Browsing by Author "Awuah Esi"

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    Measurement of Odour in On-Site Sanitation Systems in Low-Income Settings
    (Springer, 2016) Appiah Obeng Peter; Oduro-Kwarteng Sampson; Keraita Bernard; Bregnhøj Henrik; Abaidoo R. C; Awuah Esi; Konradsen Flemming
    The objective assessment of the level of odour in on-site sanitation systems is required when evaluating emerging technology options and maintenance practices. The purpose of this study was to measure the concentrations of hydrogen sulphide and ammonia as surrogates of odour using a portable gas detector, and assess whether the concentrations of the compounds correlate with the perception of users of the facilities. The Aeroqual 500 portable gas detector with hydrogen sulphide and ammonia sensor heads was used to measure the concentrations of the compounds in 88 private and seven communal latrines sampled from a peri-urban community in Ghana. The odour perception of 189 and 165 users of private and communal latrines, respectively, was assessed on an ordinal scale. It was found that the concentrations of hydrogen sulphide and ammonia measured with the gas detector reflected the known variation of odour levels among different technology options and the perceptions of the latrine users. The concentrations of hydrogen sulphide measured in the water closet, ventilated improved pit (VIP) and the simple pit latrines were 0.01, 0.03 and 0.13 ppm, respectively; those of ammonia were undetected for the water closet, and 0.30 and 3.27 ppm for the VIP and simple pit latrines, respectively. The Pearson correlation coefficient between hydrogen sulphide concentrations and user perception of odour (−0.234) was significant at 5 % level (p = 0.022) but that for ammonia was not. The results indicate that a portable hydrogen sulphide detector may be employed to objectively assess the effectiveness of new latrine designs and maintenance practices aimed at reducing odour in latrines.
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    Optimising ventilation to control odour in the ventilated improved pit latrine
    (Springer, 2018) Obeng Peter A.; Oduro‑Kwarteng Sampson; Keraita Bernard; Bregnhøj Henrik; Abaidoo R. C; Awuah Esi; Konradsen Flemming; 0000-0002-1235-2252
    The rate of ventilation through the vent pipe of a ventilated improved pit latrine is the main technical factor that determines its efficiency in odour control aside the maintenance and cleaning practices of the users. Even though the factors affecting the ventilation rate have been well researched, they have not been previously related in a mathematical model to quantify the relative effect of the various factors on the ventilation rate. The objective of this paper is to develop such a model that could be used to optimise and predict the ventilation rate as a function of relevant design criteria and weather conditions. The ventilation rates produced by various design modifications in an experimental ventilated improved pit latrine were measured under monitored weather conditions. A linear regression model was used to assess the relative effect of the various design modifications and the elements of weather on the ventilation rate. It was found that the diameter of the vent pipe is the most important factor which accounts for 53% of variations in the ventilation rate, followed by the external wind speed, which accounts for 25% of changes in ventilation. The provision of windows in other sides of the superstructure other than the windward side leads to a reduction of 32% in the ventilation rate and accounts for 9% of the variations in the ventilation rate. A regression model developed in this study could be used to optimise and predict the ventilation rate based on a set of design criteria and meteorological data.