Greywater data from urban households in Ouagadougou (Burkina Faso) and its comparative treatment by constructed wetlands

Mix greywater (laundry and dishwashing) were collected three times a week, from six representative households located in Zogona district of Ouagadougou (Burkina Faso) and transported to an experimental site located in the campus of University Joseph Ki-ZERBO. For each sampling date, the greywater collected from the six households were mixed before use. The treatment wetlands (one unplanted and two planted with local plant species, Andropogon gayanus and Chrysopogon zizanioides respectively) were fed with the mix greywater for three successive days and then operated without greywater addition for four days. Once a week, the raw greywater and treated samples from each wetland were collected for analysis. The samples were collected in sterile 500 mL glass bottles for microbiological analysis and 1,000 mL plastic bottles for physico-chemical analyses. Physico-chemical parameters such as pH, electrical conductivity (EC), temperature (T, °C), and dissolved oxygen (DO) were measured directly from the influent and effluent using a portable pH/EC/TDS/temperature meter (Hanna Instruments, Romania) and Oxi 3310 (WTW Germany GmbH) (APHA 1998). The five-day biochemical oxygen demand (BOD5), chemical oxygen demand (COD), suspended solids (SS), nitrate (NO₃⁻), nitrite (NO₂⁻ ), ammonia (NH₄⁺), ortho phosphate (PO₄³⁻) were determined according to the Standard Methods (APHA 1998). Fecal coliforms, Esherichia coli, and enterococci were used as fecal indicators to evaluate the removal of microorganisms. The spread plate method and Chromocult Coliform Agar ES medium (Merck KGaA, Germany) were used to evaluate fecal coliform and E. coli (44 °C for 24 h), while Slanetz and Barthley agar medium (Liofilchem srl, Italy) (37 °C for 48 h) was used for enterococci (APHA 1998).