Site selection: The study area is situated at the northwestern part of Bangladesh, namely, Rajarampur locality of Nawabganj Sadar thana of Chapai Nawabganj District. Materials: The chemicals used in this investigation were of high purity analytical grade. Distilled deionized water (DDW), obtained through the deionization plant (TYP-2500, Deng Yuan, China), was used throughout. Perkin Elmer pure atomic spectroscopy standard solution (Perkin Elmer, USA) of arsenic (CAS # 7440-38-2) was used for calibration of arsenic. A number of standard solutions, reducing solutions, buffer solutions, ternary acid mixture and other solutions were prepared according to respective standard procedures (APHA 1995; Hesse 1994; Shimadzu). The other reagents were from Merck (Germany), Fluka (Switzerland) and Sigma Aldrich (USA). TCLP tests: First preliminary TCLP evaluations were performed with a minimum 100g of semi-solid waste for: (1) Determination of percent solids, (2) Determination of whether the solid portion of the waste requires particle size reduction or not and (3) Determination of which of the extraction fluids are to be used for the TCLP test. Leaching tests under Simulated Natural Column (SNC): The natural disposal conditions considered in the study include on land disposal in typical non-hazardous landfill dump or backyard and dumping in household ditch. Microbially active, mildly alkaline, anaerobic conditions characterize mature landfill (Christensen et al 2001). In the experimental section a PVC column, 30 inch in length and 6.3 inch in diameter, was operated in down flow mode. A syringe delivered 0.35 mL/min of influent, maintaining the water level at a total saturated bed volume of about 13 L. The column was operated at room temperature of 30ºC. 5 cm thick pea gravel layers (0.4-1.0 cm diameter) were provided above and below of the active bed ensuring even flow distribution. Characterization of sludge, materials of SNC and feed water: The arsenic waste/sludge of SONO filters were characterized by measuring solid content, pH, redox potential, concentrations of arsenic and iron. The materials of SNC and feed water were characterized by measuring pH, redox potential, electrical conductivity, dissolved oxygen, total dissolved solids, concentrations of arsenic, iron, calcium and magnesium, total coliform and fecal coliform. All the parameters were measured using standard procedures and properly calibrated instruments. Extraction and analysis for metal concentrations: Prior to analysis of water samples for total arsenic (AsT) and total iron (FeT) the aqueous samples were subjected to mild digestion with HNO3 (APHA 1995). But the water samples were not pretreated for estimation of calcium and magnesium. For estimation of AsT, FeT, Ca and Mg in soil samples, these were digested with H2SO4-HClO4 acid mixtures (Sakamoto et al 2001; Hesse 1994; Shimadzu).Microbiological examination: Membrane filter (MF) method was used to count total and fecal coliform bacteria. A volume of 100 ml water was filtered through gridded nontoxic Nitrocellulose membrane filter (Millipore, USA), 47 mm in diameter having pore size of 0.45 µm, under manual vacuum condition. Statistical analyses: The datasets were treated separately for analyzing basic statistical parameters and making cross tabulations and cross plots. The statistical software used in the data analyses includes SPSS (release 13.0) statistical software package (SPSS Inc., Chicago, Illinois, 2004), STATGRAPHICS Centurion XV (release 12.2.14) software (StatPoint Technologies, Inc., Warrenton, Virginia, 2007). Mathematical models were established based upon simple and multiple regression analysis using SPSS, STATGRAPHICS Centurion XV and CurveExpert (release 1.34) and Microsoft Excel (release 12.0.4518.1014, 2006). The models were cross-checked by analyzing ANOVA, P value, r value (Pearson correlation coefficient) and Durbin–Watson statistics.