The Comparative Study between the Adsorptive Capacity of Activated Carbon Obtained from the Enhanced Hydrothermal Polymerization Process with Conventional Activated Carbons in the Removal of Micropollutants of Concern

Kasonde, Vimbai

The Comparative Study between the Adsorptive Capacity of Activated Carbon Obtained from the Enhanced Hydrothermal Polymerization Process with Conventional Activated Carbons in the Removal of Micropollutants of Concern

Thesis / Dissertation

2023

Abstract

Adsorption is one of the most widely used techniques employed for the tertiary treatment of wastewater to remove micropollutants. One of the most popular adsorbents used towards adsorption is activated carbon. However, due to the high cost of the conventional commercial activated carbon (produced from coal, which is a finite resource), it is important to find alternative precursors that are readily available, low cost, and can potentially produce activated carbon which is effective in the adsorption process. Sludge from wastewater treatment plants is one alternative which has been investigated and found desirable due to its high organic content. It is an unavoidable by-product of water treatment facilities that is becoming difficult to manage due to stricter disposal laws. The use of sludge as a precursor for activated carbon production serves to address the issue of an alternative, relatively low-cost adsorbent and the sludge disposal dilemma. Hence the sludge, which is an otherwise waste product is converted into a useful resource to aid in the reduction of the pollution of water which is a scarce commodity. In this study, hydrochar derived from primary sludge combined with waste activated sludge was used to produce activated carbon through pyrolysis. The hydrochar derived activated carbon (HC-AC) was characterized along with a commercial granular activated carbon (GAC) and a green alien wood activated carbon (AW-AC). The three carbons were later used in batch adsorption tests to determine the optimum conditions needed for each carbon to achieve maximum removal of methylene blue dye and lead (II) ions in aqueous solution by varying parameters such as pH, adsorbent dosage, initial concentration of the adsorbate, and contact time. Results from these tests were compared at the optimum conditions for each adsorbent and it was found that for methylene blue dye adsorption the percentage removal was in the order HCAC (99.28%) > GAC (99.13%) > AW-AC (98.73%). The percentage removal of lead (II) ions was in the order HC-AC (99.33%) > GAC (97.25%) > AW-AC (96.92%), showing that at optimum conditions, HC-AC performed slightly better than the other adsorbents in the removal of the pollutants

Keywords

Engineering

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