A comparative study of anaerobic digestion of food waste in a single pass, a leachate recycle and coupled solid/liquid reactors

2003 ◽  
Vol 47 (1) ◽  
pp. 319-324 ◽  
Author(s):  
H.L. Xu ◽  
J.Y. Wang ◽  
H. Zhang ◽  
J.H. Tay
Keyword(s):  
Anaerobic Digestion ◽  
Food Waste ◽  
Methane Content ◽  
Anaerobic Sludge ◽  
Methane Fermentation ◽  
Two Phase ◽  
Single Pass ◽  
Digestion Process ◽  
Solid Liquid ◽  
Methanogenic Phase

A single pass reactor (R1), a leachate recycle reactor (R2) and a coupled solid/liquid bioreactor (R3-Rm) for anaerobic digestion of food waste were comparatively investigated in terms of digestion process and treatment efficiency. The coupled solid/liquid bioreactor is an enhanced two-phase system and distinctive from a traditional two-phase process with an upflow anaerobic sludge blanket (UASB) reactor as the methanogenic phase and a circulation of treated leachate between the acidification and methanogenic phases. In comparison with R1 and R2, R3-Rm enhanced the digestion process and increased the methane content of biogas. 100% of the R3-Rm methane yield was from the methanogenic phase with average methane content of 71%. The significant enhancement was also confirmed by the removal of 79% of total organic carbon (TOC), 60% of volatile solids (VS) and 80% of total COD in 12 days running of R3-Rm. However, no active methane fermentation was detected in R1 and R2 during 60 days operation. The results in this laboratory-scale study show that the rapid accumulation of volatile fatty acids (VFAs) due to the rapid acidification of food waste inhibits the development of effective methane fermentation in single pass and leachate recycle reactors. The coupled solid/liquid bioreactor is more efficient in converting food waste into methane and carbon dioxide.

A hybrid two-phase system for anaerobic digestion of food waste

2002 ◽  
Vol 45 (12) ◽  
pp. 159-165 ◽  
Author(s):  
J.Y. Wang ◽  
H.L. Xu ◽  
J.H. Tay
Keyword(s):  
Anaerobic Digestion ◽  
Food Waste ◽  
Batch Reactor ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Phase System ◽  
Bioreactor Landfills ◽  
Two Phase ◽  
Methanogenic Phase

A hybrid two-phase system, consisting of a solid waste reactor as the acidification reactor and a wastewater reactor, i.e. an upflow anaerobic sludge blanket (UASB) reactor, as the methanogenic reactor, for anaerobic digestion of food waste was investigated. After the pre-acidification stage, COD and total VFA removals in the methanogenic phase were in the ranges of 74-93% and 77-100%, respectively, while leachate COD and total VFA concentrations in the acidification phase decreased by 95% and 97-99%, respectively. Some 99% of the total CH4 generated was from the methanogenic phase with the CH4 content of 68-70%. About 77-79% of TOC, 57-60% of volatile solids and 79-80% of total COD were removed. The results of this laboratory-scale study show that the hybrid two-phase anaerobic batch reactor system is suitable for effective conversion of food waste into CH4 and CO2. The hybrid two-phase system can be further developed into an effective and efficient way to enhance waste stabilization in operating bioreactor landfills.

Semi-continuous anaerobic digestion of food waste using a hybrid anaerobic solid-liquid bioreactor

2003 ◽  
Vol 48 (4) ◽  
pp. 169-174 ◽  
Author(s):  
J.-Y. Wang ◽  
H.-L. Xu ◽  
H. Zhang ◽  
J.-H. Tay
Keyword(s):  
Anaerobic Digestion ◽  
Solid Waste ◽  
Food Waste ◽  
Biogas Production ◽  
Continuous Operation ◽  
Methane Content ◽  
High Rate ◽  
Uasb Reactor ◽  
Two Phase ◽  
Solid Liquid

A hybrid anaerobic solid-liquid (HASL) bioreactor was developed to enhance food waste conversion. The HASL bioreactor is a modified two-phase anaerobic digestion system with a solid waste reactor and a high-rate anaerobic wastewater reactor, which was a UASB reactor. In this study, the methanogenesis in the UASB reactor was investigated under a semi-continuous operation of the food waste digestion system. The HASL process, including 7 days of start-up and 23 days of semi-continuous operation followed by 6 days of batch operation, was commenced by loading 2.8 kg of shredded food waste. During the semi-continuous operation, 0.2 kg of the same waste was loaded daily. The leachate from acidification phase, i.e., solid waste reactor, remained acidic (pH 4.9-5.5) and high in total VFA (TVFA), 9,500-11,500 mg/L, and COD (8,000-11,800 mg/L) levels. In the methanogenesis phase, i.e., UASB reactor, effective TVFA and COD removals (88 ± 5% and 85 ± 7%, respectively) were obtained, while the methane content was 71%. At the end of operation, about 78% of VS added in the HASL bioreactor was removed, while TOC and total COD reductions were 78% and 79%, respectively. The results showed that the use of UASB reactor in the semi-continuous HASL system can enhance the methanogenesis process and increase the methane content in biogas production.

The Characteristics of the Mixed Sludge Supernatant by Mesophilic Two-Phase Anaerobic Digestion Process

2013 ◽  
Vol 295-298 ◽  
pp. 1393-1397
Author(s):  
Qi Wei Liu ◽  
Xiao Yu Zhang
Keyword(s):  
Anaerobic Digestion ◽  
Loading Rate ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Digestion Time ◽  
Two Phase ◽  
Digestion Process ◽  
Acidogenic Phase ◽  
Methanogenic Phase ◽  
Better Than

The mesophilic (35°C) two-phase anaerobic digestion ( TPAD) process was used to treat mixed sludge from primary sedimentation and secondary sedimentation tanks ( 1:3 ). The results show that when HRT is 10 days and organic loading rate is 1.5kgVS/ (m3•d), the upper-liquid COD of methanogenic phase and acidogenic phase increased along with time, but not obviously; The contents oSuperscript textf polysaccharides and proteins in upper-liquid multiplied increased with digestion time, polysaccharides and proteins in acidogenic phase upper-liquid were more than methanogenic phase; The value of CST became larger after being digested by mesophilic two-phase anaerobic digestion, but the dewaterability of sludge in methanogenic phase is better than acidogenic phase.

The positive effects of waste leachate addition on methane fermentation from food waste in batch trials

2015 ◽  
Vol 72 (3) ◽  
pp. 429-436 ◽  
Author(s):  
Wanli Zhang ◽  
Lei Zhang ◽  
Aimin Li
Keyword(s):  
Anaerobic Digestion ◽  
Food Waste ◽  
Volatile Fatty Acids ◽  
Methane Content ◽  
Methane Yield ◽  
Methane Fermentation ◽  
Mixture Ratio ◽  
Positive Effects ◽  
Stable Performance ◽  
Waste Leachate

The purposes of this study were to investigate the effect of waste leachate (WL) addition on batch anaerobic digestion of food waste (FW), and to examine the influence of mixture ratio on the co-digestion process. The results showed that anaerobic digestion of FW was greatly enhanced by WL addition, as indicated by the higher methane yield, higher methane content, more volatile solids (VS) destruction, and higher stability. Although WL was rich in volatile fatty acids (VFA), its addition did not cause VFA inhibition. It was found that WL addition was beneficial to accelerate the start-up and shorten the long reaction time of the batch anaerobic process. The time to reach the peak methane yield was reduced by 1, 2, and 4 days with WL addition. The optimum FW to WL ratio was 77.9:22.1 with the highest methane yield (416 mL/g VS), the highest methane content (64.3%), the greatest VS removal (77.6%), and stable performance. These results confirmed the positive effects of WL addition on methane fermentation from FW.

Enhancement of food waste digestion in the hybrid anaerobic solid-liquid system

2008 ◽  
Vol 57 (9) ◽  
pp. 1369-1373 ◽  
Author(s):  
X. Y. Liu ◽  
H. B. Ding ◽  
S. Sreeramachandran ◽  
O. Stabnikova ◽  
J. Y. Wang
Keyword(s):  
Anaerobic Digestion ◽  
Food Waste ◽  
Waste Treatment ◽  
Liquid System ◽  
Net Energy ◽  
Two Phase ◽  
Treatment Processes ◽  
Pre Treatment ◽  
Solid Liquid ◽  
Net Energy Gain

The hybrid anaerobic solid-liquid (HASL) system is a modified two-phase anaerobic digester for food waste treatment. To enhance the performance of anaerobic digestion in the HASL system, thermal pre-treatment (heating at 150°C for 1 h) and freezing/thawing (freezing for 24 h at−20°C and then thawing for 12 h at 25°C) were proposed for food waste pre-treatment before the anaerobic digestion. Both processes were able to alter the characteristics and structure of food waste favoring substance solubilization, and hence production of methane. However, there was no net energy gain when the energy required by the pre-treatment processes was taken into account.

Control Strategies for Enhancement of Anaerobic Digestion of Food Waste

2015 ◽  
Vol 1092-1093 ◽  
pp. 814-819
Author(s):  
Xiao Song ◽  
Meng Han ◽  
Qing Feng Gao ◽  
Guo Qing Yang ◽  
Yi Qi ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Food Waste ◽  
Methane Production ◽  
Control Strategies ◽  
Poor Performance ◽  
Two Phase ◽  
Anaerobic Digestion Process ◽  
Digestion Process ◽  
Waste Production ◽  
Fast Increase

Food waste management has become an important issue from the environmental, economic, and social points of view due to the fast increase of food waste production and serious environmental pollution. Food waste is considered to be an attractive feedstock of anaerobic digestion and has attracted worldwide attention because of its good biodegradability and high methane production potential. However, in practice, anaerobic digestion system of food waste often shows poor performance and stability, which greatly limited the development of anaerobic digestion process of food waste. In order to obtain high treatment efficiency and satisfactory methane yield, many researchers employed various control strategies for anaerobic digestion of food waste including pretreatment, additive agent addition, two-phase anaerobic digestion, and anaerobic co-digestion. Therefore, this article is intended to review the control strategies for anaerobic digestion process that have been developed for methane production from food waste.

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