Petrochemical waste characterization and management at Pars Special Economic Energy Zone in the south of Iran.

Industrial waste management generated by different petrochemical complexes at Pars Special Economic Energy Zone, located in the south of Iran, was investigated. All 10 active petrochemical complexes were visited and generated wastes were identified by a checklist. Petrochemical plants were classified regarding feeds, process, and products and nine representative wastes were sampled. Physicochemical characteristics were analyzed and appropriate management approaches were proposed according to the literature review and the results of waste characterization. The generated wastes were classified as hazardous and non-hazardous according to the Basel Convention and Environmental Protection Agency lists of waste classification. Also, the concentrations of organic compounds and heavy metals were measured to classify wastes characteristically. Comparing concentrations of the most important heavy metals in sampled wastes illustrated that sandblast with Cu concentration of 4295 mg kg-1, spent activated carbon with Hg concentration of 127 mg kg-1, and spent catalyst with 25% Ni content can be categorized as hazardous wastes, due to the exceeding Total Threshold Limit Concentration levels. Based on laboratory results, all industrial waste generated in the petrochemical complexes were categorized into three groups, namely Organic Waste with High Calorific Value, Non-organic Recyclable Waste, and Non-organic Non-recyclable Waste. Finally, management approaches, including material recycling, energy recovery (through incineration), and landfilling, were proposed and a conceptual model was suggested in order to show different routes and final destination for each kind of waste generated in all similar petrochemical complexes.

Interaction of graphene oxide nano-sheets and landfill leachate bacterial culture.

The interaction of graphene oxide (GO) and municipal landfill leachate bacterial culture was investigated. In aerobic conditions, stepwise addition of GO concentration to 60 mg/L increased the oxygen uptake rate coefficient. However, increasing the GO concentration to 100 mg/L slightly decreased the oxygen uptake rate coefficient. When anoxic conditions developed, GO suspensions decreased the total bacterial activity and the substrate consumption. Raman spectroscopy confirmed the chemical reduction of GO during exposure to bacteria; nonetheless, the extent of reduction in anoxic conditions was more than that in aerobic conditions. The chemical composition of landfill leachate showed to be able to also slightly reduce the GO after 10 days exposure, but the role of bacterial activity in the reduction process seemed to be dominant. As far as it could be seen under a light microscope, while the gram-positive bacteria were more vulnerable in anoxic assays, GO suspension did not affect the morphology and size of active cultures in the aerobic atmosphere.

A performance-based method for calculating the design thickness of compacted clay liners exposed to high strength leachate under simulated landfill conditions.

Compacted clay liners (CCLs) when feasible, are preferred to composite geosynthetic liners. The thickness of CCLs is typically prescribed by each country's environmental protection regulations. However, considering the fact that construction of CCLs represents a significant portion of overall landfill construction costs; a performance based design of liner thickness would be preferable to 'one size fits all' prescriptive standards. In this study researchers analyzed the hydraulic behaviour of a compacted clayey soil in three laboratory pilot scale columns exposed to high strength leachate under simulated landfill conditions. The temperature of the simulated CCL at the surface was maintained at 40 ± 2 °C and a vertical pressure of 250 kPa was applied to the soil through a gravel layer on top of the 50 cm thick CCL where high strength fresh leachate was circulated at heads of 15 and 30 cm simulating the flow over the CCL. Inverse modelling using HYDRUS-1D indicated that the hydraulic conductivity after 180 days was decreased about three orders of magnitude in comparison with the values measured prior to the experiment. A number of scenarios of different leachate heads and persistence time were considered and saturation depth of the CCL was predicted through modelling. Under a typical leachate head of 30 cm, the saturation depth was predicted to be less than 60 cm for a persistence time of 3 years. This approach can be generalized to estimate an effective thickness of a CCL instead of using prescribed values, which may be conservatively overdesigned and thus unduly costly.

Removal of manganese and zinc from Kahrizak landfill leachate using daily cover soil and lime.

The possibility of in situ removal of heavy metals found in leachate generated at municipal solid waste landfills was studied through amendment of daily cover soil. Kahrizak landfill, which receives the waste generated at Tehran, was selected as the source of leachate and soil samples. Manganese and zinc were selected in this study. The soil sample taken from the Kahrizak site contained about 17% clay, which was presumed to have significant capability for removing manganese and zinc. This capability was assumed to be enhanced further through the addition of lime and consequently to improve the potential for chemical precipitation of the selected metals. The in situ removal experiment was accomplished through a set of seven columns filled with the sampled soil with varying contents of lime (i.e., from 0% to 6% by dry weight). Fresh leachate of low pH was added to the columns on a daily basis. Concentrations of manganese and zinc were measured in the influent and effluent during 40 days when biological clogging resulted in a condition of almost no outflow in the columns. The results indicated a substantial increase in removal efficiency through the addition of lime to the daily cover soil. Desorption resulting from the low pH of fresh leachate occurs at later stages compared to the column with no lime addition.