Characterization of pit latrines to support the design and selection of emptying tools in peri-urban Mzuzu, Malawi

Abstract

The urban areas of many low-income countries must balance a rising demand for pit latrines for household sanitation provision against limitations in space, resulting in a need for pit latrine emptying services. This study was undertaken in the peri-urban neighborhood of Area 1B in the city of Mzuzu, Malawi, to examine the characteristics of household pit latrines for designing and selecting pit latrine emptying tools. We used 150 structured household surveys and field observations. From this, a subset was selected and 30 manual cone penetrometer tests were conducted at full latrines.Chemical oxygen demand analysis was also performed for 14 pit latrines. The results indicated that in addition to serving as a disposal for fecal matter, 90% of households also used pit latrines for domestic waste. Only 10% of the studied pit latrines were lined. The filling rate in the study area is calculated to be about three years, and no respondents reported previous emptying. It is suggested pit latrine emptying technology development focuses on a maximum tool diameter of 10 cm to fit through the keyhole (squat hole) and height of 146 cm to fit inside the superstructure, as well as supporting unlined pits and the ability to pump trash.

Characterization of Faecal Sludge from Pit Latrines to Guide Management Solutions in Cape Coast, Ghana

“…The COD results in this study fall within the range reported in Ghana (49,000-85,998 mg/L) [29,30] but higher (4.7 times) than those reported in Ouagadougou (12,437 mg/L) [8]. On the contrary, the results are lower than those reported in Kenya (112,800 mg/L) [31] and Malawi (45,447 mg/L) [32]. The results from Cape Coast are far higher than that of septage [23] and the Ghana EPA effluent discharge standard.…”

Re-evaluating the strength of pit-latrine faecal sludge from dynamic cone penetrometer test data

“…Our results indicate that faecal sludge has a wide strength range, possibly dependent on age, usage practices, pit construction details and the extent to which latrine pits are used for general waste disposal. The faecal strengths observed throughout Chiposa et al (2017), Chirwa et al (2017 and Seal et al (2018) are, however, substantially higher than those which have been previously reported.…”

“…The pit latrine is an on-site sanitation solution whereby excreta is deposited through a drop hole into a below-ground pit, often alongside anal cleansing materials and menstrual cloths, amongst other solid waste. Pit latrines are often used for domestic waste disposal in many areas (Chiposa et al 2017). In densely populated informal settlements, space limitations necessitate that pits are emptied once they become full; this contrasts with most rural areas, where full pits can be covered with soil and replaced by a new pit in a different location.…”

“…The cone used in the tests described here was 55 mm long and 35 mm in diameter, as used in the penetrometer developed by North Carolina State University and used bySeal et al (2018), Chirwa et al (2017 andChiposa et al (2017). The drive rod had a diameter of 16 mm, leading to the masses of penetrometer components shown inTable 1.…”

Comparative risk of pit latrine sludge from unplanned settlements and wastewater in Mzuzu City, Malawi

“…The higher levels of organics and nutrients in pit latrine sludge as compared to wastewater can be explained by the dilution in wastewater whose major constituent is water. In addition, the disposal of solid waste and use of additives in pit latrines, which is unlikely to happen in the wastewater stream, could also be attributed to the difference (Kalulu et al, 2016;Chiposa et al, 2017). The major forms of solid waste thrown into pit latrines included paper, cobwebs and vegetative waste.…”