Production of volatile fatty acids through co-digestion of sewage sludge and external organic waste: Effect of substrate proportions and long-term operation

Volatile fatty acids (VFAs) are preferred valuable resources, which can be produced from anaerobic digestion process. This study presents a novel technology using β-cyclodextrins (β-CD) pretreatment integrated alkaline method to enhance VFAs production from codigestion of food waste and sewage sludge. Experiment results showed that optimized ratio of food waste to sewage sludge was 3 : 2 because it provided adequate organic substance and seed microorganisms. Based on this optimized ratio, the integrated treatment of alkaline pH 10 and β-CD addition (0.2 g/g TS) performed the best enhancement on VFAs production, and the maximum VFAs production was 8631.7 mg/L which was 6.13, 1.38, and 1.57 times higher than that of control, initial pH 10, and 0.2 g β-CD/g TS treatment, respectively. Furthermore, the hydrolysis rate of protein and polysaccharides was greatly improved in integration treatment, which was 1.18–3.45 times higher than that of other tests. Though the VFAs production and hydrolysis of polymeric organics were highly enhanced, the primary bacterial communities with different treatments did not show substantial differences.

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Responses in milk yield and composition to the inclusion of ammonium salts of short-chain fatty acids in the drinking water of dairy cows

Animal Science ◽

10.1017/s0003356100029068 ◽

1970 ◽

Vol 12 (3) ◽

pp. 503-512 ◽

Cited By ~ 2

Author(s):

P. Jackson ◽

J. A. F. Rook

Keyword(s):

Fatty Acids ◽

Drinking Water ◽

Milk Yield ◽

Volatile Fatty Acids ◽

Short Chain Fatty Acids ◽

Rumen Ph ◽

Long Term Experiment ◽

Jersey Cows ◽

Friesian Cows

SUMMARYThe effect of introducing a solution of fatty acids (consisting mainly of ammonium acetate) into the drinking water of Jersey and Friesian cows on the yield and composition of milk was investigated. In short-term experiments there were small increases in milk yield and in the yield of fat in Jersey cows receiving either a high-roughage or a high-concentrate diet and in Friesian cows receiving a high-concentrate diet. Friesian cows receiving a high-roughage diet gave no response. In a long-term experiment extending over 16 weeks of lactation with Jersey cows receiving a high-concentrate diet, there was no immediate effect on milk yield but a greater persistency and overall the yield of fat was increased by 5·9%.Inclusion of ammonia salts in the drinking water caused increases in the ammonia contents of rumen liquor and of blood but there was little effect on rumen pH or the volatile fatty acids of rumen liquor.

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Production of propionic acid-enriched volatile fatty acids from co-fermentation liquid of sewage sludge and food waste using Propionibacterium acidipropionici

Water Science & Technology ◽

10.2166/wst.2013.463 ◽

2013 ◽

Vol 68 (9) ◽

pp. 2061-2066 ◽

Cited By ~ 9

Author(s):

Xiang Li ◽

Hui Mu ◽

Yinguang Chen ◽

Xiong Zheng ◽

Jingyang Luo ◽

...

Keyword(s):

Fatty Acids ◽

Sewage Sludge ◽

Propionic Acid ◽

Food Waste ◽

Volatile Fatty Acids ◽

Biological Nutrient Removal ◽

Distribution Analysis ◽

Propionibacterium Acidipropionici ◽

Second Stage ◽

Fermentation Liquid

Volatile fatty acids (VFA), derived from sludge fermentation, have been used as one effective carbon source for biological nutrient removal, especially favorable with VFA containing with high levels of propionic acid. In this paper, a new fermentation method was employed to significantly produce the propionic acid-enriched VFA from the co-fermentation liquid of sewage sludge and food waste: including (1) mixing food waste with sludge in the anaerobic digester (the first stage) and (2) separating the mixture, sterilizing the first stage liquid and fermenting it after inoculation with Propionibacterium acidipropionici (the second stage). The effect of the key parameters including pH, the mixing ratio of the food waste and sludge, fermentation time and temperature of the first stage on the propionic acid-enriched VFA production (the second stage) was individually discussed. By the molecular weight distribution analysis, the comparison of the solubilisation and hydrolysis process in difference parameters was fully elaborated. The optimal combination of the parameters was then obtained. Finally, the propionic acid-enriched VFA fermentation was successfully conducted in a semi-continuous reactor using the first stage liquid from the optimal condition.

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