Department of Civil Engineering, Kwame Nkrumah University of Science and Technology, PMB, UPO, Kumasi, Ghana.
Department of Chemical Engineering, Kwame Nkrumah University of Science and Technology, PMB, UPO, Kumasi, Ghana.
Sci Rep. 2021 Sep 7;11(1):17803. doi: 10.1038/s41598-021-97016-w.
On-site dry sanitation facilities, although cheaper than wet sanitation systems, suffer from high malodour and insect nuisance as well as poor aesthetics. The high odour deters users from utilizing dry sanitation toilets as an improved facility leading to over 20% open defecation in Sub-Saharan Africa. To address this malodour concern, this study first assessed odour levels, using hydrogen sulphide (HS) and ammonia (NH) as indicators, on two dry sanitation facilities named T1 and T2. The potential of using biomass (sawdust, rice husk, moringa leaves, neem seeds), ash (coconut husk, cocoa husk) or biochar (sawdust, rice husk, bamboo) as biocovers to remove or suppress odour from fresh faecal sludge (FS) over a 12-day period was investigated. Results showed that the odour levels for HS in both T1 (3.17 ppm) and T2 (0.22 ppm) were above the threshold limit of 0.05 ppm, for unpleasantness in humans and vice versa for NH odour levels (T1 = 6.88 ppm; T2 = 3.16 ppm; threshold limit = 30 ppm limit). The biomasses exhibited low pH (acidic = 5-7) whereas the biochars and ashes had higher pHs (basic = 8-13). Basic biocovers were more effective at HS emission reduction (80.9% to 96.2%) than acidic biocovers. The effect of pH on suppression of NH was determined to be statistically insignificant at 95% confidence limit. In terms of HS and NH removal, sawdust biochar was the most effective biocover with odour abatement values of 96.2% and 74.7%, respectively. The results suggest that biochar produced from locally available waste plant-based materials, like sawdust, can serve as a cost-effective and sustainable way to effectively combat odour-related issues associated with dry sanitation facilities to help stop open defecation.
现场干式卫生设施虽然比湿式卫生系统便宜，但存在恶臭和虫害滋扰以及美观性差等问题。恶臭会阻止使用者将干式卫生厕所作为一种改良设施来使用，导致撒哈拉以南非洲地区超过 20%的人仍在露天排便。为了解决这个恶臭问题，本研究首先使用硫化氢 (HS) 和氨 (NH) 作为指标，评估了两种名为 T1 和 T2 的干式卫生设施的恶臭水平。本研究还探讨了使用生物质（木屑、稻壳、辣木叶、蓖麻籽）、灰（椰子壳、可可壳）或生物炭（木屑、稻壳、竹子）作为生物覆盖物，在 12 天内去除或抑制新鲜粪便污泥 (FS) 中恶臭的潜力。结果表明，T1（3.17 ppm）和 T2（0.22 ppm）的 HS 恶臭水平均高于 0.05 ppm 的人类不适阈值，而 NH 恶臭水平则相反（T1=6.88 ppm；T2=3.16 ppm；阈值=30 ppm）。生物质的 pH 值较低（酸性=5-7），而生物炭和灰的 pH 值较高（碱性=8-13）。碱性生物覆盖物对 HS 排放的减少更有效（80.9%至 96.2%）。在 95%置信限内，pH 对 NH 抑制的影响被确定为无统计学意义。就 HS 和 NH 的去除而言，木屑生物炭是最有效的生物覆盖物，其臭味衰减值分别为 96.2%和 74.7%。结果表明，利用木屑等当地可用的废植物材料生产的生物炭，可以作为一种具有成本效益和可持续的方式，有效解决与干式卫生设施相关的恶臭问题，有助于停止露天排便。
