Wastewater treatment in the pulp-and-paper industry: A review of treatment processes and the associated greenhouse gas emission

Wastewater Treatment and Reclamation: A Review of Pulp and Paper Industry Practices and Opportunities

“…GHG emissions by on-site and off-site processes in a typical industrial wastewater treatment plant that used aerobic, anaerobic, and hybrid anaerobic/aerobic treatment processes were studied by Bani Shahabadi et al (2009Shahabadi et al ( , 2010 and Yerushalmi et al (2011). Yerushalmi et al (2013) and Ashrafi et al (2013Ashrafi et al ( , 2014Ashrafi et al ( , 2015 estimated GHG emission and energy consumption by wastewater treatment plants of the P&P industry and determined the contribution of individual processes to the on-site and off-site GHG emissions. On-site GHG emissions are due to liquid and solid treatment processes as well as biogas and fossil fuel combustion for energy generation.…”

“…One way to reduce sludge is to place increased emphasis on anaerobic biological treatment as an early step in the treatment program (Ashrafi et al 2015;Kamali and Khodaparast 2015;Ordóñez et al 2010). Alternatively, researchers have shown that thermophilic (higher temperature) biological treatment systems can achieve better efficiency and lower sludge amounts even under aerated conditions (LaPara and Alleman 1999; Skouteris et al 2012).…”

“…Ashrafi et al (2015) emphasized impacts of different wastewater-treatment options on greenhouse gas (GHG) emissions. In addition to the evolution of CO2, methane, and other GHG components from the waste materials, one also needs to be concerned about GHGs associated with the usage of electrical energy during the treatment of wastewater (Baig and Liechti 2001;Ashrafi et al 2015). For instance, though improved efficiencies and treatment rates often can be achieved with modern reactors designed for biological wastewater treatment, such results from BOD and COD tests will be different if the wastewater sample contains difficult-to-biodegrade oxidizable compounds or toxic materials that inhibit biological activities.…”

“…Also there have been review articles devoted to the treatment of P&P mill effluents using anaerobic conditions (Graves and Joyce 1994;Rintala and Puhakka 1994;Savant et al 2006;Meyer and Edwards 2014;Kamali and Khodaparast 2015). Many other authors have reported evaluations of factors affecting the anaerobic treatment of P&P mill wastewaters (Sierraalvarez et al 1991;Korczak et al 1991;Vidal et al 1997;Kortekaas et al 1998;Bengtsson et al 2008a;Ruas et al 2012;Krishna et al 2014;Larsson et al 2015).A plus side of anaerobic treatment is that one does not need to pay for the pumping of air into the system (Maat and Habets 1987), and, according to many reports, the amounts of sludge produced are generally less than in conventional aerated biological treatment systems (Ashrafi et al 2015;Kamali and Khodaparast 2015). Anaerobic processes produce gases such as methane, requiring their collection and safe disposal.…”

“…In such systems the wastewater to be treated is introduced below a layer of sludge and allowed to percolate up through that layer (Maat and Habets 1987;Hynninen 1998). The flow velocity can be as high as 2 to 3 m/h in some high velocity upflow systems (Rajeshwari et al 2000).Under anaerobic conditions, where the production of sludge is expected to be less (Ashrafi et al 2015;Kamali and Khodaparast 2015), the same approach nevertheless has been evaluated (Lettinga et al 1980;Habets and Knelissen 1985;Maat and Habets 1987;Rajeshwari et al 2000;Buzzini and Pires 2002;Roest et al 2005;Bhunia and Ghangrekar 2008;Buyukkamaci and Koken 2010;Sheldon et al 2012). For instance, Bhunia and Ghangrekar (2008) found that such a system could be optimized by controlling the organic loading rate (OLR) to the system and by inoculating the system with thick sludge.…”