Anaerobic Digestion Of Piggery Waste Research Articles

Comparative effect of biochar and activated carbon addition on the mesophilic anaerobic digestion of piggery waste in batch mode

A comparative study of the batch mesophilic anaerobic digestion of piggery waste was carried out with the addition of 5% biochar and 5% activated carbon. The results obtained showed that the bioreactors amended with biochar increased cumulative methane production, the kinetic constant for methane production and the COD removal efficiency compared to the control reactors and reactors with activated carbon addition. The maximum methane production and the kinetic constant were 6.9% higher in the reactors with biochar addition compared to the controls; while the COD removal efficiency was 3% higher in the case of biochar addition. In the case of activated carbon, only a slight improvement in anaerobic digestion performance was observed compared to the control.

Energy production from piggery waste using anaerobic digestion: Current status and potential in Cyprus

In this work the current status and the potential of biogas production and energy generation through the anaerobic digestion of piggery waste in Cyprus are presented. The onsite use of anaerobic digestion for treating piggery waste not only generates renewable energy, but it is also a sustainable waste management solution. The actual values of the biogas production (20,475 m3/day) and the energy generation are compared with the theoretical values, which are in line with several units. The value 20 m3/tonne of pig waste was found to predict more accurately the biogas, heat and electricity production compared to the value of 36 m3/tonne of pig waste. Moreover, an empirical equation (R2=0.9939) is proposed for calculating the biogas production per day, according to the volume of pig waste treated per day BGP=14.64 (PWT)+535. The potential biogas production from the total pig population of Cyprus equals to 29,734,356 m3/yr and the potential thermal and electrical energy are calculated to be 90.85GWhth/yr and 63.59GWhel/yr, respectively. Finally future alternatives on anaerobic digestion in Cyprus are presented such as co-digestion, centralized anaerobic digestion, hydrothermal pre-treatment, possible use of fuel cells and efficient utilization of pig slurry.

Effect of organic loading rate on the stability, operational parameters and performance of a secondary upflow anaerobic sludge bed reactor treating piggery waste

A study of anaerobic digestion of piggery wastewater was carried out in a laboratory-scale sludge bed reactor as a secondary treatment. The effect of organic volumetric loading rates ( B V) in the range of 1.0–8.1 g TCOD/l d on the process performance was evaluated. The best results were obtained at B V equal to or lower than 4 g TCOD/l d. At higher B V values, the removal efficiency of the process decreased suddenly. A linear relationship was found between the effluent SCOD and the TVFA/alkalinity ratio ( P). A relationship was found among the different operational variables ( B V, removal efficiency, effluent soluble COD, soluble COD removal rate ( R), retention factor ( φ), specific microbial growth rate ( μ), methane production rate per volume of reactor and per volume of waste treated–– Q M and q M, respectively) and the corresponding regression equations were obtained. An increase of B V determined a decrease of removal efficiency, φ and q M and an increase of effluent soluble COD, μ, R and Q M. The value of the maximum specific microbial growth rate ( μ M) determined through the equation that correlated B V and μ was found to be 0.19 d −1. This value was of the same magnitude as those reported in other works of anaerobic digestion of piggery waste.

Effect of natural and modified zeolite addition on anaerobic digestion of piggery waste

The effect of natural and modified zeolites on the anaerobic degradation of acetate and methanol was evaluated by the determination of specific methane productivity (SMP) in batch minidigesters of 50 mL at doses of 0.01, 0.05 and 0.1 g of zeolite/g of VSS. The effects of the different zeolite concentrations were determined by the results of the SMP. A kinetic characterization with data of accumulated methane gas volume was also carried out. In the second phase of the study, the effects of natural and nickel zeolite concentrations were tested with piggery waste in laboratory scale digesters of 2.5 L operating at semi continuous mode, by increasing the organic load applied from 0.2 to 22.0 g TCOD/d corresponding to organic loading rates (OLR) of 0.1-8.8 g TCOD/l x d. A greater effect of modified zeolite on SMP was observed, with an increase of 8.5 times with magnesium zeolite, 4.4 times with cobalt zeolite and 2.8 times with nickel zeolite. Two phases were defined in the kinetic study and an increase of more than 2 times the apparent constant of digesters with modified zeolites was observed in the second phase when compared to unmodified natural zeolite. Modified natural zeolite addition to digesters can allow an increase in the potential biodegradability of piggery waste solid fraction and/or a considerable reduction of digestion volume.

Effect of influent strength changes on the performance of a down-flow anaerobic fixed bed reactor treating piggery waste

Abstract A study of the anaerobic digestion of piggery waste was carried out in a laboratory-scale down-flow fixed bed mesophilic (26–30 °C) reactor working at different influent strengths, and hydraulic retention times (HRTs) from 5.0 to 1.25 days. Changes in the influent substrate concentration did not cause process failure. The system was capable of overcoming the variation of influent strength at a fixed value of HRT. The reactor also operated as an equalisation tank reducing the variation of effluent strength, making it more favourable for aerobic post-treatment. The system operated better as the HRT of the reactor and the buffering capacity of the wastewater increased. The system also operated at different influent substrate concentrations and HRTs to maintain the organic volumetric loading rate ( B v ) constant at values in the range of 1.5–1.9 and 3.0–3.4 kg COD/m 3 day. The system operated best at the lowest B v applied although the COD removal efficiency was near to 60% for the highest B v studied. The results obtained showed the feasibility of using the anaerobic fixed bed reactor at variable conditions of influent strength and flow-rate for piggery wastes treatment through anaerobic digestion.

Effect of substrate concentration and temperature on the anaerobic digestion of piggery waste in a tropical climate

A study of the effect of substrate concentration and temperature variation on batch anaerobic digestion of piggery waste was carried out in laboratory-scale completely mixed reactors. The variation of chemical oxygen demand (COD), total volatile fatty acids (TVFA), alkalinity, pH and methane production with digestion time followed the same pattern at mesophilic (35 °C) and ambient temperatures (16.8–29.5 °C). The process was more stable at mesophilic than at ambient temperatures. The rate of COD removal correlated with the digestion time through an equation of the Grau kinetic model type. An increase in the initial concentration of organic matter caused a reduction of COD removal rate. In addition, COD removal rates at ambient temperatures were significantly lower than those obtained at mesophilic temperature.

Influence of different natural zeolite concentrations on the anaerobic digestion of piggery waste

The effect of different natural zeolite concentrations on the anaerobic digestion of piggery waste was studied. Natural zeolite doses in the range 0.2–10 g/l of wastewater were used in batch experiments, which were carried out at temperatures between 27°C and 30°C. Total chemical oxygen demand (COD), total and volatile solids, ammonia and organic nitrogen, pH, total volatile fatty acids (TVFA), alkalinity (Alk) and accumulative methane production were determined during 30 days of digestion. The anaerobic digestion process was favored by the addition of natural zeolite at doses between 2 and 4 g/l and increasingly inhibited at doses beyond 6 g/l. A first-order kinetic model of COD removal was used to determine the apparent kinetic constants of the process. The kinetic constant values increased with the zeolite amount up to a concentration of 4 g/l. The values of the maximum accumulative methane production ( G m) increased until zeolite concentrations of 2–4 g/l. The addition of zeolite reduced the values of the TVFA/Alk ratio while increasing the pH values, and these facts could contribute to the process failure at zeolite doses of 10 g/l.

Enterobacterial and viral decay experimental models for anaerobic digestion of piggery waste

A laboratory study was conducted to determine effects of the continuous mesophilic anaerobic digestion of raw pig manure in two types of enteropathogenic microorganisms, bacterial and viral. Faecal coliforms (indigenous to pig manure) and coliphage f2 (ATCC 15766 B1) were used as a model for some indigenous enteropathogenic microorganisms. The study was completed with laboratory survival experiments in lagoon stabilization of raw pig manure, for both models. Experiments for f2 survival in cell-free synthetic medium were also carried out. The results show that the anaerobic digestion process is more effective in eliminating viral than bacterial particles. Some parameters related to the ultimate biogas yield and kinetics were also determined. Lagoon stabilization of raw pig manure provides a more suitable environment for the removal of faecal coliforms than does anaerobic digestion. Finally, it was concluded that volatile fatty acids appeared to be responsible for the elimination of faecal coliforms. The agent that causes f2 inactivation is not well identified, although in some cases it could be NH3 that seems to act as a vircidal agent.

A kinetic study of the anaerobic digestion of piggery waste using down-flow stationary fixed film reactors

In this paper the behaviour of the down-flow stationary fixed film digesters is studied at laboratory and bench scale. Several organic loading rates are applied to the reactors in order to examine the support surface behaviour. Specific support surfaces of about 50 m2/m3 void volume seems to be optimal. A set of experiments carried out in a continuous stirred reactor is used to fit the kinetic constants of the Chen and Hashimoto's model. The model is then used to assess its applicability to the DSFF digesters. The results show that its application, is possible as a first approximation.

Effects of disinfectants and antibiotics on the anaerobic digestion of piggery waste

The effects of disinfectants and antibiotics on the anaerobic digestion of piggery waste were investigated. The disinfectants Tego 51, Dettol, NaOCl and Creolin, and the antibiotics, chlortetracyclin, tylosin, erythromycin, chloramphenicol, bacitracin and virginiamycin were tested at different concentrations. At concentrations normally used in practice, no inhibitory effect on methanisation process was detected. However, higher concentrations of the antimicrobial agents. Dettol, Creolin, bacitracin and virginiamycin, markedly inhibited biogas production. In order to minimize possible digester failures, farmers are advised to respect the normal recommended dose and to use low-toxicity antimicrobial agents.

Anaerobic digestion of piggery waste using a stationary fixed film reactor

A fixed film digester with a 35 litre support void volume, treating piggery waste at 35°C, was capable of handling high organic loading rates and short hydraulic retention times without process failure. The digester had a film support made of fired potter's clay and a surface-to-volume ratio of 157 m 2m −3. It could be loaded to 18·7 kg Volatile Solids (VS) m −3 day −1 without substantial increases in volatile acid levels or a reduction in the quality of the digester gas. Maximum methane gas production was 3·8 m 3 (STP) m −3 day −1 and the conversion of Volatile Solids into methane decreased with decreasing hydraulic retention time.

Anaerobic digestion of piggery waste. 2. Start-up procedure

Anaerobic digestion of piggery waste. 2. Start-up procedure

Anaerobic digestion of piggery waste. 1. The influence of detention time and manure concentration

Anaerobic digestion of piggery waste. 1. The influence of detention time and manure concentration