Removal of textile dyes from wastewater have recently attracted much attention, due to the toxicity, difficult visibility, and thereby the negative consequences on the aqueous environment. Therefore, there have been diverse promising new techniques such as adsorption for dyes removal from industrial wastewater. Compared to the highly cost treatment techniques, removal of dyes using the adsorption process is relatively simple and requires less cost. Synthetic zeolite was used in this research as a high capacity nano-adsorbent for the removal of reactive dyes from coloured wastewater. The impact of main parameters: dose of adsorbent (0.0025 to 0.02 g), pollutant concentration (25 to 200 mg/L), contact time (10 to 120 minutes), degree of agitation (25 and 300 rpm), and solution pH (2 to 8) on adsorption performance of the synthesised zeolite was investigated. The optimum values of these parameters to remove dyes efficiently at 90 % removal were 0.02 g, 200 mg/L, 80 min, 300 rpm, and 6-7 respectively. Also, two models were evaluated, the Langmuir and Freundlich isotherms. Langmuir isotherm was more efficient for representing the data than the Freundlich. The results of the Langmuir isotherm gave KL = 0.08 L/mg, qm = 6.02 mg/g, and R 2 = 0.98, which fitted to the adsorption data of zeolite. Reactive dye adsorption by synthetic zeolite is a vital tool in identifying the fate of dye removal from industrial wastewater treatment plants.

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In this research, the ability of calcareous soil to absorb ammonium was investigated and the effect of compost amendment as a natural organic source on ammonium adsorption was also studied. The pH, dissolved ammonium concentrations, ammonium adsorption capacity, and cation exchangeable capacity for the soil samples were analyzed in relation to an untreated control and treatment with compost under ambient temperature and different initial ammonium concentrations (10, 20, 30, 40, 50, 70, and 100 mg/L). The amounts of ammonium adsorbed increased along with initial concentrations of dissolved ammonium for control and treatment with compost. The models evaluated in this study included the Langmuir and Freundlich isotherms. Ammonium adsorption was found to conform to the Freundlich equation isotherm more than that with Langmuir. The highest adsorption capacity was exhibited by 100 mg/L added initial ammonium concentration. Adding compost as a source of organic matter enhanced the adsorption capacity of calcareous soil with an increase in the adsorption of 36%, which indicated that the organic matter is a key limiting parameter in the mechanism of ammonium adsorption. Ammonium adsorption by calcareous soils is an important process in identifying the ammonium nitrogen route in soil-water systems.

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