Problem statement: Yemen one of the developing country suffering from water pollution. Landfill is one of the source of water pollution. There are several boreholes located close to Ibb landfill used for drinking water. A study of composition of landfill leachate and groundwater pollution was conducted at Ibb landfill, which is located at Al-Sahool area, north of Ibb City, Yemen. Approach: The leachate was sampled at three different locations of the landfill, at the landfill itself and 15 and 20 m downstream of this landfill. Groundwater samples collected from 5 boreholes to study possible impact of leachate percolation into groundwater. Leachate and groundwater samples were collected during dry season only, due to the excessive generation of leachate during this season. Objective of this study was significant to assess degree of groundwater pollution due to Ibb landfill leachate at Al-Sahool area. The leachate and groundwater were physically and chemically characterized by using spectrophotometer HACH, BOD Trak HACH, flame photometer (PFP 7) and Inductively Coupled Plasma of Optical Emission Spectrometry (ICP-OES) model Vista MPX. Parameters measured were pH, temperature, Electrical Conductivity (EC), Total Dissolved Solids (TDS), Dissolved Oxygen (DO), Fluoride (F), Chloride (Cl), Sulphate (SO₄), Nitrites (NO₂), Nitrates (NO₃), ammonia-N (NH3-N), heavy metals (Pb, Zn, Ni, Cr, Cd, Cu), major cations (Na, Mg, Ca, K, Fe) and biological parameters (COD, BOD₅ and coliform group bacteria). Results: The results showed that, leachate at landfill most likely in methanogenic phase, based on the alkaline pH value recorded (pH = 8.46). The results also showed that 4 out of 5 boreholes were contaminated, where concentration of physico-chemical parameters are above the standard acceptable levels which required for drinking water adapted by Yemen's ministry of water and environment and by word standard. Conclusion: Therefore, landfill is dangerous for environment so government should do sanitary landfill to prevent further contamination to surface water, groundwater as well as soil

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The distribution coefficient, Kd, is often used to quantify heavy metal mobility in soils. Batch sorption or column infiltration tests may be used to measure Kd. The latter are closer to natural soil conditions, but are difficult to conduct in clays. This difficulty can be overcome by using a laboratory centrifuge. An acceleration of 2600 gravities was applied to columns of London Clay, an Eocene clay sub-stratum, and Cu, Ni, and Zn mobility was measured in centrifuge infiltration tests, both as single elements and in dual competition. Single-element Kd values were also obtained from batch sorption tests, and the results from the two techniques were compared. It was found that Kd values obtained by batch tests vary considerably depending on the metal concentration, while infiltration tests provided a single Kd value for each metal. This was typically in the lower end of the range of the batch test Kd values. For both tests, the order of mobility was Ni>Zn>Cu. Metals became more mobile in competition than when in single-element systems: Ni Kd decreased 3.3 times and Zn Kd 3.4 times when they competed with Cu, while Cu decreased only 1.2 times when in competition with either Ni or Zn. Our study showed that competitive sorption between metals increases the mobility of those metals less strongly bound more than it increases the mobility of more strongly bound metals.

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The groundwater quality in and around two landfills sites in the state of Selangor, Malaysia is studied to evaluate levels of contamination around an unengineered site and an engineered site. The two landfill sites are Ampar Tenang and Bukit Tagar. Data were obtained through site sampling from available boreholes. In addition results from published data and reports of previous works are used for analysis. The data indicate serious groundwater contamination in and around unengineered landfill sites. Analytical data include quality of groundwater, leachate and surface water in which many parameters were above the regulatory limits. Whereas, at the engineered site, contamination was generally below the standards. The findings serve to warn waste management industry stakeholders in Malaysia that for sustainability, unengineered landfills must be closed and cleaned up.