Physico-chemical characteristics of fresh faecal matter from a residential apartment: a short-term study conducted at Thiruvananthapuram, Kerala, India

The study presents findings from physico-chemical and elemental analyses of fresh faecal matter from a residential apartment in Thiruvananthapuram, Kerala, India. Samples were taken every 8–10 days over 4 months to account for variability and establish baseline data. The study also examines the influence of dietary patterns and toilet cleaners on faecal sludge properties. Key results include high values of chemical oxygen demand (1850 ± 50 mg/L), total suspended solids (866.6 ± 200 mg/L), total Kjeldahl nitrogen (67.5 ± 20 mg/L), potassium (62.9 ± 10 ppm), sodium (49.1 ± 12 ppm) and iron (30.2 ± 15 ppm). Elemental analysis revealed carbon (31.62%), hydrogen (4.51%), nitrogen (2.32%) and sulphur (2.22%), with a C: N ratio of 13:1. Common and heavy metals were also measured, including sodium (49.1 ppm), magnesium (16.1 ppm), potassium (62.9 ppm), iron (30.29 ppm), aluminium (8.64 ppm), calcium (4.70 ppm), lead (0.32 ppm) and silver (1.14 ppm). These findings are significant for the scientific community and practitioners in designing effective treatment processes to replace septic tanks or soak pits, especially relevant for coastal regions where 37% of the global population lives at a population density twice the global average.