Dye Wastewater Treatment Using Wheat Straw Biochar in Gadoon Industrial Areas of Swabi, Pakistan

With growing industrialization, the dye industries release a huge quantity of dye-contaminated water to the surrounding environment which affects the agricultural land and crop productivity. The present study was carried out to apply the wheat straw-pyrolyzed biochar to the dye industry wastewater to reduce the chemical oxygen demand (COD) and other toxic metals. For the application of biochar, wastewater samples were collected and analyzed for various parameters, namely, pH, temperature, total dissolved solids, electrical conductivity, sulfate, sodium, nitrate, calcium, potassium, chloride, and chemical oxygen demand. All the results were below the National Environmental Quality Standards of Pakistan (Pak-NEQs 1997/2008) and US-EPA except COD (i.e., 236 mg/L). For the reduction of COD, the wastewater samples were treated with wheat straw biochar through a group of experiments under variable adsorbent dosage and contact time. The biochar application, i.e., 0.5, 1.0, 1.5, 2.0, and 2.5 in g/L, removed the COD up to 19.5, 34, 44.5, 56, and 62% with a significance of p < 0.05. The results stated that COD was reduced ~ 62% (up to 90 mg/L) with 2.5 g of adsorbent for 2-h contact time, and found below the permissible limit of Pak-NEQs (1997/2008); that is, 150 mg/L was considered as an optimum dose. Findings from the present study suggested that biochar derived from agro-waste could be a promising option to reduce the COD and other element concentrations from dye industry wastewater and improve the water quality. Reducing COD and other water quality parameters through biochar will surely limit the hazardous impacts of wastewater on the surrounding environment.