Treatment of Organic and Inorganic Pollutants in Municipal Wastewater by Agricultural By-product Based Granular Activated Carbons

The objective of this investigation was to evaluate pecan and almond shell-based granular activated carbon’s viability to effectively remove organic and inorganic pollutants in municipal wastewater compared to commercial carbons, Filtrasorb 200 (bituminous coal-based), and GRC-20, 206C AW (coconut shell-based). The solution to the objective was approached under three distinct phases, namely (I) physical and chemical characterization of the pecan and almond shell-based experimental and bituminous coal and coconut shell-based commercial granular activated carbons; (II) treatment of organic contaminants in municipal wastewater by experimental and commercial GACs; (III) treatment of inorganic contaminants in municipal wastewater by experimental and commercial GACs. Phase I study showed that the almond shell-based chemically activated carbon (ALA) had the largest total surface area (1340 m/g) including the commercial carbons. The bulk densities of both physically and chemically (0.49 to 0.57 g/m) -activated pecan shell-based carbons were comparable to those of commercial carbons (0.49 to 0.54 g/m). ALA had the highest attrition (31.68%) compared to chemically activated pecan shellbased carbon (PSA) with lowest attrition (7.10%). PSA also contained the lowest ash, a desirable attribute. Activation affected conductivity. Chemical activation lowered conductivity when compared to physical activation. Multivariate analysis showed that steamand acid-activated pecan shell-based carbons (PSS and PSA) had more similarity to commercial carbons. Phase II study showed that PSS had higher adsorptive capacity towards Chemical Oxygen Demand (COD) than carbon dioxide-activated pecan shell-based carbon (PSC)