Composting of pic Faeces with corn stalks in China - Microbiological examinations; hygienic aspects and sanitation capacity

With the increasing demand for meat (pork) the pig production in China increased over the last years,especially in the Northern East of China around mega cities like Beijing. Increasing pig production in large scale pigfarms head to enormous amounts of organic wastes (such as pig faeces), over-fertilization of agricultural areas andenvironmental pollution in regions with high pig production and density.

Further Authors:
Wang M., He C., Ling Y., Liu Y - China Agricultural University

Pig manure can contain pathogens with risksfor animal health, public human health and the environment.Objectives: Composting is biotechnological treatment and a possibility to produce a fertilizer in consideration ofhygienic safety which could be transported to agricultural areas in regions far away from these mega cities. In order toprotect soil and plant quality the agronomic efficiency and hygienic safety of such fertilizer must be demonstrated priorto their application on cultivated fields. The challenge was to determine the sanitation capacity of different variants ofcomposting processes, especially under winter conditions in Beijing (China), and to estimate the microbiological riskfor human health, animal health and the environment.Material and methods: Pig manure and corn stalks were used for composting (ratio 1:7) carried out in small rottingboxes (1m3). The six variants of composting differed in turning interval (no turning, turning once and turning twice aweek) and cover. Two boxes were the same in turning interval, one covered and one uncovered. The composting trialran for ten weeks without forced aeration. As test organism heat resistant strain Salmonella Senftenberg W775 (H2Snegative) (called “W775”) and as indicator organism faecal streptococci were used for microbiological examinations inthe experiment. Mixed input materials were inoculated with a suspension of test organism “W775” and put in sterilesacks. These served as test carriers and were inserted in the rotting boxes in three different positions, representative forparts of the rotting boxes with different risks for hygienic safety. During experiment, qualitative and quantitativeexaminations were carried out to determine the presence of “W775” and faecal streptococci in control and test sampleson day 0, 14, 49 and 70. Data logger were used for temperature measurements on each position of test samples.Temperature, dry matter content and exhaust gas composition were regularly monitored.Main result, brief discussion and conclusion drawn: The numbers of “W775” in the control and starting sample in thebeginning of experiment were 107 cfu/g. The “W775” was not detectable after 14, 49 and 70 days of composting in allof the tested samples. In the positive control samples, stored at room temperature, “W775” was still detectable more orless without any decrease by orders of magnitude over the whole composting period. In regard to the sanitation capacitythe temperature and other influences of composting procedure at each position in every box seem to be sufficient toinactivate the heat resistant strain “W775” in our test samples in all six variants of composting. In conclusioncomposting in this way is a suitable treatment for organic wastes to produce a fertilizer in consideration of hygienicsafety. These fertilizer can be used to export nutrients from areas with high animal density to other regions, far away, with a minimized microbiological risk.



Copyright: © European Compost Network ECN e.V.
Source: Orbit 2012 (Juni 2012)
Pages: 6
Price: € 6,00
Autor: René A. Eling
Dr. Werner Philipp
Ludwig E. Hoelzle

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