Degradation of azo dye Acid Red 14 (AR14) from aqueous solution using H2 O2 /nZVI and S2 O8 2- /nZVI processes in the presence of UV irradiation.

Azo dyes are mostly toxic and carcinogenic and cause harm to humans and the environment. This study was conducted to investigate the degradation of azo dye acid red 14 (AR14) from aqueous solution using hydrogen peroxide (H2 O2) /nano zerovalent iron (nZVI) and persulfate (S2 O8 2- )/nZVI processes in the presence of ultraviolet (UV) irradiation. This experimental study was carried out in a laboratory-scale batch photoreactor with a useful volume of 1 L. The nZVI was synthesized by the sodium borohydride (NaBH4 ) reduction method. In these processes, the effects of parameters including initial pH, H2 O2 concentration, S2 O8 2- concentration, nZVI dose, concentration of AR14 dye, and reaction time were studied. The results showed that decolorization increased by increasing the nZVI dosage, H2 O2 and S2 O4 2- concentrations, and reaction time, or decreasing dye concentration and pH. However, a too high oxidant concentration (H2 O2 and S2 O4 2- ) could inhibit the degradation. The experimental conditions for degradation of AR14 by UV/S2 O8 2- /nZVI and UV/H2 O2 /nZVI processes were as follows: [H2 O2 ] = 10 mM, [S2 O8 2- ] = 8 mM, AB14 dye = 100 mg/L, pH = 3, and nZVI dose = 0.05 g. Under these conditions, the highest removal efficiencies of AR14, chemical oxygen demand (COD), and total organic carbon (TOC) for the UV/S2 O8 2- /nZVI process were 93.94%, 86.5%, and 81.6%, respectively, while these values were 89.3%, 79.57%, and 72.9% for the UV/H2 O2 /nZVI, respectively. Also, the average oxidation state (AOS) was decreased from 2.93 to 2.14 in the effluent of the UV/S2 O8 2- /nZVI process and from 2.93 to 2.2 for the UV/H2 O2 /nZVI process. The results showed that the ratio of biochemical oxygen demand (BOD5 ) to COD in the effluents of the UV/S2 O8 2 /nZVI and UV/H2 O2 /nZVI processes after 90 min was 0.63 and 0.74, respectively. These findings suggest biodegradability improvement. PRACTITIONER POINTS: Photocatalytic degradation of azo dye Acid Red 14 (AR14) was achieved using H2 O2 /nZVI and S2 O8 2- /nZVI processes in the presence of UV irradiation. Effects of operating parameters on photocatalytic degradation AR14 dye were evaluated in the UV/H2 O2 /nZVI and UV/S2 O8 2- /nZVI processes. Biodegradability and mineralization studies of AR14 dye photocatalytic degradation were performed for the UV/H2 O2 /nZVI and UV/S2 O8 2- /nZVI processes.

Data on physicochemical quality of drinking water in the rural area in Divandarreh county, Kurdistan, Iran.

Good quality of drinking water is very important in the maintenance of human health. The gathered data from the present work was used to evaluate the quality of drinking water resources in the rural villages of Divandarreh, Iran. Physicochemical quality of water was determined by a collection of 35 random samples during dry and rainy seasons in 2015. The APHA approach was used to determine the physicochemical parameters of the samples. The results showed that the average concentration of Ca, Mg, Na, K, Cl, SO4, TDS and TH during dry season was 85.64 mg/l, 13.41 mg/l, 34.11 mg/l, 2.8 mg/l, 9.9 mg/l, 45.7 mg/l, 326.06 mg/l and 269.61 mg/l, respectively. Also, the average concentration of the parameters during rainy season was 77.3 mg/l, 18.27 mg/l, 30.3 mg/l, 1.9 mg/l, 12.54 mg/l, 39 mg/l, 269.1 mg/l and 316.17 mg/l, respectively.

Spatial distribution variation and probabilistic risk assessment of exposure to chromium in ground water supplies; a case study in the east of Iran.

A high concentration of chromium (VI) in groundwater can threaten the health of consumers. In this study, the concentration of chromium (VI) in 18 drinking water wells in Birjand, Iran, s was investigated over a period of two yearsNon-carcinogenic risk assessment, sensitivity, and uncertainty analysis as well as the most important variables in determining the non-carcinogenic risk for three age groups including children, teens, and adults, were performed using the Monte Carlo simulations technique. The northern and southern regions of the study area had the highest and lowest chromium concentrations, respectively. The chromium concentrations in 16.66% of the samples in an area of 604.79 km2 were more than World Health Organization (WHO) guideline (0.05 mg/L). The Moran's index analysis showed that the distribution of contamination is a cluster. The Hazard Index (HI) values for the children and teens groups were 1.02 and 2.02, respectively, which was more than 1. A sensitivity analysis indicated that the most important factor in calculating the HQ was the concentration of chromium in the consumed water. HQ values higher than 1 represent a high risk for the children group, which should be controlled by removing the chromium concentration of the drinking water.

Kinetics of biogas production and chemical oxygen demand removal from compost leachate in an anaerobic migrating blanket reactor.

In this study, laboratory anaerobic migrating blanket reactor (AMBR) with four units was used to reduce and remove COD leachate of composting process; it was also used to determine the kinetic coefficients of COD removal and biogas and methane gas production in several different OLRs. The maximum concentration of organic matter entering the reactor was 100,000 mg/L and the reactor was under operation for 319 days. The results showed that the COD removal efficiency of AMBR in all concentrations of substrate entering the reactor was above 80%. First-order model and Stover-Kincannon were used to investigate the kinetics of COD removal via AMBR biological process; in addition, the two models of Modified Stover-Kincannon and Van der Meer and Heertjes were used to check the kinetic constants of biogas and methane gas production. The results obtained from the models showed that the experimental data on COD removal were more consistent with the results obtained from Stover-Kincannon model (R2 = 0.999) rather than with the First-order model (R2 = 0.926). Kinetic constants calculated via Stover-Kincannon model were as follows: saturation value constant (KB) and maximum utilization rate constants (Umax), respectively, were 208,600 mg/L d and 172,400 mg/L d. We investigated the linear relationship between the experimental data and the values predicted by the models; as compared with the values predicted by the First-order model, the values predicted by Stover-Kincannon model were closer to the values measured via experiments. Based on the results of the evaluation of kinetic coefficients of Stover-Kincannon model, with the migration of the leachate flow from unit 1 to unit 4, Umax value has fallen significantly. The values of maximum specific biogas production rate (Gmax) and proportionality constant (GB) obtained from the Stover-Kincannon model, respectively, were 35,714 ml/L d and 42.85 (dimensionless) and value of kinetic constant of Van der Meer and Heertjes (ksg) was 0.0473 ml CH4/mg COD.

Decontamination of arsenic(V)-contained liquid phase utilizing Fe3O4/bone char nanocomposite encapsulated in chitosan biopolymer.

The application of a novel nanocomposite synthesized through the combination of Fe3O4 nanoparticles and bone char particles for the adsorption of As(V) ions in the aquatic medium was investigated. As-prepared nanocomposite was immobilized by using chitosan biopolymer. The characterization of the nanocomposite was performed via SEM, XRD, FT-IR, and BET together with the determination of zero-point charge of the adsorbent surface. As results, the obtained experimental data were fitted well with pseudo-first-order kinetic model (R2 = 0.997) and Langmuir isotherm model (R2 = 0.990) with the maximum adsorption capacity of about 112 µg/g. Increasing the dosage of nanocomposite and initial solute concentration led to increasing the adsorption capacity of As(V) ions, while decreasing the solution temperature resulted in the enhanced adsorption process. According to the results of thermodynamic study, the adsorption of As(V) ions onto the nanocomposite was spontaneous and exothermic in nature.