Performance of constructed wetland for selenium, nutrient and heavy metals removal from mine effluents.

Passive biological treatment using constructed wetlands has been employed as a cost-effective and environmentally friendly alternative for mine effluents treatment in Canada. The current work aimed to assess the performance of a laboratory-scale constructed wetland for the removal of selenium, nutrients and heavy metals. This work achieved a maximum selenium removal rate of 54.13% corresponding to the highest hydraulic residence time (almost 47 days). Typha Latifolia was efficient for selenium assimilation and removal from mine effluent. 4.4% of Se mass was accumulated in the under and aboveground biomass while 32.2% was volatilized. Levels <1.69 mg of selenate, <1.69 mg of selenite, <3.39 mg of selenomethionine and <3.39 mg of unknown selenium species were distributed in the underground biomass while levels <0.75 mg of selenate, <0.75 mg of selenite, <1.51 mg of selenomethionine and <1.51 mg of unknown selenium species were found in T. Latifolia leaves. Ammonia removal was mainly based on a nitrification process confirmed by the decrease of ammonia (>96%) and nitrite in association with the increase of nitrate concentrations in the outlet compared to the inlet. The concentrations of other nitrogen compounds mainly thiocyanate and cyanate have significantly decreased from initial average values of 163 and 22.7 mg.L-1 in the influent to 1.5 and 0.3 mg.L-1 final concentrations, respectively. Orthophosphate concentrations were also efficiently decreased from an influent average value of 21.5 ± 3.3 mg.L-1 to an effluent concentration of 9.1 ± 4.4 mg.L-1. Understanding the selenium and nutrient removal mechanisms will allow treatment performance enhancement and the development of large-scale constructed wetlands for sophisticated mine effluent treatment.

Selenium speciation and bioavailability from mine discharge to the environment: a field study in Northern Quebec, Canada.

The speciation, behaviour, and bioavailability of released selenium (Se) from mine effluent discharge to sediments and plants were assessed. Discharged mine effluent containing 65±0.9 µg/L of total Se subsequently contaminated the exposed sediment with an average total Se concentration of 321 mg/kg as well as exposed Typha latifolia plants where 534 and 92 mg/kg were found in roots and leaves, respectively. The strategy of T. latifolia in Se phytoremediation consisted of a phytostabilization and accumulation of Se predominantly in roots. Se plant root uptake was promoted by synergistic effects of Cu, Pb, Zn, and Cd while Co, Fe, Mn, Ni, Na, K, and Mg had antagonistic effects. Se plant uptake was also governed by sediment characteristics mainly pH, total Se, and iron concentration. Se speciation results demonstrated that the most accumulated Se species by T. latifolia roots were selenite and selenomethionine with average concentrations of 2.68 and 2.04 mg/kg respectively while other Se species were the most translocated (average translocation factor of 1.89). Se speciation in roots was positively correlated with sediment pH, organic matter, electrical conductivity, and iron concentration. This study confirms deploying corrective measures for mine effluent treatment before discharge in a sediment-plant environment to protect living organisms from toxic effects. T. latifolia is recommended as a Se-hyperaccumulator to be used for mine soil phytoremediation in cold regions in Canada.

A Rapid Assay to Assess Nitrification Inhibition Using a Panel of Bacterial Strains and Partial Least Squares Modeling.

As a proof of concept, a rapid assay consisting of a cell-based biosensor (CBB) panel of pure bacterial strains, a fluorescent dye, and partial least squares (PLS) modeling was developed to assess the nitrification inhibition potential of industrial wastewater (WW) samples. The current standard method used to assess the nitrification inhibition potential is the specific nitrification rate (SNR) batch test, which requires approximately 4 h to complete under the watch of an experienced operator. In this study, we exposed the CBB panel of seven bacterial strains (nitrifying and non-nitrifying) to 28 different industrial WW samples and then probed both the membrane integrity and cellular activity using a commercially available "live/dead" fluorescent dye. The CBB panel response acts as a surrogate measurement for the performance of nitrification. Of the seven strains, four (Nitrospira, Escherichia coli, Bacillus subtilis, Bacillus cereus) were identified via the modeling technique to be the most significant contributors for predicting the nitrification inhibition potential. The key outcome from this work is that the CBB panel fluorescence data (collected in approximately 10 min) can accurately predict the outcome of an SNR batch test (that takes 4 h) when performed with the same WW samples and has a strong potential to approximate the chemical composition of these WW samples using PLS modeling. Overall, this is a powerful technique that can be used for point-of-use detection of nitrification inhibition.

Virulence genes expression in viable but non-culturable state of Listeria monocytogenes in fish meat.

This study aimed to evaluate the fate of Listeria monocytogenes in water microcosm and rainbow trout fillet under salinity stress of 0% and 30% NaCl at refrigerator temperature (4 ± 2 ℃). Bacterial culturability was studied by standard culture and colony count method. Reverse transcription-PCR (RT-PCR) of 16 S rRNA gene was used to detect viability of non-culturable bacteria. Also, the qualitative expression of pathogenic genes (hly and inlA) was studied using RT-PCR. The results showed that bacteria in water microcosm lost their culturability at 13 days under 0% salinity (starvation or distilled water) and at 27 days under 30% salinity; however, bacteria in rainbow trout fillet remained culturable under 0% and 30% NaCl. RT-PCR of 16 S rRNA gene was positive for all treatments during the period of this study, indicating the entering of L. monocytogenes into the viable but non-culturable state in water microcosm under 0% and 30% NaCl. Also, viable but non-culturable L. monocytogenes retained the expression of hly and inlA genes. So, it could be concluded that L. monocytogenes in viable but non-culturable state can cause serious health problems and further investigation is necessary to elucidate the effects of other processing and storage conditions (light, dark, smoking, etc.) on behavior of L. monocytogenes in smoked and salted fish.

Monitoring and analysis of selenium as an emerging contaminant in mining industry: A critical review.

Selenium is an indispensable trace element for humans, however, its release at high concentrations becomes a major concern for terrestrial and aquatic ecosystems due to its bioaccumulation potential. Mining and metal-mineral processing are among the main sources of selenium released into the environment. Excessive levels of selenium may induce toxicity in human as selenosis, in grazing animals as alkali disease and in aquatic organisms as larval and developmental deformities and mortality. Due to the introduction of new policies for Se monitoring in the mining industry mainly setting the guidelines for selenium level in freshwaters as recommended by the Canadian Council of Ministers of Environment and Environment and climate change Canada, an improved understanding of Se occurrence, mobility, bioavailability and treatment technologies for efficient removal is timely and required. In this context, this review updated the understanding of mining-related selenium occurrence in surface water, soil and plant, with a focus on its mobility and bioavailability. Selenium uptake, translocation, accumulation, and metabolism in plants are further presented. Selenium monitoring and treatment is the key to adopt the corrective measures to mitigate highly contaminated effluent and to minimize the associated adverse health effects. Future research directions and recommendations for selenium analysis and treatment processes are also discussed.

Standardization of Plasma Rich in Growth Factors (PRGF) and its effects on androgenic hair loss.

Androgenic alopecia (AGA), as the most common cause of hair loss, is a chronic process that affects 80% of men and 50% of women throughout life. Existing and approved treatments for this condition are limited, and unfortunately, the length of treatment is long, while its efficacy is not much suitable. Plasma rich in growth factors (PRGF) autologous therapy is based on the delivery of a pool of bioactive molecules impressive for the treatment of AGA.Thirteen patients were included in this study. Our patients were evaluated in two groups: the first group was injected once and the second group was injected thrice, then evaluated for the number and diameter of the hair.Both groups of patients showed hopeful results so that in the first group hairs number and thickness increased by 9-54% and 11-76% respectively (p < .01). For patients who underwent PRGF injection thrice, the increases in hairs number and thickness were remarkably higher with an average of 211 and 221 respectively (p < .001). No adverse effect was reported in any patient.Our results revealed that PRGF platelet concentration using a higher volume of blood compared to previous protocols has higher effectiveness in treating AGA. However, more randomized clinical studies with longer follow up courses as well as larger sample sizes are needed to standardize an optimum protocol for PRGF based treatments.

Optimization of microorganism preservation conditions for the development of an acute toxicity bioassay for biocides.

Biocides, also referred to as 'microbicides' or 'inhibitors', are widely used in industrial processes (e.g. utility water in cooling towers) to control and/or eliminate the growth of microorganisms. Because of their inherent toxicity, their presence in various sources (e.g. river sediments, potable water) can negatively affect ecosystems. Currently available biocide detection techniques are not suitable for 'point-of-use' applications since they are tedious, complicated, and often require experienced personnel to operate. To address this concern, we sought to develop a simple-to-use toxicity bioassay based on a model microorganism (E. coli) after short (<30 min) exposure to known biocides that can be stored at room temperature (preferably) or in the fridge. Based on recent work and our expertise in polymer-based preservation of biomolecules, we leveraged this knowledge to improve E. coli preservation for biocide detection purposes. A design-of-experiments strategy was used to evaluate 16 different preservation conditions from 5 process parameters (i.e. 25-1 fractional factorial). It was found that pullulan, a sugar-based polymer, improved E. coli culturability by an order of magnitude after three months of storage. Also, it was found that storing E. coli in the fridge in Milli-Q water was favorable for maintaining a high level of culturability. Finally, the toxicity of three common biocides (Cetyltrimethylammonium bromide (CTAB), ProClin™ 300, and Grotan® BK) was evaluated using a fluorescence-based assay across all 16 preservation conditions. The response of the preserved E. coli was biocide specific and at certain conditions did not vary during the entire three-month storage period.

Acute Impact of Chlortetracycline on Nitrifying and Denitrifying Processes.

In the current study, sequential nitrification and anoxic experiments in synthetic municipal wastewater were exposed to 0.5 to 100 mg/L of chlortetracycline for 24 h to evaluate acute impact on the nitrification, and denitrification processes of biological treatment. Both processes were significantly (p < 0.05) inhibited at >50 mg/L of chlortetracycline, and the results revealed that nitrification was adversely affected by chlortetracycline compared with the anoxic process. In nitrification, chemical oxygen removal (COD) and ammonia oxidation kinetics were 50% inhibited at 10 mg chlortetracycline/L, and nitrite oxidation kinetics at 0.5 mg chlortetracycline/L. Likewise, in the anoxic process, 14 and 10 mg/L of chlortetracycline inhibited 50% of COD removal and nitrate reduction kinetics, respectively. In nitrification and denitrification, 90% of chlortetracycline was removed by adsorbing onto sludge suspended solids. In addition, a higher chlortetracycline concentration in anoxic effluent, compared with aerobic effluents, indicated a dissimilarity in the composition of sludge solids, pH, and biomass production for both processes.

Removal of Pollutants in Different Landfill Leachate Treatment Processes on the Basis of Organic Matter Fractionation.

A combination of processes was required for the proper treatment of old landfill leachate, as it contained a high concentration of pollutants. Humic substances comprised half of the total organic carbon in the raw leachate. Mobility of di(2-ethylhexyl) phthalate (DEHP) and metals could depend on the fate of these substances. Characterization of carbon in raw leachate and effluent of the membrane bioreactor, biofiltration, electro-oxidation, electro-coagulation, and nanofiltration showed complete removal of suspended solids and colloids. Physical processes could not remove the hydrophilic fraction due to its lower molecular weight. However, high removal of the hydrophilic fraction with a molecular weight <500 Da was expected in the biological process. In comparison with fulvic acid, larger sized humic acid resulted in complete removal by physicochemical processes. Because of DEHP partitioning on dissolved organic matter, especially on humic substances, its removal could be correlated with total organic carbon removal. Metals such as iron, aluminum, magnesium, and lead showed removal efficiency >80% in biological processes. Electro-deposition on the surface of an electrode and precipitation by hydroxide resulted in removal efficiencies >90 and >50% in electro-coagulation and electro-oxidation, respectively. Rejection of metals by nanofiltration was >80% and depended on the size and charge of cation. All in all, a combination of membrane bioreactor and nanofiltration seems to be the optimal process configuration for efficient treatment of old landfill leachate.

Performance of a membrane bioreactor in extreme concentrations of bisphenol A.

In this study, a submerged membrane bioreactor was used to study the effect of low and high bisphenol A (BPA) concentration on the sludge biological activity. The pilot was operated over 540 days with hydraulic retention time and solid retention time of 5.5 hours and 140 days, respectively. As a hydrophobic compound, BPA was highly adsorbed by activated sludge. In lower concentrations, the biodegradation rate remained low, since the BPA concentration in the sludge was lower than 0.5 mg/g TS; yet, at an influent concentration up to 15 mg/L, the biodegradation rate was increasing, resulting in 99% BPA removal efficiency. The result for chemical oxygen demand removal showed that BPA concentration has no effect on the heterotrophic bacteria that were responsible for the organic carbon degradation. In higher concentrations, up to 16 mg of BPA was used for each gram of sludge as a source of carbon. However, the activity of autotrophic bacteria, including nitrifiers, was completely halted in the presence of 20 mg/L of BPA or more. Although nitrification was stopped after day 400, ammonia removal remained higher than 70% due to air stripping. Assimilation by bacteria was the only removal pathway for phosphorus, which resulted in an average 35% of P-PO4 removal efficiency.

Removal of macro-pollutants in oily wastewater obtained from soil remediation plant using electro-oxidation process.

Electro-oxidation process by niobium boron-doped diamond (Nb/BDD) electrode was used to treat non-biodegradable oily wastewater provided from soil leachate contaminated by hydrocarbons. Firstly, the diffusion current limit and mass transfer coefficient was experimentally measured (7.1 mA cm-2 and 14.7 µm s-1, respectively), in order to understand minimum applied current density. Later on, the oxidation kinetic model of each pollutant was investigated in different current densities ranged between 3.8 and 61.5 mA cm-2. It was observed that direct oxidation was the main removal mechanism of organic and inorganic carbon, while the indirect oxidation in higher current density was responsible for nitrogen oxidation. Hydrocarbon in the form of colloidal particles could be removed by electro-flotation. On the other hand, electro-decomposition on the surface of cathode and precipitation by hydroxyl ions were the utmost removal pathway of metals. According to the initial experiments, operating condition was further optimized by central composite design model in different current density, treatment time, and electrolyte addition, based on the best responses on the specific energy consumption (SEC), chemical oxygen demand (COD), and total organic carbon (TOC) removal efficiency. Unde r optimum operating condition (current density = 23.1 mA cm-2, time = 120 min, Ti/Pt as a cathode, and Nb/BDD as the anode), electro-oxidation showed the following removal efficiencies: COD (84.6%), TOC (68.2%), oil and grease (99%), color (87.9%), total alkalinity (92%), Ntot (18%), NH4+ (31%), Ca (66.4%), Fe (71.1%), Mg (41.4%), Mn (78.1%), Ptot (75%), S (67.1%), and Si (19.1%). Graphical abstract Environmental significance statement Soil treatment facilities are rapidly grown throughout the world, especially in North America due to its intense industrialization. High water content soil in humid area like Canada produces significant amount of leachate which is difficult to remove by physical and biological processes. Current treatment facility was modified by applying the electro-chemical oxidation process. The kinetic models of each macro-pollutant included carbon, nitrogen, phosphorous, and metals were developed to investigate their oxidation mechanism (graphical abstract). The efficiency of treatment was monitored in order to optimize the decisive operating parameters of electro-oxidation process. The result of this article could pave the way of future investigation on efficient treatment of variety of oily wastewater.

Insight into the adsorption mechanisms of trace organic carbon on biological treatment process.

The presence of recalcitrant dissolved organic matter (DOM) could have a significant effect on the adsorption mechanism and capacity of the sludge for many trace organic carbons (TrOCs). In this study, adsorption of three TrOCs on the sludge and HA was investigated. The results revealed that neutral hydrophilic compounds had an insignificant interaction with both sludge and HA. Positively charged compounds, such as fluoranthene, had more affinity toward HA than sludge with solid/liquid partitioning of 57 and 3.2 L/g, respectively. The adsorption intensity (Kf) of di-2-ethyl hexyl phthalate was 0.5 and 1.13 for the HA and the sludge, respectively. By introducing the sludge to the solution of HA and TrOCs that already reached equilibrium, the sludge adsorption capacity in the presence of HA was investigated. The finding showed that at the lower concentration, adsorption of HA on the sludge was considered as the main removal pathway for the adsorbed emerging contaminants, as 70 mg of HA was adsorbed by a gram of sludge. For the higher concentration, desorption of TrOCs from DOM into the sludge comprised 15-30% of total removal efficiency. ABBREVIATIONS: CBZ: carbamazepine; DEHP: di-2-ethyl hexyl phthalate; DOM: dissolved organic matter; FLAN: fluoranthene; foc: fraction of organic carbon; HA: humic acid; Log Kow: octanol-water partition coefficient; PAH: polycyclic aromatic hydrocarbon TS: total solid; TrOCs: trace organic carbons VS: volatile solid.

Landfill leachate treatment by sequential membrane bioreactor and electro-oxidation processes.

Combination of high performance membrane bioreactor (MBR) equipped with ultrafiltration and electro-oxidation process (EOP) by boron-doped diamond electrode (BDD) was used to effectively treat highly contaminated old landfill leachate. MBR and EOP were optimized for raw and pretreated landfill leachate. Seasonal changes dramatically affected the both processes' performance, as the landfill leachate was ¾ more concentrated in winter. For MBR, organic load rate of 1.2 gCOD/L/day and sludge retention time of 80 days was considered as the optimum operating condition in which COD, TOC, NH4+ and phosphorous removal efficiencies reached the average of 63, 35, 98 and 52%, respectively. The best performance of EOP was in current intensity of 3 A with treatment of time of 120 min. Effluent of electro-oxidation was more toxic due to the presence of radicals and organochlorinated compounds. These compounds were removed by stripping or assimilation of sludge if EOP was used as a pretreatment method. Furthermore, the energy consumption of EOP was decreased from 22 to 16 KWh/m3 for biologically treated and raw landfill leachate, respectively.

Performance of electrochemical oxidation process for removal of di (2-ethylhexyl) phthalate.

Di (2-ethylhexyl) phthalate (DEHP) is the most detected and concentrated plasticizer in environment and wastewaters, worldwide. In this study, different operating parameters such as current intensity, treatment time, type of anodes, and supporting electrolytes were tested to optimized the electro-oxidation process (EOP) for the removal of DEHP in the presence of methanol as a dissolved organic matter. Among the anodes, the Nb/BDD showed the best degradation rate of DEHP, at low current intensity of 0.2 A after 90 min of treatment time with a percentage of degradation recorded of 81 %, compared to 70 % obtained with the Ti/IrO2-RuO2. Furthermore, due to the combination of direct and indirect oxidation, the removal of DEHP in the presence of 1 g/L Na2SO4 was higher than NaBr, even though the oxidant production of NaBr was 11.7 mmol/L against 3.5 mmol/L recorded in the presence of sulfate at 0.5 A and after 60 min of electrolysis time. Under optimal condition (current intensity = 0.5 A, time = 120 min, using Nb/BDD anode and Na2SO4 as supporting electrolyte), the removal of 87.2 % of DEHP was achieved. The total cost of 0.106 US$/m(3) of treated water was achieved based on economical optimization of reactor with current intensity of 0.2 A and 1 g/L Na2SO4.

Investigation on removal pathways of Di 2-ethyl hexyl phthalate from synthetic municipal wastewater using a submerged membrane bioreactor.

Highly hydrophobic Di 2-ethyl hexyl phthalate (DEHP) is one of the most prevalent plasticizers in wastewaters. Since its half-life in biological treatment is around 25days, it can be used as an efficiency indicator of wastewater treatment plant for the removal of hydrophobic emerging contaminants. In this study, the performance of submerged membrane bioreactor was monitored to understand the effect of DEHP on the growth of aerobic microorganisms. The data showed that the chemical oxygen demand (COD) and ammonia concentration were detected below 10 and 1.0mg/L, respectively for operating conditions of hydraulic retention time (HRT)=4 and 6hr, sludge retention time (SRT)=140day and sludge concentration between 11.5 and 15.8g volatile solid (VS)/L. The removal efficiency of DEHP under these conditions was higher and ranged between 91% and 98%. Results also showed that the removal efficiency of DEHP in biological treatment depended on the concentration of sludge, as adsorption is the main mechanism of its removal. For the submerged membrane bioreactor, the pore size is the pivotal factor for DEHP removal, since it determines the amount of soluble microbial products coming out of the process. Highly assimilated microorganisms increase the biodegradation rate, as 74% of inlet DEHP was biodegraded; however, the concentration of DEHP inside sludge was beyond the discharge limit. Understanding the fate of DEHP in membrane bioreactor, which is one of the most promising and futuristic treatment process could provide replacement for conventional processes to satisfy the future stricter regulations on emerging contaminants.