Background and Objectives: Owing to the non-seperated municipal solid wastes the leachate form in land fills contain high amounts of heavy metalls and toxic substances Hence, leachate treatment is a serious problem. In order to design leachate treatment and collection systems, estimation of quality and quantity of leachate is of high necessity. Hydrologic Evaluation of Landfill Performance (HELP) Model was used to estimate leachate generation in the lined landfill cells for a variety of conditions. The HELP program is a quasi-two-dimensional hydrologic model for conducting water balance analysis of landfills, cover systems, and other solid waste containment facilities. In this paper HELP program is used to predict leachate generating in Semnan landfill after its operational life.Materials andMethods: HELPmodel useweather, soil and design data to estimate leachate quantity.The meteorological data were obtained from semnan Atmospheric Data Centre. Soil mechanics examinations in the landfill area were applied to achieve soil data. In addition, design parameters were based on Semnan landfill design specifications. Semnan landfill capacity is designed so as to accommodate municipal solid wastes generated during the next 25 years.Results: In this study result indicated that precipitation and evapotranspiration has the most influenced on leachate generation increase and decrease, respectively.82% of annual precipitation isn.t percolated into Semnan landfill due to evapotranspiration. HELP Model simulations were indicated that the maximum and average value of leachate height above barrier layer is 36 and 3mm, respectively.Conclusion: Semnan landfill is designed under minimum standard condition. Therefore, low height of leachate generated is due to area weather. The precipitation amount is low while the evapotranspiration amount is high in this area. High evapotranspiration is due to high temperature and solar radiation in Semnan landfill area. High evapotranspiration in the landfill cap caused 14.2% of the precipitation to infiltrate into the wastes and became leachate.

Degradation of the organic part of landfill in along with rainwater percolation produces a polluted liquid named "leachate", which poses a considerable hazard to the environment because of its toxic and hazardous compounds. In this research, the treatability of leachate was investigated using combined anaerobic digesters. Each digester had an effective volume of 150 l, a flow rate of 10 l/d, and a HRT of 15 d working at a temperature of 31oC (mesophilic). The OLR applied to the system was gradually increased from 0.07 to 3.4 g/l.d in 5 steps. TCOD concentration was 48552-62150.4 mg/l and BOD5/COD ratio was more than 0.7 during the study period. At an OLR of 2.2 g/l.d, the total maximum COD removal efficiency achieved in both digesters was 93.59%. Not only did ammonia concentration not reduce in the anaerobic system but it increased. Ammonia concentrations at optimum OLR in the influent to the 1st and 2nd digesters were 721, 952, and 1054 mg/l, respectively. Maximum biogas production was 9.823 l/day in the 1st digester and 6.298 l/day in the 2nd digester, both of which occurred at an OLR of 3.4 g/l.d.

Background and Aim: The solid waste in landfill is transformed into landfill gas during a biochemical conversion process called bio-degradation. Landfill gas is a product of waste decomposition containing 40 to 60 percent of methane and various amounts of other gases. The present project aims to estimate the proportion of environmental gases of Landfill No. 1 in Shahin Shahr (total landfill gas, methane gas and carbon dioxide gas), compare gas emissions over a 30 year period, and assess the capacity of the landfill for energy extraction. Materials and Methods: The field of research was Landfill No. 1 at Shahin Shahr Recycling Plant (Isfahan) located in Ja’ farabad Mountains, whose capacity was completed in 2010 and landfill gas assessment was carried out. The total amount of produced gases including methane and carbon dioxide was calculated using the first-order degradation model over a 30 year period. The proportions of these gases in Landfill were calculated from 2013 to 2043. Results: The results show that the amount of landfill gases production declined over the time. The maximum production of methane and carbon dioxide was about 350 and 950 thousand kilograms in 2013 and the minimum production of methane and carbon dioxide is estimated about 57 and 157 thousand kilograms, respectively, in 2043. The total volume of gases produced in this landfill has been estimated to be about 15 million cubic meters in 30 years, of which 27 percent is methane and 73 percent is carbon dioxide. The amount of methane and carbon dioxide gas is estimated to be about 5 million and 13 million kilograms in 30 years, respectivel. Conclusion: Generally, the landfill gases production declined over the time. It is recommended to use energy recovery technologies for controlling greenhouse gas emissions and generation of required energy for the ShahinShahr recycling plant in order to use this volume of gas.

Background: Landfilling is the most common way of municipal solid waste (MSW) disposal in Iran. Many countries have targeted landfill methane recovery among greenhouse gas mitigation strategies, since methane is the second most important greenhouse gas after carbon dioxide. Major questions remain with respect to actual methane production rates in field settings as well as the relative mass of methane that is recovered, emitted, oxidized by methanotrophic bacteria, laterally migrated, or temporarily stored within the landfill volume. Landfill gas (LFG) consists of 50% - 60 vol% methane and 30% - 40 vol% carbon dioxide as well as trace amounts of numerous chemical compounds such as aromatics, chlorinated organic compounds and sulfur compounds. Landfill methane outreach program (LMOP) is a voluntary assistance program which helps reduce methane emissions from landfills by encouraging the recovery and the beneficial use of LFG as an energy resource.Objectives: In this study, the volume of LFG of Tehran by landfill methane outreach program (LMOP) software was calculated. In addition, the relationship between the time of gas collection system operation and the volume of LFG production was evaluated.Materials and Methods: The LMOP software was used. The available information and some presumptions were used to operate the software. The composition of the solid waste collected from the landfill of Tehran had specific details. A large amount of it was organic materials, which was about 67.8%. These materials have a good potential to produce gas. In addition, LMOP Colombia model uses the first-order equations in all the analytical equations. Furthermore, it is assumed that the landfill operation time is 30 years and the process is considered in two conditions; first, the gas was recovered in 2000, and second, the process started in 2015.Results: The modeling results showed that for the gas recovery starting in 2000 and 2015, the power generation would be 2,354 and 830 MW, respectively. In fact, the 15-year difference in gas extraction made a 200% difference. Based on the results, from 2000 to 2100, 558 m3/hour of methane would be extracted, which would be equivalent to 2,354 MW energy. Subsequently, the emission of 93,721,837 tons of CO2 would be prohibited.Conclusions: It was observed that 2.8 times more energy was generated when the collecting system was initially installed. Moreover, if so, the equivalent CO2 was reduced by 60,695,377 ton. In fact, this process has economic and environmental benefits and the money will be saved and the emission will be controlled.

A landfill is a location designed for systematic long-term storage of waste under the conditions that it will prevent contamination of air and water. Landfill gas is produced by bacterial decomposition, which occurs when organic waste is broken down by the bacteria naturally present in the waste and in the soil used to cover the landfill. Landfill gas is composed of a mixture of hundreds of different gases. By volume, in general the landfill gas typically contains 45% to 60% methane and 40% to 60% carbon dioxide. This study has estimated total produced gas, carbon dioxide and methane, by the basic first-order decay model for Aradkooh Landfill till the next 30 years after the landfill is closed. Gas production has decreasing trend in time, as the maximum gas production for methane and carbon dioxide is in order of 6 and it will be 16 million kg in the year 2015.The minimum contribution will also be in order of 0.3 and 0.8 million kg in 2044. The total produced gas in the 30 years is 213 million m3 which 27% of its mass belongs to methane and 73% is carbon dioxide gas. In addition, the amount of methane, carbon dioxide and sulfur dioxide contributed from energy generation technology is calculated for 30 years and compared. The results show that the emission rate of controlled carbon dioxide gas is 1.85 times in uncontrolled state and the emission of controlled methane gas is 0.15 in uncontrolled state. In addition, using energy generation technology leads to sulfur dioxide contribution. The estimation for total amount of this gas in 30 years is predicted about 361 kg. Finally, the gases emissions predicted from this model are validated using the mass balance method according to other studies. Comparison of results shows good agreement with other studies.

Landfilling is an ultimate fate of any municipal solid waste management system, and it is a no alternative choice for disposal of municipal solid waste. The major environmental concerns associated with landfilling of wastes are related to the leachate generation and eventual discharge of leachate into the environment. Leachate quality is formed due to aerobic and anaerobic processes taking place in landfill. During aerobic decomposition of wastes, which is short in period, organic matters are converted to CO2, H2O and volatile acids. Anaerobic decompositon of wastes takes place in three phases, and methane, carbon dioxid, ammonia, and hydrogen sulfide gases are generated. In order to prevent leachate from percolation to ground water, natural or synthetic liners must be constructed at the bottom of landfill. Babol municipal landfill is located in Angelsi region, 30 km southwest of Babol with general slope of 14%. The total area of this site is 4 hectare. Yearly average municipal soild waste generation of Babol is 136 mertic tonne. So the life time of this site is estimated to be 4 years. Generation rate of primary leachate in this landfill is about 11.8m3 per day, for waste field capacity of 0.6 cm/cm and moisture content of 70%. Steress due to vehicle is negligible (0.001492 kg/cm3). Leachate management system in Bobal municipal landfill is composed of three elements: leachate trench with low permeability of K=10-3 cm/sec, comprised of sand with 16-32 mm in diametere and depth of 30cm. Thus 10500 m3 of sand is used to construct these trenches in 3.5 ha of use full area available for landfilling. Leachate collection system is made of cement pipes with 15 cm in dimeter. These pipes are especially prepared for this purpose. And finally a liner made of local clay compacted in thickness of one meter, so the maximum conductivity of this liner was in the order of mangitude of 10-7cm/sec.