Effect of moisture on pretreatment efficiency for anaerobic digestion of lignocellulosic substrates. (December 2015)

• Record Type: Journal Article
• Authors: Peces, M.; Astals, S.; Mata-Alvarez, J.
• Is Part Of: Waste management. Volume 46(2015)
• Page Start: 189
• Page End: 196
• Publication Date: 2015-12
• Subjects: Anaerobic digestion -- Pre-treatment -- Ultrasonication -- Thermal -- Energy crops; Hazardous wastes -- Periodicals; Refuse and refuse disposal -- Periodicals; 363.728
• DOI: 10.1016/j.wasman.2015.08.022
• Languages: English
• ISSNs: 0956-053X

Abstract

Highlights: Total solid concentration is a significant parameter in pretreatment optimisation. Optimal total solid was 100 g kg −1 for ultrasound and low-temperature pretreatment. Modelling was used to compare pretreatments effects over lignocellulosic substrate. Pretreatment at 60 °C was mainly linked to enzymatic rather than thermal effects. Higher biodegradability was not correlated to higher ultrasonic energy supplied. Abstract: The present study evaluates the effect of moisture in low-temperature and ultrasound pretreatment on lignocellulosic substrates anaerobic biodegradability, where brewer's spent grain was used as model substrate. Besides moisture content, low-temperature pretreatment was also evaluated in terms of temperature (60–80 °C) and exposure time (12–72 h). Likewise, ultrasonication was also evaluated in terms of specific energy (1000–50, 000 kJ kgTS −1 ). In addition, the effect of substrate particle size reduction by milling pretreatment was also considered. The results clearly demonstrated that substrate moisture (total solid concentration) is a significant parameter for pretreatment performance, although it has been rarely considered in pretreatment optimisation. Specifically, moisture optimisation increased the methane yield of brewer's spent grain by 6% for low-temperature pretreatment (60 °C), and by 14% for ultrasound pretreatment (1000 kJ kgTS −1 ) towards the control (without pretreatment). In both pretreatments, the experimental optimum total solid concentration was 100 gTS kg −1 . Thus, lowering substrate moisture, a strategy suggested attaining energetic pretreatment feasibility, needs to be analysed as another pretreatment variable since it might have limited correlation. Finally, a preliminary energetic balance of the pretreatments under study showed that the extra methane production could not cover the energetic pretreatment expenses.