Study on the feasiblity of using corn stem as a matrix in bio-toilet

摘要

In this paper we experimented on corn stem as a matrix in bio-toilet to decompose feces and livestock manure.To determinate the efficiency in decomposing feces and manure, we design two experiments: Experiment 1: using corn stem to decompose human wastes, and Experiment 2: using corn stem to decompose cattle manure. Experiment 1: The tank (about 15 liters) with a writhing gear is filled with corn stem (2kg, dry) ,1-2cm size. Two students used the bio-toilet every day for thirty days. The daily averaged adding of feces was 0.22kg (dry). Faces-corn stem temperature 55℃ and Water content 55%; Faces-sawdust 55℃ and Water content 57%.Conclusions: (1)Reduction of weight: The rate of total weight reduction of feces-corn stem mixture (79.7% )is higher than feces-sawdust mixture(70.2 %).(2)Nitrogen And Phosphorous: Finally, nitrogen in two mixtures is 81.76g/kg and70g/kg respectively. (3)Organic matter: At the thirtieth day, organic matter in corn stem and sawdust mixture is 776g/kg and 815g/kg espectively. (4)pH: pH in the feces -corn stem mixture changed from 7.55 to 8.25, which is consistent with feces-sawdust mixture basically. Experiment 2: The treatment of cattle manure was conducted in a 25 liters bio-toilet reactor. To study the differences, two experiments were carried out: one used sawdust totally and another used a mixture of half sawdust and half corn stem. The moisture maintained the range of 40%-70% in both experiments. Cattle manure was then fed at the rate of 2.5 kg/d daily. The temperature fluctuated around 50-60℃. Conclusions:(1)Weight reduction: The maximum cattle manure loading was 85 kg (2.5kg/d, accumulation of 45 days).The ratio of reduced weight to original one of total materials was 75.14% in the first experiment 1, and it was 78.38% in the second one.(2) N+P_2O_5+K_2O: Both experiments, N, P, and K contents were significantly increased until 35th day but changed little after 35th to 45th day.(3) Organic matter: The initial C/N ratios are 59.46 and 72.86 respectively. After 45 days of experiment, it rapidly reduced to 13.78 and 16.83 respectively.(4) PH: The light change in pH during the both experiments, and, finally remained at 8.34 and 9.96 respectively. From above experiments, we can draw that (1) Using of corn stem as matrix can decompose human feces and manure efficiently. (2) Corn stem can replace sawdust as matrix in a bio-toilet. In some respects it is over sawdust matrix. (3) The remains of feces-corn stem mixture has high nitrogen, phosphorous, and organic mater etc.. It is suitable fertilizer for soil.