Azoic dyes are known as toxic contaminants. Methyl orange is one of these dyes, is removed from wastewater principally through biological, chemical or physical processes. This article will describe the removal of the methyl orange from the water by adsorption onto activated carbon. This material is characterized before and after use in adsorption by various techniques. The methyl orange adsorption efficiency was studied varying contact time, the mass of activated carbon, pH, initial solution concentration, and temperature. The adsorption was found fast attainment equilibrium in 30 min with better performance for the sorbent and appears to be enhanced by low pH. Kinetic data for methyl orange was found to follow pseudo-second order model and the Langmuir model better describes the adsorption process. A maximum amount of methyl orange adsorbed was registered at 113.63 mg/g. The influence of temperature on adsorption and the thermodynamic study showed that free energy and the enthalpy exhibit negative and positive values, respectively, which shows that the methyl orange adsorption on the activated carbon is a spontaneous and endothermic process. The desorption/regeneration process was studied by using different percentages of ethanol and distilled water and it appears to be the best desorption to regenerate methyl orange. The use of 90% ethanol gave a rate of adsorbed methyl orange regeneration close to 89%. On other hand, these results indicate the significance of activated carbon as new support for the elimination of the methyl orange.

Leachate accumulation is a major concern for municipal solid waste (MSW) landfills as it causes potential harm to public health and poses a significant threat to surface water and local groundwater systems. This article presents the results of analyses on malodorous treatment at the solid waste landfill located in Casablanca, Morocco, using bio-deodorization as a pre-treatment technology. The main goal of this study is to remove odorous gases from landfill leachate. Microbial strains of Bacillus and Pseudomonas were seeded in a leachate pond to treat the odorous emissions from landfill leachate and consequently improve environmental quality and human health. After 28 days of seeding, the results showed that the addition of Bacillus and Pseudomonas greatly reduced the concentration of chemical oxygen demand (COD), biological oxygen demand (BOD5) and the ionic concentration of NH4+ to approximately 27.928 mg/L, 11550.3 mg/L and 1533 mg/L, respectively, with lower energy consumption, resulting in an average overall operational cost of 53.97 USD/m3. In addition, a significant reduction in total nitrogen (32.80%), nitrites (NO2–) (99.82%), nitrates (NO3–) (46.81%) and total phosphorus (49.50%) concentrations was also achieved at a post-treatment environmental pH of 8.5. These findings extend the field of application of biological deodorization and provide new insights into malodorous treatment methods.