Feces collection and composting technological design on scaled beef cattle farms

Abstract: Since the rapid development of livestock breeding industry, the amount of livestock manure discharge, which contains large amounts of nutrients and harmful ingredients, has increased rapidly in China. If these livestock manures are not treated timely, the environment would be polluted seriously, which would also in turn prevent the development of livestock breeding industry. A law named "Regulation on prevention and control of pollution in livestock and poultry breeding", issued by the State Council of the People's Republic of China, points out that livestock and poultry farms must build waste treatment facilities since January 1st, 2014. At present, therefore, controlling pollution has become the most important thing for livestock breeding industry in China.There are two kinds of feces cleaning technologies including Dry Cleaning Technology (DCT) and Water Flushing Technology (WFT). In DCT, the feces and urine are separated and collected at the breeding house, and then are used as the composting material and liquid fertilizer, respectively. This technology has become the main feces cleaning way in China due to its high efficiency in saving water and reusing the waste matter. In this study, the formula for feces collection on scaled beef cattle farms using DCT was analyzed and summarized through investigating formulas for calculating: 1) the feces amount from one adult cattle; 2) the feces amount from all cattles on a cattle farm; and 3) feces collection. After feces collection, the efficient composting technology was designed through determining: 1) the calculation of material balance; 2) the main parameters controlling composting process; 3) the main workshop sizes (e.g. the raw material workshop, the first fermentation workshop, the second fermentation workshop, the product storage workshop, the biological aerated filter and other auxiliary workshops); and 4) the main equipments used in composting. To easily understand, the feces amounts were calculated based on a given breeding scale, i.e., a farm with 10 thousands of beef cattles. The results showed that the feces amounts of scaled beef cattle farms using DCT can be calculated by the cattle number and that the collection rate coefficient was 0.83, resulting in about 150 t feces with 82% moisture for a farm with 10 thousand beef cattles. A total of 210 t raw materials (150 t cattle feces mixed with 60 t additive, adjusting moisture content to 60% based on wet weight) can produce 93.04 t end-products after composting. In addition, the composting project covers an area of 17 738 m2, and the whole system can be operated automatically by a set of special equipments.