Sustainable Utilization of Rice Husk Activated Charcoal as Wastewater Decontaminant

Activated charcoal is used in water, gold and gas purification, metal extraction, medicine, sewage
treatment, filters in compressed air, air filters in gas masks and respirators, and many other
applications. Due to its high demand, alternative means of production apart from non-renewable
sources, is time honoured. In view of these facts, activated charcoal was prepared from rice husk, an
agricultural waste, by pyrolysis and chemical activation. The optimum systematic preparation
conditions such as the effects of impregnation ratio, concentration, temperature and pyrolysis
temperature and time on the efficiency of the product were investigated. The chemically activated
charcoal was characterized by measuring porosity, bulk density, pore volume and size, surface area,
iodine number, percentage yield, ash and moisture contents. The adsorbent was further characterized
by Fourier-transform infrared spectroscopy and scanning electron microscopy. The performance of
activated charcoal prepared as adsorbent of pollutants in wastewater was tested using standard
analytical methods. Overall, the results revealed that there was a general significant (p<0.05)
decrease in the total hardness, alkanility, chemical oxygen demand, biological oxygen demand,
nitrate, total dissolved solid, total suspended solid, total solid, sulphate, nitrate, chloride, and heavy
metals in rice husk acivated charcoal treated filtrate when compared to the untreated. Although,
values of physicochemical parameters obtained in filtrate fromthe rice husk-based activated charcoal
were generally lower than that of the commercial (control), the differences were not statistically
significant (p>0.05). The results indicated that wastewater treated with the adsorbent were below the
recommendations of international standards for maximum limits of effluent to be discharged into
sewage, stream and drinking water. The study therefore recommends the use of rice husk-based
activated charcoal as an efficient and environmental friendly wastewater treament option.