| Compared with the traditional methods, using earthworm to treat agricultural biosolids has many advantages such as higher efficiency, better economic benefits, and cleaner environment effects and so on. The main agricultural wastes are pig manure and rice straw in Zhejiang province. Those two kinds of wastes were treated separately with traditional methods, whereas earthworm could combine and took both advantages of them. The aims of this thesis were to find the optimal matching of the mixture, which showed in C/N, and to find the contribution of earthworm in the process of composting by maturing the change of nutrition content of the mixture. Another important aim was to evaluate the rotted rate of the mixture and test the consistency of the rotted indexes by choosing proper rotted indicators.Two experiments were designed to fulfill the purpose. The first one lasted for 90 days. Four treatments C/N 20,C/N 25,C/N 30 and C/N35were settled. The regular pattern of growth of earthworm was evaluated by average individual weight daily and multiple individual weights daily. The regular pattern of reproduction was evaluated by daily cocoon production and accumulated cocoon production. The second experiment lasted for 35 days. Three treatments C/N 25,C/N 30 and C/N35 with earthworm were settled, while three treatment C/N 25,C/N 30 and C/N35 without earthworm were settled as contrasts. The change of nutrition content of the mixture was measured by the properties NH4-N, TN and TOC. Lignin/cellulose ratio,pH,DOC and C/N ratio were used to evaluate the rotted rate of the mixture and the consistency of the rotted index.The experiment conclusions were as follows:(1) The regular growth and reproduction patterns of E.fetida:0 d-90 d was growth period, while 30 d-90 d was reproduction period. According to four indexes: average weight, Multiple of increasing weight, daily cocoon production and accumulated cocoon production, the most suitable C/N for growth and reproduction of E.fetida was 30.(2) Changes in nutrition content:the content of NH4-N declined in all the treatments. When the C/N were 25 and 35, the differences between treatments with and without earthworms were significant. When C/N equaled 25, the declined rate was the highest in treatment with earthworms. The content of TOC declined in all the treatments, and the difference between C/N 25 and C/N 30 was significant in treatments with and without earthworms. The content of TN increased in all the treatments. The increase of TN content in treatments without earthworms was higher than that with earthworm, the difference was significant. When C/N was 30, TN increased the most rapidly in treatment with earthworms.(3) The rotted rate of the mixture:lignin/cellulose declined in the mixture. Treatment C/N 30 with earthworms was the best in the degradation of cellulose. pH appeared to rose first and then declined.21 day reached the minimum. All the mixture had yet not rotted for pH was above 7.5. The value of the DOC fluctuated in different treatments. Before day 21, DOC rose and then declined. After day 21, DOC rose slightly. The final DOC in all the treatment indicated that the mixture had not yet rotted. All values of C/N in the treatments declined. When C/N was 25, the declining rate was the most rapid in treatments with earthworms. There were four treatments (C/N 25 with and without earthworms, C/N 30 with and without earthworms) when in some period the C/N were under 20. According to traditional option the mixture were rotted. But according to DOC and pH, the mixture had not yet rotted. So this experiment testified that it's untrue to use C/N 20 as rotted standard index, there were some limitations in only using C/N to evaluate rotted rate of the mixture. |
PDF Full Text Request