Inhibition of ammonia and hydrogen sulphide as faecal sludge odour control in dry sanitation toilet facilities using plant waste materials

Abstract

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 (H2S) and ammonia (NH3) 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 H2S 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 NH3 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 H2S emission reduction (80.9% to 96.2%) than acidic biocovers. The effect of pH on suppression of NH3 was determined to be statistically insignificant at 95% confidence limit. In terms of H2S and NH3 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.

Research on Moringa (Moringa oleifera Lam.) in Africa

“…Further studies dealt with the role of moringa in addressing water and soil pollution . Indeed, moringa was used in the treatment of sewage sludges, wastewater, effluents, and different types of industrial wastes [ 111 , 137 , 215 , 219 , 229 , 246 , 311 , 391 ]. Studies in this respect, exploiting the potential of M. oleifera seeds as coagulants/flocculants, were carried out in Algeria [ 109 , 111 ], Kenya [ 229 ], Tunisia [ 391 ], Cameroon [ 137 , 140 ], Ghana [ 201 , 215 , 220 ], and Malawi [ 246 ].…”

Biochar as a Sustainable Product for the Removal of Odor Emissions - Mini Literature Review

“…In the first case, the research focuses mainly on the use of biochar to remove unpleasant odors from sanitary toilets and to store liquefied milk fertilizer. Senanu et al [41] while studying the possibilities of using biocarbon covers to remove and suppress the smell of fresh fecal sludge, showed that thermally processed sawdust is able to reduce the reduction of H2S and NH3 by 96.2 and 74.7%, respectively. It was shown that biochar produced from local waste biomass can be a cost-effective and sustainable way to combat odor problems in dry sanitation.…”

Autotrophic and Mixotrophic Growth of an Ammonia Gas-tolerant Bacterium, Paenibacillus lentus NH33 in Ammonia Gas

“…Odors are generally attributed to the production of various volatile compounds arising from the anaerobic decomposition of fecal matter. The number of complaints regarding odors from outdoor toilets, compost facilities, and livestock farms is increasing year-by-year [1]. Deodorization technologies can be classified into three categories, i.e., technologies employing chemical [2], physical, or biological treatment methods [3].…”