Evaluation and analysis of gaseous emission in landfill area and estimation of its pollutants dispersion, [case of Rodan in Hormozgan, Iran]

Background: The biogases are the mixture of gases produced through the microbial decomposition of organic waste which are amply observed in the landfills. The main purpose of this study was to estimate the emission rates of landfill gases such as carbon dioxide, methane and non-methane organic compounds [NMOCs] in the solid waste landfill of Rodan city in Hormozgan province

Methods: All the necessary information such as population, geographic and climate of Rodan city were collected. Solid waste analysis was then conducted. Afterward, the LandGEM software is used in this study for the purpose of estimation of total biogas, methane, carbon dioxide and NMOCs emission from Rodan's landfill

Results: The analysis of results showed that only 24.18% of the produced waste in this city is perishable. The calculations indicate that the peak of biogas production which is equal to 420 tons per year would be achieved in the year 2019. The production rates of carbon dioxide and methane in the same year would be equal to 308 and 112 tons per year respectively. The pollutants transmittance calculations in the vicinity of the landfill revealed that the maximum pollutant concentration is within the maximum distance of 200 m

Conclusion: The results obtained in this study could be used for the purpose of design and installation of extraction or incineration equipment in the landfill of Rodan

Treatment of mature landfill leachate by chemical precipitation and Fenton advanced oxidation process

Background: Mature landfill leachate is a complicated mixture which is resistant to biological treatment processes. The treatment of mature landfill leachate by struvite precipitation and Fenton oxidation was the main objective of the current research

Methods: Struvite with the phosphate/ammonia/magnesium molar ratio of 1/1/1.05 was considered during all experiments. Five initial pHs of 3, 4, 5, 6, and 7, four different H[2] O[2]/Fe mass ratios of 50, 100, 200, and 400, and reaction times of 20, 40, 80, 120, and 160 minutes were examined for the Fenton oxidation process

Results: A leachate sample with average chemical oxygen demand [COD], BOD[5], and NH4 concentrations of 7350, 2220, and 2280 mg L[-1], respectively, and a BOD[5]/COD ratio of 0.3 was introduced to the chemical precipitation unit. An NH[4] removal efficiency of 87% was obtained at pH 8.5 for struvite precipitation. Under optimum conditions of Fenton oxidation, including pH 3, an H[2]O[2]/Fe[2 +] mass ratio of 200, and a reaction time of 160 min, more than 95% COD and BOD[5] removal was observed

Conclusion: Struvite precipitation and Fenton oxidation are reliable and efficient alternatives for mature landfill treatment

[Effects of biofilm in improvement of activated sludge efficiency for treatment of industrial effluents containing formaldehyde]

Formaldehyde is used in many industrial applications as raw material and therefore high concentrations are found in their effluents. Activated sludge processes based on biofilm growth are increasingly used because of appreciate abilities in controlling of high organic load industrial effluents. The main objective of this study was to determine the effect of biofilm in improvement of activated sludge efficiency for treatment of industrial effluents containing formaldehyde. Two lab scale activated sludge reactors [with and without fixed bed for biofilm growth] were investigated in organic loading rate of 0.7-10.5 kgCOD/m3.d, aerobic condition and the room temperature. In this study, the effects of organic and hydraulic loads were investigated for the mentioned two processes. The most COD removal efficiency for biofilm activated sludge was 98.86%. The reactor containing biofilm had removal efficiency of more than 64% up to the organic loading rate of 10.5 kgCOD/m3.d, while the conventional activated sludge reactor collapsed in organic loading rate of 7.5 kgCOD/m3.d. Findings of this study indicate that activated sludge reactor containing fixed bed for biofilm growth is significantly more efficient than the conventional activated sludge one

[Leachate treatment by batch decant activated sludge process and powdered activated carbon addition]

Direct biodegradation of landfill leachate is too difficult because of high concentrations of COD and NH3 and also the presence of toxic compounds. The main objective of this study was to application of Strurvite precipitation as a pretreatment stage, in order to remove inhibitors of biodegradation before the batch decant activated sludge process with addition of powdered activated carbon [PAC]. Strurvite precipitated leachate was introduced to a bench scale batch decant activated sludge reactor with hydraulic retention times of 6 and 12 hour. PAC was added to aeration tank directly at the rate of 3.5 g/L. TCOD, SCOD, NH3 and P removal efficiency with addition of PAC in HRT of 6 h were 90, 87, 98.3 and 94% respectively and 96, 95, 99.2 and 98.7 5 in HRT of 12 h. According to obtained data from this work, it can be concluded that Strurvite precipitation before batch decant activated sludge process and simultaneous addition of PAC is promising technology for leachate treatment and can meet effluent standards for discharge to the receiving waters