Organochlorine pesticides removal from groundwater by citrus coal and uv/o3: A hybrid pilot-scale study

In this laboratory-scale study, organochlorine pesticides (OCPs) reduction using citrus coals and O3 assisted by solar UV as an integrated treatment of groundwater under visible UV to reach sustainable development were traced. The experimental parameters were set up throughout standard methods and analysis protocols. The best performance of citrus coal was observed at a reaction time of 90 min, pH: 6.5, adsorption bed height = 40 cm, initial OCPs concentration, respectively, as 100 µg/L for alachlor (ALC), α (±)-BHC, atrazine (ATZ), and α-chlordane, 150 µg/L for methoxychlor, 50 µg/L for heptachlor, and 90 µg/L for dieldrin. The best performance of citrus coal was observed at a reaction time of 90 min, pH: 6.5, adsorption bed height 40 cm, initial OCPs concentration of 100 µg/L for ALC, α (±)-BHC, ATZ, and α-chlordane, 150 µg/L for methoxychlor, 50 µg/L for heptachlor, and 90 µg/L for dieldrin. Under the above-mentioned operating conditions, the removal rates were estimated at more than 75 for all these compounds. The adsorption outputs were fitted to the Freundlich model with the average R2 > 0.97, while for the Langmuir model this value was >0.86. Thereby, it is concluded that OCPs adsorption occurs on a heterogeneous surface by multilayer sorption. With regard to Kf (1/n) parameter, for the Freundlich adsorption model, the order of OCPs adsorption was appeared to be methoxychlor > dieldrin > heptachlor > α-chlordane > ALC > α (±)-BHC > ATZ. The optimum variables for UV/O3 were obtained as 0.4 mg/L ozone, pH = 9, and 35 min reaction time, so that, more than 98 of these substances were degraded from the solution under this condition. The reaction kinetics were fitted with R2 value of more than 0.9 for most OCPs. The kinetic reaction constants (k) in pH values of 7 and 9.5 were higher than other ranges for all OCPs. The progress of pH at the alkaline area improved the pseudo-first-order constants. The kinetic model indicated that the reaction rates will be restricted by the initial pH value and the concentration of OH�. This evidence was well-established by monitoring dissolved O2 at the various pH ranges during the experiment runs. Eight intermediates were detected by gas chromatography-tandem mass spectrometry detection with chemical formula as C14 H20 ClNO3, C13 H16 ClNO3, C14 H18 ClNO4, �NHCH(CH3 )2, �NHCOCH3, �NH2, C13 H9 ClO, and C7 H5 ClO from the samples taken in the non-optimized UV/O3 effluent. However, all of them disappeared in the final effluent at the optimized condition. Altogether, this integrated strategy helped to remove OCPs more than 86 on average, with residues less than 1 µg/L and even 0.05 µg/L in some cases. Due to the generation of a large amount of citrus wastes (46,000 ton/y) in the north of Iran and the abundance of solar energy especially solar UV in the middle east, this hybrid approach to treat groundwater contaminated with agricultural OCPs as a type of EDCs can be an effective alternative for conventional and current removal strategies to provide safety and treat groundwater by this agricultural compound. © 2021 Desalination Publications. All rights reserved

Electrochemical Degradation of Reactive Black 5 Using Three-Dimensional Electrochemical System Based on Multiwalled Carbon Nanotubes

The removal of Reactive Black 5 (RB5) dye and chemical oxygen demand (COD) was investigated using a three-dimensional (3D) electrochemical (3DE) reactor with multiwalled carbon nanotubes (MWCNTs). The experiments were performed according to a Taguchi design model, with the variables being the solution pH (2-9), current density (10-25 mA/cm2), reaction time (15-60 min), MWCNT concentration (25-200 mg/L), and RB5 concentration (25-100 mg/L). The best conditions for optimum removal of RB5 and COD were pH 3, MWCNT concentration 200 mg/L, current density 15 mA/cm2, RB5 concentration 100 mg/L, and reaction time 60 min. Among the main factors, the solution pH for removal of COD and RB5 and the current density for energy consumption had the highest impact. The 3D system generated more H2O2 and OH radicals compared with a two-dimensional (2D) system because the MWCNTs act as microelectrodes in the optimal conditions. In the 3D process, the production of high levels of reactive species led to an increase in the degradation of RB5 into aromatic compounds and various acids. © 2019 American Society of Civil Engineers

Removal behavior of gaseous furfural using a biofilter packed with perlite, ripe compost, and oak woodchips

Furfural is a toxic compound that is widely used in various industries. Prolonged inhalation exposure to this pollutant, especially at workplaces, can induce detrimental health effects. Therefore it is important to remove it from the environment. The present study aimed to investigate furfural removal from polluted air streams using a biofilter system. In this regard, a 4-section biofilter packed with perlite, ripe compost, and oak woodchips was operated for a 108 day-period under different operating conditions. The effects of pH (natural and acidic), inlet concentration (18.8�81.6 mg m�3), the height of biofilter layers (4 sections), and empty bed residence times (EBRTs) of 120, 70, and 30 s on removal efficiency (RE) of the biofilter were evaluated. All sampling and measurements were performed according to standard methods. The RE values under neutral and acidic conditions were 80 and 65 , respectively. At furfural inlet concentrations in the ranges of 18.8�21.3, 35.25�42.7, and 78.4�81.6 mg m�3, the RE values were 81, 68, and 57 , respectively. Also, the RE values at EBRTs of 120, 70, and 30 s were 83, 73, and 61 , respectively. About half of the total RE was related to the first section of the biofilter, where the number of bacterial (6.2 log10 CFU g-1) and fungal (5.8 log10 CFU g-1) were higher than the other sections. Due to the high RE (72 ) and low pressure drop (below 43 Pa m-1) of the biofilter, it can be concluded that biofiltration is a suitable process to remove furfural from the air. © 2020 Institution of Chemical Engineer

Removal behavior of gaseous furfural using a biofilter packed with perlite, ripe compost, and oak woodchips

Furfural is a toxic compound that is widely used in various industries. Prolonged inhalation exposure to this pollutant, especially at workplaces, can induce detrimental health effects. Therefore it is important to remove it from the environment. The present study aimed to investigate furfural removal from polluted air streams using a biofilter system. In this regard, a 4-section biofilter packed with perlite, ripe compost, and oak woodchips was operated for a 108 day-period under different operating conditions. The effects of pH (natural and acidic), inlet concentration (18.8�81.6 mg m�3), the height of biofilter layers (4 sections), and empty bed residence times (EBRTs) of 120, 70, and 30 s on removal efficiency (RE) of the biofilter were evaluated. All sampling and measurements were performed according to standard methods. The RE values under neutral and acidic conditions were 80 and 65 , respectively. At furfural inlet concentrations in the ranges of 18.8�21.3, 35.25�42.7, and 78.4�81.6 mg m�3, the RE values were 81, 68, and 57 , respectively. Also, the RE values at EBRTs of 120, 70, and 30 s were 83, 73, and 61 , respectively. About half of the total RE was related to the first section of the biofilter, where the number of bacterial (6.2 log10 CFU g-1) and fungal (5.8 log10 CFU g-1) were higher than the other sections. Due to the high RE (72 ) and low pressure drop (below 43 Pa m-1) of the biofilter, it can be concluded that biofiltration is a suitable process to remove furfural from the air. © 2020 Institution of Chemical Engineer

The concentration and probabilistic health risk assessment of nitrate in Iranian drinking water: a case study of Ilam city

In this study, the concentration of nitrate in 11 drinking water points in Ilam city was investigated, and furthermore, the consumer's probabilistic health risk was assessed. The nitrate levels in cumulative probability plot (CPD) of 50 (C-EXP50) and 95 (C-EXP95) were calculated as 8.12 and 16.37 mg/L, respectively, while in all samples (n = 77) were measured as significantly (rho value) lower than 50 mg/L (the proposed reference value by the World Health Organization (WHO) as well as Iranian national standard. Considering the probabilistic health risk; Hazard Quotient 50 (HQ(50)) and Hazard Quotient 95 (HQ(95)) were measured as 0.21 and 0.4, (HQ men > women. The health risk assessment shows that all consumers are safe of health risk

The concentration and probabilistic health risk assessment of nitrate in Iranian drinking water: a case study of Ilam city

In this study, the concentration of nitrate in 11 drinking water points in Ilam city was investigated, and furthermore, the consumer’s probabilistic health risk was assessed. The nitrate levels in cumulative probability plot (CPD) of 50 (CEXP50) and 95 (CEXP95) were calculated as 8.12 and 16.37 mg/L, respectively, while in all samples (n = 77) were measured as significantly (ρ value) lower than 50 mg/L (the proposed reference value by the World Health Organization (WHO) as well as Iranian national standard. Considering the probabilistic health risk; Hazard Quotient 50 (HQ50) and Hazard Quotient 95 (HQ95) were measured as 0.21 and 0.4, (HQ <1), respectively. Based on acceptable daily intake dose, HQ50s for men, women, and children were 0.09, 0.07, and 0.11 while HQ95s were 0.16, 0.12, and 0.22, respectively. Therefore, the order of the Hazard Quotients (HQ50 and HQ95) based on the age group of consumers was summarized as children > men > women. The health risk assessment shows that all consumers are safe of health risk. © 2019 Informa UK Limited, trading as Taylor & Francis Group