Avicenna Journal of Environmental Health Engineering
Volume:6 Issue: 1, Jun 2019

Landfill leachate is highly polluted and generated as a result of water infiltration through solid waste produced domestically and industrially. This study investigated the applicability of the response surface methodology (RSM) to optimize the removal performances of chemical oxygen demand (COD), color, and suspended solids (SS) from landfill leachate by coagulation process using Tin tetrachloride pentahydrate. The leachate samples were collected from Alor Pongsu Landfill (APLS) in Perak, Malaysia. Before starting the experiments, general characterization was carried out for raw leachate samples to investigate their physical and chemical properties. The effects of the dosage and pH of SnCl4 on the removal performances were evaluated as well. An ideal experimental design was performed based on the central composite design (CCD) by RSM. In addition, this RSM was used to evaluate the effects of process variables and their interaction toward the attainment of their optimum conditions. The statistical design of the experiments and data analysis was resolved using the Design-Expert software. Further, the range of coagulant dosage and pH was selected based on a batch study which was conducted at 13000 mg/L to 17000 mg/L of SnCl4 and pH ranged from 6 to 10. The results showed that the optimum pH and dosage of SnCl4 were 7.17 and 15 g/L, respectively, where the maximum removal efficiency was 67.7% for COD and 100% for color and SS. The results were in agreement with the experimental data with a maximum removal efficiency of 67.84 %, 98.6 %, and 99.3%, for COD, color, and SS, respectively. Overall, this study verified that the RSM method was viable for optimizing the operational condition of the coagulation-flocculation process.

Hazardous wastes include numerous kinds of discarded chemicals and other wastes generated from industrial, commercial, and institutional activities. Because of the complexity of waste management systems, the selection of the appropriate solid waste landfill site requires consideration of multiple alternative solutions and evaluation criteria. Based on actual conditions of the study area, we considered economic, biological and topographical factors (12 criteria). This paper investigated the use of the Fuzzy logic in combination with Analytic Hierarchy Process (AHP) method by applying GIS and IDRISI software for the selection of a hazardous waste landfill site in the Iranian province of Hamedan. The candidate sites were determined by aggregation based on the criteria weights. The best location was determined via the Fuzzy and the AHP methodologies. By collating the area selected for the hazardous waste landfill, this study found that Fuzzy logic with AHP methodologies had the best options for this purpose. In the end, 6 suitable area for a hazardous waste landfill was were selected in Nahvand town. The combination of AHP method with Fuzzy logic using GIS in our experiment proves it is a powerful tool for solid waste landfill site selection.

The derivatives of phenols are among the most widely used chemicals in day-to-day life, which lead to water contamination by chlorophenols (CPs). These compounds belong to a class of those widely used chemicals that increase global concern about environmental protection due to their recalcitrant nature. Adsorption process has been employed for the removal of CPs from contaminated water out of many methods of wastewater treatment. This is due to its insensitivity to toxic substances, effectiveness, universal nature, fast kinetics, as well as the ease of operation and its simplicity in the design and applicability. Thus, this study compared the adsorption isotherm models such as linear and nonlinear and well discussed the fundamental characteristics, modelling, and mathematical derivations. Finally, the study highlighted and addressed the role of different isotherm models that were used in describing the adsorptive removal of CPs using various adsorbents.

This research mainly aimed to investigate phosphorus removal from stabilization pond effluent by using anionic resins in the continuous flow mode of operation due to high amounts of phosphorus in the wastewater treatment plant effluent of Kaboodrahang, western Iran, as well as the violation from a prescribed effluent standard to discharge receiving the surface waters. For this purpose, the pilot was made of a plexiglass cylinder and other equipment such as pump and other accessories, as well as Purolite A-100 resin. The reactor effects on the desired study parameters were assessed in two warm and cold seasons. The results showed that the phosphorus concentrations reduced from 7-10 mg/L to 4-7 mg/L and the rate of phosphorus removal was higher in the hot season compared to the cold season. Moreover, the optimum temperature and pH were obtained 21ºC and 8.5, respectively. The mean inlet biological oxygen demand (BOD) was 150 mg/L for both warm and cold seasons, where the highest removal rate of 17% was obtained in the cold season. The mean chemical oxygen demand concentration of the pilot was 250 mg/L for both seasons, and the highest removal rate was observed in the cold season with an efficiency of 18%. Regarding the total suspended solids with the mean inlet of 230 mg/L, the highest removal efficiency was obtained 6% in the warm season.

In this study, qualitative characteristics of the sludge produced in Hamadan wastewater treatment plant and the feasibility of its application in agricultural lands were investigated. Samples were taken from the primary and secondary sludge and indices such as VS/TS, PH, TKN, COD, TKN, SOUR, Na, Ca, SAR, heavy metals and biological properties (the mean fecal coliform count and the number of parasitic eggs) were measured. The results were compared with the United States Environmental Protection Agency (US EPA) standards (40 FCR-503). The results showed that the VS/TS ratio of the raw sludge was 0.8, 0.55, and 0.55 and that of the secondary sludge was 0.65, 0.28, and 0.32 for fall, winter, and summer, respectively. The average concentration of COD, TKN, SOUR, Na, and Ca for the initial sludge was 51283, 107, 0.50, 609, and 952 and for secondary sludge, it was 35595, 81, 4.90, 306, and 493 mg/L, respectively. The MPN for primary and secondary sludge was determined to be 19.83 × 106 and 186 × 106 , respectively and the average number of parasite eggs in primary and secondary sludge was 7.05 and 7.2 in 4 g of dry solids. Entamoeba coli had the highest number of parasite. The results of this study showed that the highest concentration of heavy metals in the sludge was 21396 mg/kg. The values obtained for the above-mentioned indices and heavy metals were in standards range. The results of this study show that none of the primary and secondary sludge samples has been properly stabilized. The values obtained for biological characteristics of sludge were not in the standard range. Therefore, it was revealed that the use of sludge for agriculture needed more stabilization.

Today, finding suitable methods to decrease plant abiotic stress such as heavy metals or salinity is very necessary in arid and semi-arid regions. Thus, this research was conducted as a factorial experiment in the layout of a completely randomized block design to evaluate the role of Piriformospora indica fungus and multi-walled carbon nanotubes (MWCNTs) on decreasing plant abiotic stress in the soil treated with lead (Pb)-polluted sewage sludge. The treatment consisted of applying sewage sludge at the rates of 0, 15, and 30 t/ha, 3 levels of cadmium spiked in to the applied sewage sludge (0, 800 and 1600 mg Pb/kg), as well as 0%, 0.5%, and 1.5% (W/W) MWCNTs in the presence and absence of P. indica. The plant used in this experiment was barely. After 90 days of the experiment, the plant was harvested and its Pb concentration was measured using atomic absorption spectroscopy. Applying 0.5 and 1% (W/W) MWCNTs in the soil treated with 15 t/ha sewage sludge significantly decreased plant Pb concentration by 8.1% and 12.3%, respectively. In addition, the presence of P. indica had significant effects on decreasing plant Pb concentration since the lowest plant Pb concentration was observed in soil amended with 30 t/ha sewage sludge (800 mg Pb/kg) by receiving 1.5% (W/W) MWCNTs in the presence of P. indica. The results of this study showed that applying MWCNTs has significant effects on decreasing soil heavy metals or soil salinity that is a positive point in environmental studies.

Global waste generation has been a challenging issue affecting humans and the environment. The conversion of vast amount of agricultural and polymeric waste to briquette may bridge the energy deficit and environmental pollution issues in developing economies. On the other hand, the utilization of biomass waste or residue as energy source could help alleviate dependence on imported energy and its use continues to be a topical issue in both developing and developed countries. Over the years, biomass has been an important source of generating energy due to its relative availability and the ability to meet both heat and electricity demand by contributing towards international commitments so as to minimize environmental degradation and maximize environmental, social and economic sustainability. The benefits of compacted biomass compared to all other types of biofuel include its low transportation and storage costs, uniform product quality such as constant humidity content and high mass fluency. Moreover, fuel wood and biomass residues have low combustion efficiency, also posing environmental and health hazards. This research studies the performance of briquettes produced from maize cob, sugarcane bagasse and polythene waste composites. The briquettes were agglomerated using cassava starch binder (CSB) and plantain peel binder (PPB) at binder concentrations 4%, 12% and 20%. Each briquette was characterized in terms of proximate analysis, calorific value ultimate analysis and micro-structure by Scanning Electron Microscopy. The briquettes contained moisture content 5.39-12.10%, volatile matter 10.15-23.08%, ash content 10.29-24.63%, fixed carbon content 55.84-77.10%, calorific value 9.04-28.14 MJ/kg, carbon content 77%-8405%, nitrogen content 0.875-1.05% and sulphur content 0.4-0.7%. The result from this study reveals that briquette with CSB at 4% binder concentration had the best properties required for biomass fuel briquette than that of PPB and suggests its use for the production of environmentally friendly solid fuel.

In the present study, magnesium oxide/granular activated carbon (MgO/GAC) composite as a catalyst was synthesized using the sol-gel method and its catalytic potential was investigated in the presence of ultraviolet (UV) irradiation for the removal of cephalexin (CLX) in a batch mode reactor. Then, the characterization of the MgO/GAC composite was determined by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Next, the effect of operational parameters was evaluated, including the pH of the solution (3-11), the dosage of composite (1-6 g/L), initial CLX concentration (20-100 mg/L), and contact time (10-60 minutes). The maximum CLX degradation with an initial concentration of 20 mg/L was as high as 98% at pH=3, 4 g/L of MgO/GAC composite with UV irradiation within 60-minute contact time. In addition, the removal process of CLX could be described by the pseudofirst-order kinetic. Further, the chemical oxygen demand (COD) and total organic carbon (TOC) removal rate were 78% and, 62.3% in optimum conditions, respectively. The results indicated that the UV/MgO/GAC hybrid photocatalytic process can be considered as an efficient alternative for treating the wastewater containing CLX.