Application of Aerobic Granular Sludge (AGS) Technology for the Treatment of Pulp Mill Effluent

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The pulp and paper industry produces a significant amount of wastewater with toxic and recalcitrant compounds. Pulp and paper wastewater (PPW) requires a special treatment method that is diverse enough to deal with the complexities of this type of wastewater. The present study was aimed primarily at the removal of tannin/lignin from PPW using aerobic granular sludge (AGS) technology. Aerobic granules were cultivated in a sequencing batch reactor (SBR) with tannin/lignin present in the range of 50-200 mg/L. Granules were cultivated within 9 days of operation of the sequencing batch reactor (SBR), with SVI30 of 51.6 mL/g, achieving steady-state within the first three weeks of operation. On average, the COD removal efficiency for synthetic PPW was 90%. Tannin/lignin were removed up to 80% during the initial stages, but slowly decreased to an average removal of 70%. The mature granules were then transferred to a real PPW wastewater system containing tannin/lignin concentration up to 500 mg/L. Biodegradation and biosorption were observed to be the two pathways for the removal tannin/lignin. Biosorption was a primary form of removal at lower concentrations, achieving 74% removal at 50 mg/L. The biosorption ability reduced to 58% removal at 200 mg/L. This reveals that biodegradation prevails at these higher concentrations. The Haldane kinetic parameters were: Vmax = 0.93 (g tannin/lignin/g VSS· day), Ks = 1910 mg/L, and Ki = 27 mg/L. Various adsorption kinetic models and isotherms were fitted to the system. The Langmuir isotherm coefficients were: (x/m) max = 21.5 (mg tannin/lignin/g SS), b = 0.00386 L/mg. The Freundlich isotherm had coefficients of n = 1.172, K = 0.1174. COD removal of 79% and a tannin/lignin removal of 56% were achieved with real PPW. Furthermore, experimental runs in warmer and more humid temperature conditions revealed higher removal efficiencies, achieving about 80% tannin/lignin degradation at a concentration of 130 mg/L. The most prominent species responsible for the degradation of these toxic substances were Pseudomonas, Corynebacteriaceae and Flavobacterium.
Vashi, H. (2019). Application of Aerobic Granular Sludge (AGS) Technology for the Treatment of Pulp Mill Effluent (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from