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: Leachate, a highly contaminated liquid, is produced by separating wastes and introducing moisture into the waste layers. Biological toxicity evaluation is a method that may be used to analyze the toxicity of leachate to organisms and plants. Sorghum bicolor was employed in this study to evaluate the acute toxicity of raw leachate and landfill leachate. Methods: Leachate was collected from different locations within the refuse that was collected and mixed in a sampling container. The physiochemical characteristics of the leachate were analyzed in both raw leachate and landfill leachate. Germination rate, root weight, and root length were measured 24, 48, and 72 hours after planting for leachate dilutions of 25%, 50%, 75%, and 100%, respectively. Results: Raw leachate had greater concentrations of metals (Fe, Zn, Cu, Mn, Cr, Cd, and Pb), chemical oxygen demand (COD), total dissolved solids (TDS), total suspended solids (TSS), nitrate, ammonia, and phosphate, as well as a more acidic pH (< 6), as compared to landfill leachate. The results showed that landfill leachate had a lower potential for toxicity than raw leachate, with seed-germination rates of 0.1 and 0 in the presence of 75% landfill leachate after 48 and 72 hours, respectively, as opposed to 0.3 and 0.1 in the presence of raw leachate. Conclusion: The findings show that raw leachate can include higher concentrations of metals and organic compounds, which can be one of the causes of Sorghum seed phytotoxicity. Waste leachate management is one of the most important pillars of environmental protection, and it should be taken into consideration by the right authorities.

Landfill leachates are potential threats for environmental degradation. This study was conducted to determine the leachate quality, to identify the dominant pollutants and to evaluate the leachate pollution potential of an active and closed dumping ground of an uncontrolled municipal solid waste (MSW) landfill site in Kolkata, India using leachate pollution index. The results of the physico-chemical and biological analyses of leachate indicated that landfill site was in its methanogenic phase. Among the analysed leachate pollutants, TDS, BOD5, COD, TKN, NH3-N, Cl¯, TCB, Pb, and Hg surpassed the leachate discharge standards for inland surface water as specified by the municipal solid waste (management and handling) rules, 2013 for both the dumping grounds. Moreover the concentrations of total Cr and Zn also exceeded the leachate disposal standards for the active dumping ground. The leachate pollution potentialities of both the active and closed dumping grounds were comparable as the overall LPI obtained 34.02 and 31.80 respectively. The overall LPI, LPI organic (LPIor), LPI inorganic (LPIin) and LPI heavy metals (LPIhm) of both the dumping grounds largely exceeded the LPI and sub-LPI values for treated leachate before disposal to the inland surface water. In terms of the individual pollution rating, total coliform bacteria, TKN, NH3-N and Hg were identified as the dominant pollutants and major contributing factors for the leachate pollution potential.

Leachate of urban solid waste landfills is one of the most important of environmental concerns. Today, electrocoagulation is considered as a method for leachate treatment. In this process coagulants are produced during metallic electrode dissolution. In this article, treatability of old leachate of Kahrizak landfill of Tehran by electro-coagulation method was studied. The study was done in laboratory scale by using steel electrodes grades ST-12, ST-37, and CK-45 and measuring COD, SS and ORP parameters. COD removal was obtained 42.66, 34.37 and 35.2 percent for ST-12, ST-37 and CK-45 electrodes while the operation time and current were 100 min and 7.2 A for initial COD concentration of 160, 000 mg/l. COD removal increased 6.78, 4.38 and 12.12 percent when the operation time increased to 140 min, respectively. As well, COD removal was increased 38.98, 22.64 and 25.38 percent and SS removal was enhanced 16.4, 19.79 and 18.71 percent for ST-12, ST-37 and CK-45 electrodes, while the current density increased from 33.33 to 66.166 A/m2. The results also showed ST-12 electrode had the best efficiency for leachate treatment with COD and SS removal of 64.67% and 98.79% respectively while the current density was 66.166 A/m2 equals charge's loading of 46.155 F/m3.

Organic and mineral compounds generated as products of waste mineralization within biological processes and accompanying physical and chemical processes are washed out by percolating rainwater through the deposit of wastes in landfill and form leachate that has created many health and environmental concerns. This study intended to determine the efficiency of reducing COD, BOD5, TS and color of Hamadan landfill leachate by using carbon nanotubes. Experiments were performed in batch reactor and changing effective factors such as pH, time and concentration of iron nanoparticles. The efficiency of carbon nanotubes were investigated using a statistical test, One-Way ANOVA software SPSS-12. Highest removal efficiency was at concentrations of 2500 mg/ L NZVI, pH=2.5 and 10 minutes reaction time, 58.23%, 12.5%, 66.87%, 80% for COD, BOD, TS and color, respectively. The project results showed high potential for carbon nanotubes into absorbing organic use for treatment or pretreatment of Hamadan landfill leachate.

Tehran has a population of over 12 million and produces more than 7500 tons of waste every day. Tehran's municipal solid waste is processed and landfilled at Kahrizak disposal center. Due to inappropriate waste management, a lake with a leachate volume of 180, 000m3 has been formed. To solve this problem a leachate treatment plant is currently under construction. A byproduct of leachate treatment is biogas. In this study, the feasibility of electricity generation using biogas has been investigated. Considering that 68.81% of the waste is degradable, the produced leachate has a high organic load (COD=53900 mg/L and BOD=34400mg/L). The results showed that a power plant with a capacity of 1.8 MW could be constructed in the site. This electricity can be utilized in Kahrizak Disposal Site and also sold to the network (10 US cents/ kilowatt). Financial analysis using ProForm software shows 1.3 years of payback period and emission reduction of carbon dioxide equal to 5752 tones/year in comparison with the natural gas power plant. Therefore this project is financially feasible for private investors with internal rate of return equal to 77% or more.

Background and Objectives: Wet air oxidation (WAO) is One of the advanced oxidation process which reduce organic matter concentration from industrial wastewater, toxic and non biodegradable substances and, solid waste leachate, etc. In this study the efficiency of wet air oxidation method in leachate treatment generating from Esfahan Composting factory was Evaluated.Material and Methods: The experiment was carried out by adding 1.5 Lit of pretreated leachate sample the steel reactorwith the volume of 3L. The reactor then underwent10 bar pressure at different temperature (100, 200 and 300oC) and various retention time (30, 60 and 90 min). Leachate sample in 18 stages from composting factory in Isfahan in the volume of 20 Lit was taken and the WAO method, was used for pre-treatments. Removal efficiency of COD, BOD, NH4-N, NO3 and TSS were examined.Results: The results showed that the removal efficiency was more than 35% for COD, 38% for BOD, and 85% for TSS within one hour of reaction. The Maximum removal efficiency obtained in this study were 53.3% for NH4-N and 73.9 % for NO3-N.Conclusion: the results indicate that the reaction temperatures are the most important factors affecting degradation of organic matter. COD and BOD5 removal efficiency by WAO process increased as the time of reaction went up. In addition, BOD5/COD ratios of the effluents, which are generally regarded as an important index of biodegradability of leachate sample, were determined and improved grately as it reached to 84%. TheWAO process presented in this paper is considered an efficient process for pretreatment of leachate, as the COD, BOD5 and NO3 reduction observed in leachate samples.

The dumping of solid waste in uncontrolled landfills can cause significant impacts on the environment and human health. The principal concern is focused on the pollution potential due to migration of the leachate generated from the landfill sites into the groundwater, the surface water or the sea. In this study, used of a technique that has been developed to quantify the landfill leachate pollution using an index known as Leachate Pollution Index (LPI). Also, monitoring of leachate quality was carried out at three dump sites as Talesh, Roudsar, and Ferydounkenar from cities of northern Iran. The leachates were monitored for changes in pH, TDS, COD, BOD, TKN, Ammonia-Nitrogen, and heavy metals. Leachate Pollution Index (LPI) for Talesh, Roudsar, and Frydunkenar leachate was 23.64, 27.51, and 17.96, respectively. These results showed that Roudsar leachate is more polluted than Talesh, and Frydunkenar leachate. Further, leachates of three dump sites showed that higher LPI value those than of 7.4 obtained for the treated leachate that can be disposed into inland surface water  are more.

Landfill leachate presents hardly treatable, highly complex and very toxic environmental effluent originated in the municipal solid waste degradation process. Although, numerous treatment methods were developed so far, none of them alone could achieve permissible limits of the primary pollutants to discharge into natural recipients. The current study aimed to develop and apply the process to treat landfill leachate by simultaneous application of electrochemical methods, ultrasound, electromagnetic field and ozonation to achieve the legal criteria for its discharge into natural recipient and minimize its adverse environmental impacts. For this purpose, old landfill leachate was taken from the Piskornica (Koprivnica, Croatia) sanitary landfill. Prior to the treatment, the leachate was supplemented with NaCl (2 g/L) and subjected to simultaneous treatment with stainless steel electrode plates, ultrasound and recirculation through electromagnetic field. After 45 minutes, stainless steel electrode plates were replaced by iron electrodes and treated for another 10 minutes followed by 15 minutes of the treatment with aluminum electrode plates. Ultrasound and recirculation through electromagnetic field were also applied during Fe and Al electrode treatment. Finally, the electrodes were removed and the suspension was mixed with ozone for another 30 minutes and allowed to settle for an hour. Following the combined treatment, the removal efficiency for the turbidity, color, suspended solids, ammonium, phosphates and heavy metals was 99% or higher, while the removal of COD was 97%. All the measured parameters in the treated leachate were lower compared to upper permissible limit for discharge into natural recipient.