doping of ceria (CeO2). The series of catalysts assigned as 15% IWI, 03-CE-IWI, 06-CE-IWI, and 09-CE-IWI having cerium content from 0 to 9 wt%, respectively were prepared. The same relative Co3O4/TiO2 ratio i.e., 15 wt% was sustained in the CeO2-doped catalysts for clarifying the impact of CeO2 and its doping quantity for CO and HC oxidation along with NOx reduction. The catalysts were characterized by Scanning Electron microscopy (SEM), X-ray Diffraction (XRD), and Brunauer–Emmett–Teller (BET). The catalysts three-way catalytic converter efficiency was assessed, mounted on a motorcycle engine with an engine capacity of 70 cm3 spark ignition. It was evaluated under steady-state operational conditions. The results revealed the strong impact of doping of CeO2 on Co3O4/TiO2 composite under real engine operating conditions and the maximum doping, i.e., 09-CE-IWI can considerably enhance the surface area (41.5 m2/g). The improved performance can be credited to a higher dispersion of Co3O4/TiO2 due to CeO2 doping, possessing a higher surface area as compared to ceria undoped catalysts, and there exists a catalytic synergistic effect of Co3O4 and CeO2. The 09-CE-IWI revealed the best catalytic activity for all three constituents i.e., CO and unburned HC at 6000 rpm and NOx specifically at 2000 rpm. Maximum three-way catalytic conversion efficiencies achieved in the case of CO, HC, and NOx are 92%, 83%, and 90%, respectively.

A novel membrane distillation – enzymatic membrane bioreactor (MD-EMBR) system was developed for efficient degradation of trace organic contaminants (TrOCs). Degradation of five TrOCs, namely carbamazepine, oxybenzone, diclofenac, atrazine and sulfamethoxazole was examined using two commercially available laccases (from Trametes versicolor and Aspergillus oryzae ). The MD system ensured complete retention (>99%) of both enzyme and TrOCs. Of particular interest was that the complete retention of the TrOCs resulted in high TrOC degradation by both laccases. Oxybenzone and diclofenac degradation in the MD-EMBR ranged between 80 and 99%. Compared to previously developed EMBRs, as much as 40% improvement in the removal of resistant non-phenolic TrOCs ( e.g., carbamazepine) was observed. Laccase from A. oryzae demonstrated better TrOC degradation and enzymatic stability. With the addition of redox mediators, namely 1-hydroxybenzotriazole (HBT) or violuric acid (VA), TrOC degradation was improved by 10–20%. This is the first demonstration of a laccase-based high retention membrane bioreactor for enhanced biodegradation of TrOCs.

Relaxation and backwashing have become an integral part of membrane bioreactor (MBR) operations for fouling control. This study was carried out on real municipal wastewater to evaluate the influence of different operational strategies on membrane fouling at equivalent water yield. Four relaxation modes (MBR10+0, MBR10+1, MBR10+1.5 and MBR10+2) were tested to analyze membrane fouling behavior. For the optimization of relaxation modes, fouling rate in terms of trans-membrane pressure, hydraulic resistances and characteristics of fouling fractions were analyzed. It has been observed that cake layer resistance was minimum in MBR10+1.5 but pore blockage resistance was increased in all relaxation modes. Moreover, high instantaneous flux contributed significantly to fouling rate at the initial stage of MBR operations. Relaxation modes were also efficient in removing irreversible fouling to some extent. Under all relaxation modes, COD removal efficiency ranged from 92 to 96.5%. Ammonium and TP removal were on the lower side due to the short solids and hydraulic retention time.

In biological wastewater treatment systems, extracellular polymeric substances (EPS) are continuously excreted as a response to environmental changes and substrate conditions. It could severely affect the treatment efficacy such as membrane fouling, dewaterability and the formation of carcinogenic disinfection by-products (DBPs). The heterogeneous dissolved organic matter (DOM) with varying size and chemical nature constitute a primary proportion of EPS. In the last few decades, fluorescence spectroscopy has received increasing attention for characterizing these organic substances due to the attractive features of this low-cost spectroscopic approach, including easy sample handling, rapid, non-destructive and highly sensitive nature. In this review, we summarize the application of fluorescence spectroscopy for characterizing EPS and provide the potential implications for online monitoring of water quality along with its limitations. We also link the dynamics of fluorescent dissolved organic matter (FDOM) in EPS with operational and environmental changes in wastewater treatment systems as well as their associations with metal binding, membrane fouling, adsorption, toxicity, and dewaterability. The multiple modes of exploration of fluorescence spectra, such as synchronous spectra with or without coupling with two-dimensional correlation spectroscopy (2D-COS), excitation-emission matrix (EEM) deconvoluted fluorescence regional integration (FRI), and parallel factor analysis (PARAFAC) are also discussed. The potential fluorescence indicators to depict the composition and bulk characteristics of EPS are also of interest. Further studies are highly recommended to expand the application of fluorescence spectroscopy paired with appropriate supplementary techniques to fully unravel the underlying mechanisms associated with EPS.

© 2019 Elsevier Ltd. This work aimed to evaluate the enrichment of lithium (Li) from a simulated salt lake brine by using an integrated nanofiltration (NF) and membrane distillation (MD) process. Two types of NF membranes, namely NF90 and NF270, were employed to compare their performances for Li and magnesium (Mg) rejection under various operating conditions. In the presence of a competing ion (i.e., Mg) at different concentration, Li rejection by NF90 and NF270 membrane increased, which could be attributed to ion-shielding effects. On the other hand, Li rejection by the NF membranes slightly reduced by increasing the applied pressure from 4 to 8 bar. Increasing the pH from 3 to 11 did not significantly affect Li rejection efficiency. Under optimum operating conditions, the Mg/Li molar ratio changed from 10 to 0.19 after NF90 treatment, and 10 to 2.1 after NF270 treatment. NF90 and NF270 membranes achieved 23 and 44% Li separation, respectively. The separated Li following NF treatments could be further enriched or concentrated significantly (80%) by using the direct contact-MD system. This study demonstrates that an integrated membrane process could be an efficient method for lithium recovery from salt lake brines.

Experiments were conducted to develop a statistical model which describes the relation between operating parameters and capacitive deionization performance for the removal of Ni(II) ion using multi-walled carbon nanotubes (MCNT) electrodes. The \(R^{2}\) value of 0.84 in regression analysis represents that the statistical model reproduced the data well. The factors for pH (\(a = 0.242\)), applied voltage (\(b = 0.619\)) and retention time (\(c = 0.504\)) in the statistical model revealed the significance of each parameter. The effect of initial Ni(II) concentration is best described by Langmuir isotherm. Kinetic study showed that pseudo-first-order equation fitted the data well. Modeling the performance with operating parameters for the removal of Ni(II) using MCNT electrodes is feasible, and results can be used for practical engineering applications.

The global demand of lithium is rising steadily, and many industrially advanced countries may find it hard to secure an uninterrupted supply of lithium for meeting their manufacturing demands. Thus, innovative processes for lithium recovery from a wide range of natural reserves should be explored for meeting the future demands. In this study, a novel integrated approach was investigated by combining nanofiltration (NF), membrane distillation (MD) and precipitation processes for lithium recovery from salt-lake brines. Initially, the brine was filtered with an NF membrane for the separation of lithium ions (Li+) from competing ions such as Na+, K+, Ca2+ and Mg2+. The extent of permeation of metal ions by the NF membrane was governed by their hydrated ionic radii. Rejection by NF membrane was 42% for Li, 48% for Na and 61% for K, while both the divalent cations were effectively rejected (above 90%). Importantly, in the NF-permeate, Mg2+/Li+ mass ratio reduced to less than 6 (suggested for lithium recovery). The result showed that MD can enrich lithium with a concentration of 2.5 for raw brine and 5 for NF-treated brine. Following the enrichment of NF-permeate by the MD membrane, a two-stage precipitation method was used for the recovery of lithium. X-ray diffraction confirmed the precipitation of lithium as well as the formation of lithium carbonate crystals.

N-nitrosamines have been identified as emerging contaminants with tremendous carcinogenic potential for human beings. This study examined the seasonal changes in the occurrence of N-nitrosamines and N-nitrosodimethylamine formation potential (NDMA-FP) in drinking water resources and potable water from 10 drinking water treatment plants in a southern city of China. The changes in N-nitrosamines are well correlated with dissolved organic matter (DOM), particularly fluorophores, which were measured and compared between traditional fluorescence indices and excitation-emission matrix coupled with parallel factor analysis (EEM-PARAFAC). Four of N-nitrosamine species including N-nitrosodimethylamine (NDMA), N-Nitrosodibutylamine (NDBA), N-Nitrosopyrrolidine (NPYR), and N-Nitrosodiphenylamine (NDPhA) are found to be abundant compounds with an average of 29.5% (26.7%), 20.0% (25.2%), 18.9% (16.0%), and 9.0% (9.9%) in the source (and treated) water, respectively. The sum of N-nitrosamines concentration is recorded to be low in the wet season (July-September), whereas the dry season (October-December) provided opposite impacts. EEM-PARAFAC modeling indicated the predominance of humic-like component (C1) in the wet season while in the dry season the water was dominant in protein-like component (C2). All the N-nitrosamines excluding NDPhA and N-Nitrosomorpholine (NMOR) showed a strong association with protein-like component (C2). In contrast, humic-like C1, which was directly influenced by rainfall, was found to be a suitable proxy for NMOR and NDPhA. The results of this study are valuable to understand the correlation between different N-nitrosamines and DOM through adopting fluorescence signatures.

This study systematically compares the performance of ultrafiltration (UF) and nanofiltration (NF) based enzymatic membrane bioreactors (EMBRs) for the degradation of five micropollutants, namely atrazine, carbamazepine, sulfamethoxazole, diclofenac and oxybenzone to elucidate the impact of effective membrane retention of micropollutants on their degradation. Based on the permeate quality, NF-EMBR achieved 92–99.9% micropollutant removal (i.e., biodegradation + membrane retention), while the removal of these micropollutants by UF-EMBR varied from 20 to 85%. Mass balance analysis revealed that micropollutant degradation was improved by 15–30% in NF-EMBR as compared to UF-EMBR, which could be attributed to the prolonged contact time between laccase and micropollutants following their effective retention by the NF membrane. A small decline in permeate flux was observed during EMBR operation. However, the flux could be recovered by flushing the membrane with permeate.

Occurrence of pharmaceutically active compounds (PhACs) in marine ecosystems has been confirmed in recent studies. These PhACs include human pharmaceuticals, veterinary medicines and those used in aquaculture . Levels of PhACs in the marine environment are suspected to rise in future due to the increase in anthropogenic activities. This chapter critically discusses the occurrence, sources and fate of PhACs in marine environment. A particular focus has been given to the adverse impacts of PhACs on marine biota and the potential exposure to human. Data related to the distribution of PhACs in seawater , sea sediments and marine biota is presented to elucidate their bioconcentration and bioaccumulation potential. Impacts of PhACs at cellular, molecular and species level are summarised here to understand their mode of action. Lastly, potential biomarkers for effective biomonitoring of marine environment are highlighted to anticipate the risks related to marine ecosystem and human health.

© 2017 by the authors. A high retention enzymatic bioreactor was developed by coupling membrane distillation with an enzymatic bioreactor (MD-EMBR) to investigate the degradation of 13 phenolic and 17 non-phenolic trace organic contaminants (TrOCs). TrOCs were effectively retained (90–99%) by the MD membrane. Furthermore, significant laccase-catalyzed degradation (80–99%) was achieved for 10 phenolic and 3 non-phenolic TrOCs that contain strong electron donating functional groups. For the remaining TrOCs, enzymatic degradation ranged from 40 to 65%. This is still higher than those reported for enzymatic bioreactors equipped with ultrafiltration membranes, which retained laccase but not the TrOCs. Addition of three redox-mediators, namely syringaldehyde (SA), violuric acid (VA) and 1-hydroxybenzotriazole (HBT), in the MD-EMBR significantly broadened the spectrum of efficiently degraded TrOCs. Among the tested redox-mediators, VA (0.5 mM) was the most efficient and versatile mediator for enhanced TrOC degradation. The final effluent (i.e., membrane permeate) toxicity was below the detection limit, although there was a mediator-specific increase in toxicity of the bioreactor media.

© 2017 Elsevier Ltd Laccase-catalyzed degradation of a broad spectrum of trace organic contaminants (TrOCs) by a membrane distillation (MD)-enzymatic membrane bioreactor (EMBR) was investigated. The MD component effectively retained TrOCs (94–99%) in the EMBR, facilitating their continuous biocatalytic degradation. Notably, the extent of TrOC degradation was strongly influenced by their molecular properties. A significant degradation (above 90%) of TrOCs containing strong electron donating functional groups (e.g., hydroxyl and amine groups) was achieved, while a moderate removal was observed for TrOCs containing electron withdrawing functional groups (e.g., amide and halogen groups). Separate addition of two redox-mediators, namely syringaldehyde and violuric acid, further improved TrOC degradation by laccase. However, a mixture of both showed a reduced performance for a few pharmaceuticals such as primidone, carbamazepine and ibuprofen. Mediator addition increased the toxicity of the media in the enzymatic bioreactor, but the membrane permeate (i.e., final effluent) was non-toxic, suggesting an added advantage of coupling MD with EMBR.

White-rot fungi (WRF) mediated treatment can offer an environmentally friendly platform for the removal of pharmaceuticals and personal care products (PPCPs) from wastewater. These PPCPs may have adverse impacts on aquatic organisms and even human and thus their removal during wastewater treatment is of significant interest to the water industry. Whole-cell WRF or their extracellular lignin modifying enzymes (LMEs) have been reported to efficiently degrade PPCPs that are persistent to conventional activated sludge process. WRF mediated treatment of PPCPs depends on a number of factors including physicochemical properties of PPCPs (e.g., hydrophobicity and chemical structure) and wastewater matrix (e.g., pH, temperature, and dissolved constituents), type of WRF species and their specific extracellular enzymes. This review critically analyzes the performance of whole-cell WRF and their LMEs for the removal of PPCPs; particularly, it offers insights into PPCP removal mechanisms (e.g., biosorption vs. biodegradation) and degradation pathways as well as the formation of intermediate byproducts.

© 2017 Elsevier Ltd White-rot fungi (WRF) and their ligninolytic enzymes have been investigated for the removal of a broad spectrum of trace organic contaminants (TrOCs) mostly from synthetic wastewater in lab-scale experiments. Only a few studies have reported the efficiency of such systems for the removal of TrOCs from real wastewater. Wastewater derived organic and inorganic compounds can inhibit: (i) WRF growth and their enzyme production capacity; (ii) enzymatic activity of ligninolytic enzymes; and (iii) catalytic efficiency of both WRF and enzymes. It is observed that essential metals such as Cu, Mn and Co at trace concertation (up to 1 mM) can improve the growth of WRF species, whereas non-essential metal such as Pb, Cd and Hg at 1 mM concentration can inhibit WRF growth and their enzyme production. In the case of purified enzymes, most of the tested metals at 1–5 mM concentration do not significantly inhibit the activity of laccases. Organic interfering compounds such as oxalic acid and ethylenediaminetetraacetic acid (EDTA) at 1 mM concentration are potent inhibitors of WRF and their extracellular enzymes. However, inhibitory effects induced by interfering compounds are strongly influenced by the type of WRF species as well as experimental conditions (e.g., incubation time and TrOC type). In this review, mechanisms and factors governing the interactions of interfering compounds with WRF and their ligninolytic enzymes are reviewed and elucidated. In addition, the performance of WRF and their ligninolytic enzymes for the removal of TrOCs from synthetic and real wastewater is critically summarized.

Pakistan is increasingly confronted with shortage of fresh water resources, as annual per capita water availability has reduced to less than 1,000 m3. Wastewater reclamation and reuse practices must be adopted to deal with the situation. For this purpose, small and medium scale industries can play a vital role. With this mind set, wastewater from Al-Kausar Flour Mills Islamabad (AFM), Pakistan was investigated using physico-chemical treatment options. Total water consumption of AFM is 74.1 m3/d, and groundwater is being pumped for 8 h/d. Four experimental trains were tested using various combinations of pre-sedimentation, horizontal roughing filter, coagulation/flocculation/settling setup, and multimedia filtration. Ferric chloride and alum were used as coagulants. Results revealed that flour mill wastewater had high concentration of total suspended solids. Ferric chloride provided appreciable suspended solids removal in terms of turbidity. While, every option tested, removed over 98% of turbidity...