The Characterization of Feces and Urine: A Review of the Literature to Inform Advanced Treatment Technology

Abstract

The safe disposal of human excreta is of paramount importance for the health and welfare of populations living in low income countries as well as the prevention of pollution to the surrounding environment. On-site sanitation (OSS) systems are the most numerous means of treating excreta in low income countries, these facilities aim at treating human waste at source and can provide a hygienic and affordable method of waste disposal. However, current OSS systems need improvement and require further research and development. Development of OSS facilities that treat excreta at, or close to, its source require knowledge of the waste stream entering the system. Data regarding the generation rate and the chemical and physical composition of fresh feces and urine was collected from the medical literature as well as the treatability sector. The data were summarized and statistical analysis was used to quantify the major factors that were a significant cause of variability. The impact of this data on biological processes, thermal processes, physical separators, and chemical processes was then assessed. Results showed that the median fecal wet mass production was 128 g/cap/day, with a median dry mass of 29 g/cap/day. Fecal output in healthy individuals was 1.20 defecations per 24 hr period and the main factor affecting fecal mass was the fiber intake of the population. Fecal wet mass values were increased by a factor of 2 in low income countries (high fiber intakes) in comparison to values found in high income countries (low fiber intakes). Feces had a median pH of 6.64 and were composed of 74.6% water. Bacterial biomass is the major component (25–54% of dry solids) of the organic fraction of the feces. Undigested carbohydrate, fiber, protein, and fat comprise the remainder and the amounts depend on diet and diarrhea prevalence in the population. The inorganic component of the feces is primarily undigested dietary elements that also depend on dietary supply. Median urine generation rates were 1.42 L/cap/day with a dry solids content of 59 g/cap/day. Variation in the volume and composition of urine is caused by differences in physical exertion, environmental conditions, as well as water, salt, and high protein intakes. Urine has a pH 6.2 and contains the largest fractions of nitrogen, phosphorus, and potassium released from the body. The urinary excretion of nitrogen was significant (10.98 g/cap/day) with urea the most predominant constituent making up over 50% of total organic solids. The dietary intake of food and fluid is the major cause of variation in both the fecal and urine composition and these variables should always be considered if the generation rate, physical, and chemical composition of feces and urine is to be accurately predicted.

A critical analysis of physiochemical properties influencing pit latrine emptying and feacal sludge disposal in Kampala Slums, Uganda

“…The addition of detergents and additives which may be chemical, microbiological and enzymatic in nature, which are used for sludge stabilization and odor reduction, as found out during the baseline survey, could have contributed to increased phosphorous content. The oxidation and hydrolysis of phosphorous produces phosphates which combine with available water producing a weak phosphoric acid hence changing the pH (Rose et al, 2015). In addition, decomposition processes occurring in the pit latrine convert the phosphorus into orthophosphates which leach out of the pit to the groundwater (Nyenje, 2014).…”

“…The 77.6% variance indicated that there was a variation within the parameters mainly because all the 55 pit latrines analyzed were used by different households living in different slums with various user habits. In addition, since their economic status is different, their diets are also different thus contributing to variation in FS properties (Rose et al, 2015;Zziwa et al, 2014;Nwaneri, 2009). The first principal component (PC1) accounted for 29.62% of the total variance and was positive and largely contributed to by moisture content (MC) and total solids (TS) and least due to Ash content (AC).…”

Microwaving human faecal sludge as a viable sanitation technology option for treatment and value recovery – A critical review

“…The moisture content in human faeces is between 63 and 86 per cent w/w (Rose et al, 2015), while urine is mainly composed of water: between 93 and 96 per cent w/w (Polprasert, 1995).…”

Spectrophotometric Determination of Malondialdehyde in Urine Suitable for Epidemiological Studies

“…[18,19] Creatinine and urea were prepared in concentrations higher than expected in human urine, i.e. values higher than normal (100 mM vs. 16 mM and 0.5 M vs. 0.39 M for creatinine and urea, respectively), [14,19] and underwent the same sample preparation procedure as described for urine samples. The spectra shown in Figure 3 indicate that, in fact, urea and creatinine do not significantly interfere with spectrophotometric or spectrofluorometric determination of MDA-TBA2 adduct.…”

“…[13] Urine composition varies due to differences in individual water balance, environmental conditions, physical exercise and nutrition [14] and the standard addition method provides reasonable means to account for possible matrix interference effects, i.e. recovery.…”