Hydrothermal Carbonization of Biosolids from Waste Water Treatment Plant

Abstract

The high moisture content of biosolid from a wastewater treatment plant limits its use for agriculture and energy applications. This limitation could be obviated by hydrothermal carbonization, which requires less energy compared to other thermochemical treatment processes, and results in stabilized solid hydrochar product. The present study examined this option by hydrothermally treating the biosolid at three temperatures (180, 200 and 220 °C) for 30 min, and at 200 °C for 15, 30 and 60 min. An increase of 50% in the heating value of the biosolid was obtained after this carbonization. A reduction in the nitrogen concentration in hydrochar was noted with an increase in phosphorus concentration, but potassium concentration remained largely unchanged. Additionally, the carbon to nitrogen ratio in the hydrochar product was higher than the biosolid that makes it suitable for agriculture applications. The chemical oxygen demand of the process water was in the range of 83,000 to 96,000 mg/L. The study thus provides insight into high-value products that can be generated by the hydrothermal carbonization of biosolids.

Hydrochar derived from municipal sludge through hydrothermal processing: A critical review on its formation, characterization, and valorization

“…b Yield (%) = (mass of each product/mass of feedstock) × 100, dry basis. -131 --a db = dry basis; TS = total solids of sludge feedstock; VM = volatile matter; FC = fixed carbon; HHV = higher heating value; references (Acelas et al, 2014;Afif et al, 2011;Ahn et al, 2020;Alatalo et al, 2013;Ali Shah et al, 2021;Amrullah and Matsumura, 2018;Anastasakis et al, 2018;Aragón-Briceño et al, 2017Becker et al, 2019;Berge et al, 2011;Bhatt et al, 2018;Biller et al, 2018;Breulmann et al, 2017;Brookman et al, 2018;Catallo and Comeaux, 2008;Chang et al, 2021;D. Chen et al, 2020;Chen et al, 2019Chen et al, , 2013bChen et al, , 2013aChu et al, 2020;Conti et al, 2020;Couto et al, 2018;  Results showed that WHSV between 1.5 and 3.1 hr -1 had no noticeable effect on co-HTG;  Co-HTG of MS with corn starch had slightly more H 2 and less CH 4 in gas composition than HTG of corn starch only;  Co-HTG resulted in less TOC yield than HTG of corn starch only.…”

Physico-chemical properties of hydrochars produced from raw olive pomace using olive mill wastewater as moisture source

“…This property is common to industrial organic wastes of interest such as agrifood, paper, and woodcrafts. Therefore, a drying step is required [8].…”

Sewage Sludge Thermal Treatment Technologies with a Focus on Phosphorus Recovery: A Review

“…Since the HTC process proceeds in a closed system, the phase change of the moisture does not occur so consequently the latent heat of vaporisation is not utilized in the process [88]. It requires less energy compared to other thermochemical treatment processes, and results in a stable solid product [89]. The hydrothermal process is characterized by high liquid yields, as its content is very high at the start of the process and almost does not change.…”