Avicenna Journal of Environmental Health Engineering
Volume:3 Issue: 1, Jun 2016

Cr (VI) as an extremely soluble and highly toxic ion is present in effluents of industries and imposes severe health-related problems. The current study aimed to provide information on Cr (VI) adsorption potential of fire clay as an abundant, cost-effective and untried material. Batch adsorption trials of Cr (VI) were performed to investigate the effects of pH, contact time, initial metal ion concentration and the adsorbent dosage. Langmuir, Freundlich and Dubinin–Radushkevich isotherm models were used to evaluate the equilibrium data at 20°C and regression coefficients were derived. Moreover, adsorption kinetics was analyzed using the pseudo-first-order and the pseudo-second-order kinetic models. Maximum chromium removal was found at pH 2.0. A kinetic study yielded an optimum equilibrium time of 90 minutes with an adsorbent dose of 2.5 g/50 mL. Results suggested that the equilibrium adsorption described by the Freundlich model. The kinetic data of the sorption showed that the pseudo second-order equation was the more appropriate. The results of the study indicated that fire clay was not a suitable adsorbent for Cr (IV). Apart from relatively long equilibrium time, the efficiency was not satisfactory. Therefore, searching for better alternative and/or modify such adsorbent is necessary in this area.

This paper evaluates the technical feasibility of reusing hemodialysis reverse osmosis wastewater from educational hospitals in Yazd, Iran, as an alternative water source. For this study, from October to December 2013, hemodialysis reverse osmosis wastewater samples were obtained from two dialysis facilities and analyzed for biochemical oxygen demand (BOD), chemical oxygen demand (COD), pH, and electrical conductivity (EC) using standard methods. Furthermore, concentrations of heavy metals such as Ag, Ba, Cd, Cu, Pb, Se, and Zn were calculated. Results were analyzed using the one sample t-test and independent t-test in SPSS 16 software. Mean concentrations of Ag, Ba, Cd, Cu, Fe, Pb, Se, and Zn in the hemodialysis reverse osmosis wastewater were 0.0960, 0.0611, 0.0186, 0.3381, 0.2153, 0.2212, 0.4196, and 0.0667 mg/L at S. Dr. Rahnamoon hospital, and 0.0963, 0.0849, 0.0177, 0.2942, 0.2160, 0.1827, 0.3420, and 0.0867 mg/L at S. Sadoughi hospital, respectively. The results also showed that the important challenges for reusing hemodialysis wastewater were its high EC and the presence of some elements, such as Se and Pb. Unlike Se and Pb, the concentrations of the other parameters were below discharge emission standards. Because of the large volumes of water used in hemodialysis, it is important to study the potential for reusing or recycling it. Through evaluation of the technical feasibility of hemodialysis wastewater reuse, this study draws attention to this neglected issue, especially in hemodialysis therapy.

Hospital wastewater is of great environmental concern because it contains a variety of hazardous microbial and chemical substances. This study aims to investigate the efficiency of a moving bed biofilm reactor (MBBR) with a light expanded clay aggregate (LECA) carrier for treating hospital wastewater. This pilot study used a Plexiglas reactor that had a volume of 100 L, a continuous up-flow hydraulic regime, and a LECA carrier to test removal of chemical oxygen demand (COD) from wastewater in a public hospital. To assess MBBR efficiency, the study used retention times of 8, 12, and 24 hours, filling percentages of 30% and 50%, and mixed liquor suspended solids (MLSSs) of 1000, 3000, and 5000 mg/L. The results indicated that using a single LECA carrier in an MBBR system was not sufficient to remove organic materials from hospital wastewater, because the carrier could not be completely suspended. After some modifications, consisting mainly of returning activated sludge, the system was 83% efficient at removing COD using a LECA carrier at a retention time of 24 hours, with 50% filling, and 5000 mg/L of MLSS.

Among various trihalomethane (THM) compounds, chloroform is considered to be the main compound and was selected as an indicator of THMs in this study. This study aims to calculate and assess the lifetime cancer risks resulting from chloroform intakes of various exposure routes in Ilam’s urban drinking water. The samples were analyzed using a gas chromatograph equipped with a flame ionization detector (GC/FID). The results showed that average chloroform concentrations in different districts were between 20 and 30.3 μg/L, and the highest concentrations were detected in district 4 with a value of 32.2 μg/L. All water samples contained concentrations of chloroform below the standards of the world health organization (WHO) and the institute of standards and industrial research of Iran (ISIRI). Assessment of lifetime cancer risks was carried out using prediction models for different exposure routes, including ingestion, inhalation, and dermal routes for people living in Ilam city. The highest risk from chloroform seems to be from the oral ingestion route, followed by inhalation and dermal absorption. The maximum and minimum lifetime cancer risks were 6.59 × 10 - 6 and 5.95 × 10 - 6 in districts 4 and 3, respectively. It was also concluded that the average lifetime cancer risk was 6.26 × 10 - 6 in all districts. Based on the population data, the total number of expected lifetime cancer cases from exposure to chloroform is 1 for Ilam city.

In this study, the mortality effects of commercial gasoline at different tested concentrations were evaluated on the common roach (Rutilus caspicus) and LC50 values for each time period (24, 48, 72, and 96 hours) have been determined.
Roach with an average weight of 3.1 ± 0.45 g and lengths of 4 ± 0.25 cm were used in this study. After transferring the 200 fish to the laboratory, they were kept in tanks of 100 liters for one week to adapt them to the experimental conditions. After the adaptation period, 100 fish were selected randomly and divided into 14 treatments (0, 2, 5, 10, 20, 40, 60, 80, 100, 200, 400, 600, 800, and 100 ppm commercial gasoline). The treatments were completed in triplicate.
The results of this study show that the 96-hour LC50 of commercial gasoline is 600.2 ± 0.44 ppm and the maximum allowable concentration (MAC) is 60.02 mg/L.
The study demonstrates the deadly effects of commercial gasoline on the Caspian roach. Spillage of diesel and gasoline fuels from transport tankers can enter rivers and eventually the marine ecosystem, and reach nursery and spawning areas where it can become a serious threat to fish survival.

Phenol is a toxic hydrocarbon that has been found in the wastewater of several industries, including the petroleum and petrochemical industries. The discharge of untreated wastewater from these industries causes environmental pollution, especially in water. The aim of this study was to evaluate the efficiency of phenol removal from wastewater using a biofiltration system. In this experimental study, a cylindrical plexiglass biofilter reactor with an effective volume of 12 liters was used. A total of 30 pcs of plastic grid discs were placed inside the reactor by plastic pipes to maintain the biofilm media in the reactor. The microorganisms used in this study were obtained from the biological sludge of a municipal wastewater treatment plant. The reproduction and adaptation of the microorganisms to 500 mg/L of phenol lasted three months. The effects of pH, phenol, nitrogen, phosphorus, glucose concentration, and hydraulic retention time on the biofilter system’s performance was evaluated. The results of this study showed that in optimal conditions, this system can reduce the phenol concentration from 500 mg/L to zero within about 4 hr. Maximum efficiency occurred in pH = 7, and the proper COD/N/P ratio was 100/10/2, respectively. In general, this biofilter system is capable of removing 500 mg/L of phenol concentrations and an organic load of 4 - 4.5 kg COD/m3.d within 4 - 5 hr. with high efficiency.

Landfill leachate presents hardly treatable, highly complex and very toxic environmental effluent originated in the municipal solid waste degradation process. Although, numerous treatment methods were developed so far, none of them alone could achieve permissible limits of the primary pollutants to discharge into natural recipients.
The current study aimed to develop and apply the process to treat landfill leachate by simultaneous application of electrochemical methods, ultrasound, electromagnetic field and ozonation to achieve the legal criteria for its discharge into natural recipient and minimize its adverse environmental impacts.
For this purpose, old landfill leachate was taken from the Piskornica (Koprivnica, Croatia) sanitary landfill. Prior to the treatment, the leachate was supplemented with NaCl (2 g/L) and subjected to simultaneous treatment with stainless steel electrode plates, ultrasound and recirculation through electromagnetic field. After 45 minutes, stainless steel electrode plates were replaced by iron electrodes and treated for another 10 minutes followed by 15 minutes of the treatment with aluminum electrode plates. Ultrasound and recirculation through electromagnetic field were also applied during Fe and Al electrode treatment. Finally, the electrodes were removed and the suspension was mixed with ozone for another 30 minutes and allowed to settle for an hour. Following the combined treatment, the removal efficiency for the turbidity, color, suspended solids, ammonium, phosphates and heavy metals was 99% or higher, while the removal of COD was 97%. All the measured parameters in the treated leachate were lower compared to upper permissible limit for discharge into natural recipient.

In this study, sodium dodecyl sulfate (SDS) coated magnetite modified with 2, 4-Dinitrophenylhydrazine was used to remove Cr (VI) ions from aqueous solution. The modified magnetite nanoparticles were characterized by X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and SEM–EDXS measurement. The synthesized nanoparticles exhibited a high surface area of 75.5 m2 g−1 and were of 20 - 35 nm in particle size. The effects of parameters, including pH, dose of adsorbent, temperature and contact time were investigated to find the optimum adsorption conditions. Adsorption data fits well with the Langmuir isotherm model with a maximum adsorption capacity (qm) and a Langmuir adsorption equilibrium constant (b) of 169.5 mg g-1 and 0.168 L mg-1, respectively. The adsorption kinetic agrees well with pseudo-second-order model.