DATA-DRYING-ISOTHERM-FAECAL-SLUDGES.xlsx

<i>Sample Collection</i><i></i><br>On-site sanitary wastes were received from the Pollution Research Group, at the University of KwaZulu-Natal, South Africa. The sludges were collected from the following sources: a) anaerobic baffled reactor (ABR) at a decentralized wastewater treatment system (DEWATS); b) VIP latrines and c) urine-diverting dry toilet (UDDT). The DEWATS is a mixture of black water, greywater and human faecal sludges and it receives effluent from neighbouring households and communal ablution blocks in Fraser's informal settlement, Durban. Due to the limited size of the inlet of the DEWATS, samples were collected during pit emptying and using a vacuum truck. For representative sampling of the DEWAT, samples were collected from 3 zones (top, middle and bottom) of the settling tank (first compartment). The VIP samples were collected directly from a vacuum truck, following the emptying of a VIP pit in Bester informal settlement, located 25 km north of Durban. The FS sample from the UDDT was collected from Kwamashu, 20 km north of Durban, a facility that serves a single household. FS samples from the UDDT were collected manually from the top, middle and bottom using spades and forks. Large household waste (clothing, sanitary material, paper, etc.) found in the sludge were removed onsite. For consistent and representative sampling, bulk samples have been collected from multiple points, screened for materials larger than 5mm (using a sieve) and mixed to a uniform consistency. The samples were kept at 4ºC and couriered to Cranfield University in plastic bottles under the authorization of the Health Department of the Republic of South Africa, through the export permit with the reference J1/2/4/2. The collection and analysis of FS for this investigation were approved by the Biomedical Research Ethical Committee from the University of KwaZulu-Natal (Ethical Clearance Reference: EXM005/18). After collection, the faecal sludge samples were stored in a cold room at 4°C at the laboratory of the Pollution Research Group. The faecal sludge was shipped inside tightly sealed containers to avoid moisture loss. At Cranfield University, fresh human faeces (HF) was collected from a volunteer in a cardboard bowl with the sample contained in a plastic bag and container as approved by the Cranfield Research Ethics Committee Approval (CURES/2310/2017). Samples were stored at 4°C and brought to room temperature before analysis. To determine the initial moisture content of the samples, 5 g of the samples was weighed and dried at 105 ± 5°C in a hot air oven. Table 1 highlights the initial moisture content of the samples as received from the University of KwaZulu-Natal and Cranfield. <i>Thermogravimetric analysis</i> Under isothermal drying conditions, 40 mg of sample was thinly spread in a cylindrical aluminium crucible to a diameter of ~3 mm and weighed to an accuracy of ± 0.5 mg. Samples were subjected to controlled temperatures of 55, 105, 85, 155, 205°C in a thermogravimetric analyser (Model: <i>PerkinElmer TGA 8000™</i>). All experiments were carried out using an airflow rate of 40 mL/min. Prior to isothermal temperature, samples were raised from 30°C to the specified temperature at a rapid heating rate of 100^oC/min to minimise drying during the heating-up stage. Average results for triplicate analyses are presented for four (4) samples: ABR, HF, UDDT, VIP for 5 temperatures (55-205^oC).