Anaerobic digestion of ultrasonicated sludge at different solids concentrations - Computation of mass-energy balance and greenhouse gas emissions. (15th January 2016)

• Record Type: Journal Article
• Authors: Pilli, Sridhar; Yan, S.; Tyagi, R.D.; Surampalli, R.Y.
• Is Part Of: Journal of environmental management. Volume 166(2016)
• Page Start: 374
• Page End: 386
• Publication Date: 2016-01-15
• Subjects: Pre-treatment -- Biodegradability anaerobic digestion -- Mass-energy balance and greenhouse gas emissions; Environmental policy -- Periodicals; Environmental management -- Periodicals; Environment -- Periodicals; Ecology -- Periodicals; 363.705
• DOI: 10.1016/j.jenvman.2015.10.041
• Languages: English
• ISSNs: 0301-4797

Abstract

Abstract: Two cases of anaerobic digestion (AD) of sludge, namely (i) with pre-treatment and (ii) without pre-treatment, were assessed using mass-energy balance and the corresponding greenhouse gas (GHG) emissions. For a digestion period of 30 days, volatile solids degradation of the control sludge and the ultrasonicated secondary sludge was 51.4% and 60.1%, respectively. Mass balance revealed that the quantity of digestate required for dewatering, transport and land application was the lowest (20.2 × 10 6 g dry sludge/day) for ultrasonicated secondary sludge at 31.4 g TS/L. Furthermore, for ultrasonicated secondary sludge at 31.4 g TS/L, the maximum net energy (energy output − energy input) of total dry solids (TDS) was 7.89 × 10 −6 kWh/g and the energy ratio (output/input) was 1.0. GHG emissions were also reduced with an increase in the sludge solids concentration (i.e., 40.0 g TS/L < 30.0 g TS/L < 20.0 g TS/L). Ultrasonication pre-treatment proved to be efficient and beneficial for enhancing anaerobic digestion efficiency of the secondary sludge when compared to the primary and mixed sludge. Highlights: Energy sustainability of the pre-treatment and anaerobic digestion is evaluated. Energy and GHG emissions are considered as criteria in evaluating the process. Ultrasonication pre-treatment of sludge followed by AD is energetically sustainable. GHG emissions are reduced with pre-treatment of sludge followed by AD.