Suitability of biochar as a matrix for improving the performance of composting toilets.

To evaluate the suitability of biochar (rice husk charcoal) as a matrix in composting toilets that can decompose human faeces and recover fertiliser components, the composting process during toilet operation and the agricultural value of the resulting compost were characterised by performing a comparison with sawdust, rice husks, and corn stalks. The faecal decomposition ratio in biochar was 42%, similar to the values for rice husks (46%) and corn stalks (41%), but higher than the value for sawdust (25%). Heterotroph micro-organism acidity is qualitatively higher in biochar than in sawdust. However, nitrogen loss in biochar was 19%, lower than that in rice husks (36%) and corn stalks (25%), but similar to that in sawdust (16%). Although the biochar compost had no significant impact on the cation exchange capacity and water retention of sandy soil, the ratio of nitrogen transportation into plants was 12.8%, higher than that for the other materials. These results suggest that biochar is effective for achieving high faecal decomposition, low nitrogen loss, and high nutrient supply.

Direct measurement of energetic electron flow in Q-shu University experiment with steady-state spherical tokamak.

In magnetized plasmas, the presence of a significant number of energetic electrons has been observed but quantitative characteristics of these electrons are proving difficult to investigate. A Langmuir probe offers a means to provide quantitative measurement of these energetic electrons that takes into account electron emissions (secondary electron emission and electron reflection) from the probe tips and sheath expansion around the probe tips caused by a considerable negative potential. In this paper, these effects are experimentally confirmed and an analytical means to measure energetic electron characteristics are proposed. An analysis of plasmas produced by a high frequency wave is then applied leading to the successful detection of an asymmetric flow of energetic electrons. The estimated electron temperature and current density were approximately 4-5 keV and 2-3 kA/m(2).