In this study anaerobic digestion of selected lignocellulosic substrate, namely brewery spent (BSG), was studied. In order to facilitate anaerobic digestion several types of pretreatrment methods were tested such as: mechanical, chemical (alkali anc acid) and thermo-chemical. The anaerobic digestion experiments were carried out in asemi-continuous stirred bioreactors with the organic loading rates between 2.9 and 3.9 kgCODm-1d-1 (1.9 and 2.5 kgvss m-3d-1 respectively) and corresponding hydraulic retention times of 33-39 days. Biogas production and composition, pH, COD, TSS and VSS, short chain fatty acids and phenolic compounds were measured. A significant inhibition of biogas production occured, depending on the type of substrate pretreatment. There are indications that p-cresol is responsible for process inhibition when its concentration in the reaction mixture exceeds critical value between 115 and 240 mlL-1. Anaerobic digestion of chemically pretreated BSG (acid and alkali) and untreated-raw BSG was inhibited between the days 56 and 63 of the experiment, followed by thermo-chemically pretreated BSG on day 112 and mechanically pretreated BSG on day 126. Analyses of the substrates showed no phenolic compounds either in raw-untreated BSG or pretreated substrates, therefore the recorded p-cresol is an intermediate degradation product, responsible for process inhibition.
COBISS.SI-ID: 2833032
The legislation on waste thermal utilization in Slovenia was markedly complicated in the year 2008; the main problems are related to minimal calorific value, relative high heavy metals content (especially mercury) and high sulphur content. Sulphur and cadmium are not among the limiting parameters of the noted technical specification for alternative fuels, so the new regulation in Slovenia will be appealed.
COBISS.SI-ID: 4256282
High methane production potential of lignocellulosic substrates (like brewery wastes) in an anaerobic degradation process deserves special research concern. Relatively high content of lignin, however, much affects degradation through its fitotoxic degradation products and thus limits the rate of degradation of major component - structural polysaccharides. In this paper differences in biogas production from mechanically and chemically pretreated brewery spent grain (BSG) will be presented and critically discussed. As a substrate a combination of brewery wastewater and brewery spent grain was used. Pilot-scale semi-continuous bioreactors operated in mesophilic conditions in the experiments. The performance of the reactors was monitored by measuring the following parameters: biogas production and pH (recorded daily), volatile fatty acids, chemical oxygen demand, ammonia-N (recorded weekly). In addition to these parameters lignin degradation products like phenol and alkylphenols were analysed. Inhibition of biogas production due to the cummulative diverse effects of degradation products in the fully loaded methanogenic reactor was also studied.The inhibition occurred, due to the inhibitory effects of lignin and its degradation products on certain functional groups of anaerobic bacteria and archaea. The differences between mechanically and chemically pretreated BSG were demonstrated during anaerobic degradation. The results suggested that the anaerobic digestion of mechanically pretreated BSG is more effective than anaerobic digestion of chemically pretreated BSG. Decrease in biogas production of mechanically pretreated BSG was detected later (after 126 days) than in anaerobic digestionof chemically-alkali and acid pretreated BSG (77 days). Average biogas production in mechanically pretreated BSG was 19,97 ml/min, in alkali pretreated BSG 19,02 ml/min and in acid pretreated BSG 18,70 ml/min.
COBISS.SI-ID: 4552218
The regulation about processing non-hazardous waste into solid fuel (UL RS št. 57/2008) has set the conditions for such processes (procedure of waste treatment by R12 to R13), before this waste is used as fuel (procedure R1). Regulation states that only non-hazardous waste is allowed to be processed into solid fuel. This includes wastes with the classification number 19 08 05 - which is excess sludge from wastewater treatment plants (hereinafter referred to as sewage sludge). This type of waste represents the largest proportion of wastes at municipal wastewater treatment plants. It originates from the increment of active sludge produced at aerobic biological waste water treatment.
COBISS.SI-ID: 35452677
The chapter mostly focuses on municipally produced organic wastes as well as municipal sludge and organic farm waste. Its origin, classification and quantities produced in a modern society are presented. The main focus is aimed at possibilities of anaerobic treatment of each type of waste in order to produce biogas, which can be used as a renewable energy resource. In this chapter currently available and emerging technologies are presented which are able to successfully treat waste substrates to biogas.
COBISS.SI-ID: 4904218