Performance evaluation of a granular activated carbon-sequencing batch biofilm reactor pilot plant system used in treating real wastewater from recycled paper industry

Abstract

A pilot scale granular activated carbon-sequencing batch biofilm reactor with a capacity of 2.2 m3 was operated for over three months to evaluate its performance treating real recycled paper industry wastewater under different operational conditions. In this study, dissolved air floatation (DAF) and clarifier effluents were used as influent sources of the pilot plant. During the course of the study, the reactor was able to biodegrade the contaminants in the incoming recycled paper mill wastewater in terms of chemical oxygen demand (COD), adsorbable organic halides (AOX; specifically 2,4-dichlorophenol (2,4-DCP)) and ammoniacal nitrogen (NH3-N) removal efficiencies at varying hydraulic retention times (HRTs) of 1-3 days, aeration rates (ARs) of 2.1-3.4 m3/min and influent feed concentration of 40-950 mg COD/l. Percentages of COD, 2,4-DCP and NH3-N removals increased with increasing HRT, resulting in more than 90% COD, 2,4-DCP and NH3-N removals at HRT values above two days. Degradation of COD, 2,4-DCP and NH3-N were seriously affected by variation of ARs, which resulted in significant decrease of COD, 2,4-DCP and NH3-N removals by decreasing ARs from 3.4 m3/min to 2.1 m3/min, varying in the ranges of 24-80%, 6-96% and 5-42%, respectively. In comparison to the clarifier effluent, the treatment performance of DAF effluent, containing high COD concentration, resulted in a higher COD removal of 82%. The use of diluted DAF effluent did not improve significantly the COD removal. Higher NH3-N removal efficiency of almost 100% was observed during operation after maintenance shutdown compared to normal operation, even at the same HRT of one day due to the higher dissolved oxygen concentrations (1-7 mg/l), while no significant difference in COD removal efficiency was observed.

A systematic literature review of biocarriers: Central elements for biofilm formation, organic and nutrients removal in sequencing batch biofilm reactor

“…High suspended solid and color removal efficiencies were obtained using GAC with physical adsorption as the main colour removal mechanism [53,60]. Other researchers also claim that, after treatment with the pilot GAC-SBBRR, it was almost hard to foresee 2,4-dichlorophenol (2,4-DCP) residues in the effluent [55,56]. Results of the study by [58] was in the agreement with several other studies showing high COD removal efficiency.…”

“…12a and 12b) results in high biomass holding, allowing the process to significantly operate at higher liquid throughputs and OLR [55]. This is because of the numerous advantages possessed by GAC that result in high process stability and increased substrate removal efficiency: high surface area, porosity, large adsorption capacity, rough medium and continuous GAC bio-regeneration [56,57]. Since GAC's low specific gravity enables fluidization even at less upflow velocity, its capacity for sorption shields the attached biofilm from shock loads [58,59].…”

“…Researchers [55,56], reported that, after treatment with the pilot GAC-SBBRR, it was almost hard to foresee 2,4-dichlorophenol (2,4-DCP) residues in the effluent. A study [54] using same biocarrier material treating pentachlorophenol (PCP) also reported good performance efficiency and stable treatment process under stern organic load fluctuations with about 61% PCP removal.…”

“…Virgin GAC, with a dimension of 1.3 x 0.3 mm of porous structure, shown in Fig. 26 (a) and (b) offer niches of shelter from the accompanying shear forces and maintain surface biofilm [56]. It also contributed to the growth of microorganism and improved the GAC-SBBR's ability to extract COD and Adsorbable Organic…”