Evaluation of membrane bioreactor for hypersaline oily wastewater treatment

Produced water is a significant waste stream generated in association with oil and gas production. It contains high concentrations of hydrocarbon constituents and different salts. In this study, a membrane sequencing batch reactor (MSBR) was used to treat synthetic and real produced water. The MSBR was evaluated in terms of biodegradation of hydrocarbons in the synthetic produced water with various organic loading rates (OLR) (0.281, 0.563, 1.124, 2.248, and 3.372 kg COD/(m³ day)), cycle time (12, 24, and 48 h), and membrane performance. The effects of salt concentrations at different total dissolved solids (TDS) (35,000, 50,000, 100,000, 150,000, 200,000, and 250,000 mg/L) on biological treatment of the pollutants in the synthetic and real wastewater were studied. At an OLR of 1.124 kg COD/(m³ day), an HRT of 48 h and TDS of 35,000 mg/L, removal efficiencies of 97.5%, 97.2%, and 98.9% of COD, total organic carbon (TOC), and oil and grease (O&G), respectively were achieved. For the real produced water, removal rates of 86.2%, 90.8%, and 90% were obtained for the same conditions. However, with increasing salt content, the COD-removal efficiencies of the synthetic and real produced water were reduced to 90.4% and 17.7%, respectively at the highest TDS.     

Impacts of land use and land cover change on the interactions among multiple soil-dependent ecosystem services (case study: Jiroft plain,Iran)

The spatial and temporal distribution pattern is an outstanding feature of the relationship among ecosystem services (ESs) that explains links between human activities and disturbed chemical composition of ecosystems. This study investigated the spatiotemporal variation of land use/cover changes (LUCC) and quantifies the change in four essential ecosystem services with an emphasis on soil (nutrient delivery ratio, carbon storage, crop production, and water yield) and their relationships in the Jiroft plain, Iran, during 1996–2016 through analytical tools including Land Change Modeler, and the Integrated Valuation of Ecosystem Services and Tradeoff. During the 20-year concentrate period, there was a considerable overall gain in cropland (5396 km²) and urban (1787 km²), loss of unused land (5692 km²), water (2088 km²), and forest (1083 km²). As a result of LUCC, while crop production and nutrient delivery ratio showed a rising trend, overall carbon storage and water yield decreased. The spatiotemporal trade-off between carbon storage and crop production, the temporal trade-off between crop production and water yield, and synergy between water yield and crop production were widespread in Jiroft plain. These results showed that the interaction among ESs mutates over time and can be changed under planning and policies. This study will enrich the research of the geographical distribution of ESs interaction in dryland ecosystems to provide practical ecosystem management under local conditions.

     

Oxidative potential (OP) and mineralogy of iron ore particulate matter at the Gol-E-Gohar Mining and Industrial Facility (Iran)

Concentrations of total suspended particulate matter, particulate matter with aerodynamic diameter <2.5 μm (PM_2.5), particulate matter <10 μm (PM₁₀), and fallout dust were measured at the Iranian Gol-E-Gohar Mining and Industrial Facility. Samples were characterized in terms of mineralogy, morphology, and oxidative potential. Results show that indoor samples exceeded the 24-h PM_2.5 and PM₁₀ mass concentration limits (35 and 150 µg m^?3, respectively) set by the US National Ambient Air Quality Standards. Calcite, magnetite, tremolite, pyrite, talc, and clay minerals such as kaolinite, vermiculite, and illite are the major phases of the iron ore PM. Accessory minerals are quartz, dolomite, hematite, actinolite, biotite, albite, nimite, laumontite, diopside, and muscovite. The scanning electron microscope structure of fibrous-elongated minerals revealed individual fibers in the range of 1.5 nm to 71.65 µm in length and 0.2 nm to 3.7 µm in diameter. The presence of minerals related to respiratory diseases, such as talc, crystalline silica, and needle-shaped minerals like amphibole asbestos (tremolite and actinolite), strongly suggests the need for detailed health-based studies in the region. The particulate samples show low to medium oxidative potential per unit of mass, in relation to an urban road side control, being more reactive with ascorbate than with glutathione or urate. However, the PM oxidative potential per volume of air is exceptionally high, confirming that the workers are exposed to a considerable oxidative environment. PM released by iron ore mining and processing activities should be considered a potential health risk to the mine workers and nearby employees, and strategies to combat the issue are suggested.     

The implementation of data reconciliation for evaluating a full-scale petrochemical wastewater treatment plant

Data reconciliation and mass balance analysis were conducted for the first time to improve the data obtained from a petrochemical wastewater treatment plant (WWTP), and the results were applied to evaluate the performance of the plant. Daily average values for 209 days from the inlet and outlet of the plant obtained from WWTP documentation center along with the results of four sampling runs in this work were used for data reconciliation and performance evaluation of the plant. Results showed that standard deviation and relative errors in the balanced data of each measurement decreased, especially for the process wastewater from 24.5 to 8.6 % for flow and 24.5 to 1.5 % for chemical oxygen demand (COD). The errors of measured data were −137 m³/day (−4.41 %) and 281 kg/day (7.92 %) for flow and COD, respectively. According to the balanced data, the removal rates of COD and 5-day biological oxygen demand (BOD₅) through the aeration unit were equal to 37 and 46 %, respectively. In addition, the COD and BOD₅ concentrations were reduced by about 61.9 % (2137 kg/day) and 78.1 % (1976 kg/day), respectively, prior to the biological process. At the same time, the removal rates of benzene, toluene, and styrene were 56, 38, and 69 %, respectively. The results revealed that about 40 % of influent benzene (75.5 kg/day) is emitted to the ambient air at the overhead of the equalization basin. It can be concluded that the volatilization of organic compounds is the basic mechanism for the removal of volatile organic compounds (VOCs) and it corresponds to the main part of total COD removal from the WWTP.

     

Effect of low-density polyethylene on smoke emissions from burning of simulated debris piles

Low-density polyethylene (LDPE) plastic is used to keep piled debris from silvicultural activities—activities associated with development and care of forests—dry to enable efficient disposal by burning. The effects of inclusion of LDPE in this manner on smoke emissions are not well known. In a combustion laboratory experiment, 2-kg mixtures of LDPE and manzanita (Arctostaphylos sp.) wood containing 0, 0.25, and 2.5% LDPE by mass were burned. Gaseous and particulate emissions were sampled in real time during the entire flaming, mixed combustion phase—when the flaming and smoldering phases are present at the same time—and during a portion of the smoldering phase. Analysis of variance was used to test significance of modified combustion efficiency (MCE)—the ratio of concentrations of fire-integrated excess CO₂ to CO₂ plus CO—and LDPE content on measured individual compounds. MCE ranged between 0.983 and 0.993, indicating that combustion was primarily flaming; MCE was seldom significant as a covariate. Of the 195 compounds identified in the smoke emissions, only the emission factor (EF) of 3M-octane showed an increase with increasing LDPE content. Inclusion of LDPE had an effect on EFs of pyrene and fluoranthene, but no statistical evidence of a linear trend was found. Particulate emission factors showed a marginally significant linear relationship with MCE (0.05 < P-value < 0.10). Based on the results of the current and previous studies and literature reviews, the inclusion of small mass proportions of LDPE in piled silvicultural debris does not appear to change the emissions produced when low-moisture-content wood is burned. In general, combustion of wet piles results in lower MCEs and consequently higher levels of emissions.

Implications:Current air quality regulations permit the use of burning to dispose of silvicultural piles; however, inclusion of low-density polyethyelene (LDPE) plastic in silvicultural piles can result in a designation of the pile as waste. Waste burning is not permitted in many areas, and there is also concern that inclusion of LDPE leads to toxic air emissions.     

The effect of size and sex on PCB and PAH concentrations in crab Portunus pelagicus

Polychlorinated biphenyl and polycyclic aromatic hydrocarbon concentrations in the hepatopancreas of blue swimming crab (Portunus pelagicus) from the north Persian Gulf were measured. In addition, the relationships between crab size (carapace width) and polychlorinated biphenyl (PCB) and polycyclic aromatic hydrocarbon (PAH) levels in hepatopancreas were investigated by linear regression analysis. Among the PCBs, congeners 110 and 153 were the most frequent and abundant. The results showed that, except in a few cases, significant relationships between PCB and PAH levels and crab size were positive. Comparison between male and female indicated that the average PCB16, 44, 153, and acenaphthylene, acenaphthene, and anthracene concentrations in hepatopancreas of male crab were found to be significantly higher than those found in the female crab.     

Water and waste load allocation in rivers with emphasis on agricultural return flows: application of fractional factorial analysis

In this paper, a new methodology is developed to handle parameter and input uncertainties in water and waste load allocation (WWLA) in rivers by using factorial interval optimization and the Soil, Water, Atmosphere, and Plant (SWAP) simulation model. A fractional factorial analysis is utilized to provide detailed effects of uncertain parameters and their interaction on the optimization model outputs. The number of required optimizations in a fractional factorial analysis can be much less than a complete sensitivity analysis. The most important uncertain inputs and parameters can be also selected using a fractional factorial analysis. The uncertainty of the selected inputs and parameters should be incorporated real time water and waste load allocation. The proposed methodology utilizes the SWAP simulation model to estimate the quantity and quality of each agricultural return flow based on the allocated water quantity and quality. In order to control the pollution loads of agricultural dischargers, it is assumed that a part of their return flows can be diverted to evaporation ponds. Results of applying the methodology to the Dez River system in the southwestern part of Iran show its effectiveness and applicability for simultaneous water and waste load allocation in rivers. It is shown that in our case study, the number of required optimizations in the fractional factorial analysis can be reduced from 64 to 16. Analysis of the interactive effects of uncertainties indicates that in a low flow condition, the upstream water quality would have a significant effect on the total benefit of the system.     

Monitoring of trace amounts of heavy metals in different food and water samples by flame atomic absorption spectrophotometer after preconcentration by amine-functionalized graphene nanosheet

We are introducing graphene oxide modified with amine groups as a new solid phase for extraction of heavy metal ions including cadmium(II), copper(II), nickel(II), zinc(II), and lead(II). Effects of pH value, flow rates, type, concentration, and volume of the eluent, breakthrough volume, and the effect of potentially interfering ions were studied. Under optimized conditions, the extraction efficiency is >97 %, the limit of detections are 0.03, 0.05, 0.2, 0.1, and 1 μg L^?1 for the ions of cadmium, copper, nickel, zinc, and lead, respectively, and the adsorption capacities for these ions are 178, 142, 110, 125, and 210 mg g^?1. The amino-functionalized graphene oxide was characterized by thermogravimetric analysis, transmission electron microscopy, scanning electron microscopy, and Fourier transform infrared spectrometry. The proposed method was successfully applied in the analysis of environmental water and food samples. Good spiked recoveries over the range of 95.8–100.0 % were obtained. This work not only proposes a useful method for sample preconcentration but also reveals the great potential of modified graphene as an excellent sorbent material in analytical processes.