Mercury pollution is an issue of global concern. In Colombia, the use of contaminated water for food crop irrigation and artisanal mining contributes to mercury pollution in soil, affecting food production and restoration of disturbed areas. Mycorrhizal fungi are symbionts that provide benefits to plants including resistance to heavy metals, but fungal effects on germination remain to be fully described. This study tested the effect of mercury and mycorrhizal fungi on Lactuca sativa seed germination. A 2x5 completely randomized factorial experiment was developed to assess the effect of five HgCl2 polluted treatments, two mycorrhizal treatments (i.e., with inoculum, without inoculum), and the interaction of both factors on seed germination, seedling root colonization, pH, and final water content. In samples with no mercury pollution, mycorrhizal fungi had an inhibitory effect on seed germination. Likewise, the effect of mercury on seed germination is significantly inhibitory. However, pots inoculated with arbuscular mycorrhizal fungi showed constant germination probabilities, independently of mercury concentration. According to the best model determined for the data, a key step in the mitigation of mercury toxicity in seed germination is to prevent substrate pH changes. The environmental conditions of the experiment contributed to densely activate populated biomass of inoculum, which promoted root invasion from various points. Overall, the presence of mycorrhizal fungi in seedbeds could lead to a reduced number of plant individuals. However, the use of fungal inoculum in polluted environments, highly contributes to plant establishment, which is relevant in further vegetable cultivations growing in soil polluted areas.

Lignin rich solid residues after saccharification during the production of ethanol from lignocellulosic substrates are major concern during past times. These solid residues left after the saccharification of Coir pith and Bit fiber waste are pyrolysed at 350 oC to yield biochar, which has been characterized and its potential for removal of Malachite Green, a dye present in the effluents from coir product manufacturing units are studied. FTIR and XRD spectra revealed the diverse functional groups present on the surface of biochar. SEM images showed the porous structure of the biochar. A maximum dye removal efficiency of 99.5% was achieved using Coir Pith Biochar (1 %) within 24 hours of treatment at a dye concentration of 100 mg/l. The removal efficiency was 99.4 % using Bit Fiber Biochar (0.8 %) in the same treatment period. The efficiency of removal was enhanced on adjusting the pH to 4 at which the dye removal of 99.6 % and 99.7 % was achieved using Bit fiber biochar and Coir pith biochar respectively. The residence time was significantly reduced to 2 and 4 hours respectively for bit fiber and coir pith biochar at pH 4 and hence the produced biochars are cost effective adsorbents for removal of dyeing effluents in wastewater. The adsorption fits into pseudo-second order kinetics and is well described by langmuir isotherm model. This would also facilitate the sustainable use of spent solid substrates left after lignocellulosic ethanol production in a more economical way.

Solar disinfection is becoming increasingly popular around the world for eliminating pathogens present in wastewater. The goals of this study were to identify the significant variables and to maximize the log reduction values (LRV) of total coliforms present in treated urban wastewater using solar disinfection. To achieve the goals, a 23 full factorial design of experiments and response surface methodology were used. Solar disinfection was carried out in an open-air batch reactor and in a solar batch reactor. The three variables considered were solar irradiation, volume of sample and exposure time at two markedly different levels: solar irradiation (1100 Wh/m2 and 1700 Wh/m2), volume of sample (0.2 L and 2L), and exposure time (0.5 h and 3 h). When compared to other variables, exposure time was the most significant factor in the analysis of variance (ANOVA) study for both the reactor conditions. The regression equation developed for a solar reactor does not adequately explain the variability of the experimental data when compared to the regression equation developed for an open-air reactor. According to the response optimizer, the optimum values of the factors for solar disinfection using a solar reactor to achieve an LRV of 2 for 0.25 L of sample volume are 1700 Wh/m2 solar irradiation and 2.97 hours of exposure time. With an open-air reactor, 0.2 L of sample must be exposed to 1700 Wh/m2 of solar irradiation for 3 hours to achieve LRV of 2.

The optimization of nickel ion (Ni2+) removal in aqueous solutions with various factors (initial Ni concentration, solution pH, adsorbent dosage, contact time), as affected by raw cow bone (RBO) and its biochar (bone char: BC; produced by pyrolysis processes at 500 °C and a residence time of 4 hours) as adsorbents was investigated by a three-level Box–Behnken model (BBM) under response surface methodology (RSM). A total of 29 experimental runs were set for each adsorbent, and the experimental data were fitted to the empirical model. To understand the Ni2+ adsorption processes better, the properties of RBO and BC were characterized using Fe-SEM, FT-IR, BET, XRD, and CHNS elemental analysis techniques. The BC characteristics showed that pyrolysis increased the specific surface area (by 100 times) and phosphate functional groups, but decreased the carbonate functional groups, and yielded a more irregular and rougher morphological surface compared to RBO. Based on BC's superior ion exchange mechanisms and physical electrostatic adsorption compared to RBO, the removal efficiency of Ni2+ by BC was higher in aqueous solutions. The numerical optimization of BBM revealed that the optimum removal by BC (82.56%) was obtained at an initial Ni2+ concentration of 30.79 mg L−1, pH of 6.99, adsorbent dose of 4.87 g L−1, and contact time of 57.82 min, with the desirability of "1". BC can be effectively used for Ni removal from Ni-contaminated aqueous solutions; still, the application of modification methods (e.g., physical and chemical activation) may be necessary to help remove more Ni2+ by BC.

Melanoidin is the hazardous dark brown byproduct generated during palm oil extraction in the crude palm oil industry. In this study, the laccase-producing consortium W3 (Bacillus licheniformis and Bacillus subtilis) was used to degrade melanoidin and decolorize palm oil mill effluent (POME). The microbial fuel cell (MFC) has been applied for enhancing decolorization and generation of electrical energy as a byproduct. The results displayed the maximal melanoidin removal of 95.20±0.10% was gained when the consortium W3 was added into the synthetic wastewater. While the maximal decolorization of 75.10±0.12% and 73.91±0.23% were gained from the sterile POME and raw POME respectively without chemical addition. Moreover, the power output of 2.13±0.05 W/m3 or 0.27±0.01 W/m2 was achieved from the POME-fed MFC with W3. This study gained new knowledge of using the laccase-producing bacterial consortium integrated with MFC for melanoidin removal from the POME and generation of electrical power as an alternative energy source.

Activated carbon is known an as appropriate adsorbent due to its high adsorption capacity for most pollutants, especially heavy metals. In the present study, activated carbon was synthesized from orange wood by employing the chemical activation method. Additionally, cysteine amino acid was used to modify the activated carbon surface, leading to an enhancement in adsorption ability because of having a nitrogen group. Based on the results, the adsorption capacity of the modified activated carbon was obtained at 120 mg g-1 adsorbent. The parameters affecting adsorption such as the amount of used adsorbent, as well as solution pH, primary concentration, and contact time were optimized, followed by performing the adsorption process under optimal conditions. The optimal adsorption conditions included the pH of 6, contact time of 60 min, adsorbent amount of 50 mg, and primary cadmium concentration of 80 ppm. Further, kinetic and thermodynamic parameters were assessed and optimized. The results of which represented the best fit between adsorption with Langmuir isotherm and the pseudo-second-order kinetic model. The results represented that the quasi-second-order model with a higher regression coefficient (R2 = 0.97) described the experimental data better than the quasi-first-order one (R2 = 0.83). The adherence of adsorption kinetics to the pseudo-second-order model suggested a chemical interaction as the rate-determining step. Regarding adsorption thermodynamics, the effect of temperature was examined on adsorption by using Van't Hoff's equations, which reflect the endothermicity of the process.

There is great competition to improve the performance of membranes for water treatment within the scope of the research, especially the problem of biofouling on the membrane as it is related to the performance and life of the membrane. This study introduces a new mixture of hybrid bioreactor membranes that combine oxidized multi-walled carbon nanotubes (OMWCNTs) with polyethersulfone (PES) using a phase inversion method, along with equal proportions of zinc oxide nanoparticles (ZnO NPs) and Arabic gum (AG) from an acacia tree, for application in a submerged membrane bioreactor to treat wastewater for a dairy product at the College of Agriculture / Baghdad University. The results when comparing the nascent composite membranes (PES / OMWCNTs / ZnO / AG) with that of (PES / OMWCNTs) indicated that the membrane mixed with ZnO / AG has more hydrophilic (16%) As well as reducing the negative charge on the surface of the membrane almost three times, As evidenced by the water contact angle test and the zeta potential data respectively, furthermore, the atomic force microscopy analysis showed that this improved membrane showed lower values of surface roughness (by 46.8%), and more flexible normal flux values (by almost doubling), Moreover, the rate of rejection increased when the bovine serum albumin (BSA) solution was passed a percentage (13%) when compared with PES / MWCNTs membrane. Importantly, the prepared membrane also presented removal efficiency of chemical oxygen demand (COD) was significantly 37.5% higher when compared with the commercial MBR system.

A pot experiment was carried out in the green house of Bangladesh Jute Research Institute (BJRI), Dhaka to study the response of jute (Corchorus capsularies and Corchorus olitorius) to the accumulation of As from soil to plants when various rates of As were applied. In the experiment, four treatments of arsenic (control, 10, 20 and 40 mg/kg) were applied. The salt sodium meta-arsenite (NaAsO2) was used as a source of As. Three jute varieties of CVL-1, 0-9897 and OM-1 were used.  CVL-1 variety is As sensitive whereas the 0-9897 and OM-1 varieties appeared to be As tolerant and OM-1 takes up the highest amount of As. Arsenic will be ingested into the body exceeding the maximum allowable daily limit (0.22mg/kg per day) through the consumption of 100g of jute leaves of these three varieties per day. Accumulation of As at 10 and 40 mg/kg treatment, the maximum was observed at 52 days harvest for CVL-1 while for the other two treatments, the maximum was observed at 42 days of growth. In the case of 0-9897 and OM-1 varieties, overall the maximum accumulation of As was observed at 42 days of growth at 40 mg/kg treatment.

A green approach was employed to fabricate ZSM-5 zeolite from expanded perlite and reduced graphene oxide (rGO) in the presence of the synthesized ZSM-5 zeolite to produce ZSM-5@rGO composite by one-step synthesis process via hydrothermal treatment. ZSM-5@rGO composites were characterized by various techniques such as scanning electron microscopy (SEM),  X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, Raman spectroscopy, and N2 desorption–adsorption. The results showed that ZSM-5@rGO composite have a large surface area, uniform distribution and orderly crystal form. Moreover, the synthesized composites were evaluated as an adsorbent for removing cationic dye, methylene blue (MB), from an aqueous solution. The influence of factors on the adsorption, such as adsorption time, adsorbent dosage, initial dye concentration, and pH of solution, were investigated. The results of isothermal adsorption showed that the adsorption process was fit for both Langmuir and Freundlich models, and the highest adsorption capacity of ZSM-5@rGO composite for MB dye was 95.87 mg/g at environment temperature (30 oC). In addition, the study of adsorption kinetics indicated that the adsorption was consistent with the pseudo-second-order kinetic model with correlation coefficients of 0.9962. From these results, it can be confirmed that ZSM-5@rGO composite uses silicoaluminate as economical starting material with relatively high adsorption capacity and removal efficiency, which is a promising application for treating wastewater on a large scale.

Fat, oil, and grease (FOG) deposits in the urban sewer system affect the optimal performance of the wastewater collection system and treatment plant, while increasing sewer maintenance costs. The interaction of microplastics (MPs) and FOG in the sewer system could drastically change the quality of deposited materials and the fate of MPs in raw sewage. In this study, the batch experiment was conducted to explain the mechanism of FOG formation by synthetic wastewater and its interaction with polystyrene (PS) and polymethyl methacrylate (PMMA) particles. We found three different segments for FOG deposits in the batch, namely static and buoyant micro-deposits, gel-like, and solid deposits. The average size of micro-deposits adhered to the solid-liquid interface of the container was 25 µm and buoyant deposits with a small size of 3 µm adsorbed onto the MPs at the liquid-air interface. The gel-like formation promoted a virtual liquid phase where PS and PMMA were confined and segregated. Some PMMA particles were entrapped in the self-assembly of biopolymers that formed between the PS particles. This research indicates that FOG deposition in the urban sewers contains high numbers of MPs, such that any plan involving a reuse or disposal program requires a risk assessment.