Effect of particle size and sodium ion concentration on anaerobic thermophilic food waste digestion

Abstract

Serial basic tests were conducted for the determination of fundamental kinetics and for the actual application of kinetic parameters to food waste digestion with precise measurement of methane production. The effects of food particle size and sodium ion concentration on the anaerobic thermophilic food waste digestion process were investigated. Results of serial tests for the determination of fundamental kinetic coefficients showed the value of k (maximum substrate utilization rate coefficient) and KS (half-saturation coefficient) as 0.24 hr-1 and 700 mg/L, respectively, for non-inhibiting organic loading range. The substrate inhibition coefficient (Ki) was 1000 mg/L for inhibiting organic loading range. No inhibition effect was shown until 5 g/L of sodium ion concentration was applied to the serum bottle reactor. However, the volume of methane gas was decreased gradually to the concentrations of more than 5 g/L of sodium ion applied. All sizes of food waste particle had the same constants (A: 0.45) but the maximum substrate utilization rate constant (kHA) was inversely proportional to particle size. As average particle size increased from 1.02 mm to 2.14 mm, kHA decreased from 0.0033 hr-1 to 0.0015 hr-1. Result reveals that particle size is one of the most important factors in anaerobic food waste digestion.

Techniques for Siloxanes Removal from Biogas Produced by Sewage Sludge Digestion

“…However, the exhaust gas should be further treated, because the components in the sludge would transfer into air flow and resulting to air pollution. The dosage of alkaline to sewage sludge would introduce positive iron (such as Na + ) to anaerobic digestion reactor and inhibit the growth of methanogens [18]. For sewage sludge, the VMS only account for 20%-25% of the total siloxanes, and the PDMS was the main components [19,20].…”

Uncoupling of liquid and solid retention times in anaerobic digestion of catering wastes

“…The two-stage mode has the advantage of regulating the loading of volatile fatty acids to the methanogenic stage, and is a strategy employed to minimise the likelihood of process upset due to rapid overproduction of VFA. Two-stage digestion has been used in many recent studies on the processing of market wastes and other food wastes containing primarily fruit and vegetables (Mtz.-Viturtia et al, 1995, Kim et al, 2000, Bouallagui et al, 2004, Parawira et al, 2004, Wang et al, 2005). In the current work, however, it was found that in the case of the HF reactors a one-stage system was sufficient to maintain stable VFA levels and a fair degree of robustness in the face of disturbance, when solids were maintained in the system while liquids were flushed through.…”

Organic Fraction of Municipal Solid Waste: Overview of Treatment Methodologies to Enhance Anaerobic Biodegradability

“…Liberated cell wall has increased surface area for improved contact with microorganism for enhanced biomethanation (Kim et al, 2000;Elliot and Mahmood, 2012). Thus, mechanical treatment techniques such as (i) sonication, (ii) high-pressure homogenization and (iii) steeping or maceration are conducted to reduce the particle size of the substrate.…”

“…Thus, mechanical treatment techniques such as (i) sonication, (ii) high-pressure homogenization and (iii) steeping or maceration are conducted to reduce the particle size of the substrate. It has been reported by Kim et al (2000) that rate of utilization of feedstock is firmly depends on its size inversely for microbial consumption. Also, if the size of substrate is large, chemical oxygen demand (COD) solubilization decreases and it may result in declined production of biogas (Esposito et al, 2011).…”

“…The fervor of zeolites concerning anaerobic assimilation procedures is their ability to adsorb salts especially ammonia, which acts as an inhibitor in the AD process . Kim et al (2000) contemplated hindrance because of the sodium particle dose on the AD bioreactor running on thermophilic zone of FW and stated that sodium at a concentration of >5 g/L brought about decrease in biogas generation. Sodium is more lethal to propionic acid utilizing microorganisms when contrasted with other VFA debasing microorganisms in the AD system (Soto et al, 1993).…”