**3. Chapter methods**

#### **3.1 The study area and selection of production mills**

The study was conducted in the Central Region of Ghana, which is one of the sixteen (16) first-level government administrative units of Ghana. There is only one functional large-scale palm oil processing plant in the Central Region. This affords small-scale mills the opportunity for greater access to oil palm for processing. Twenty-five (25) small-scale processing mills were selected from four (4) palm oil processing Metropolitan, Municipal and District Assemblies (MMDA) namely Cape Coast Metropolitan Area (CCMA), Abura Aseibu Kwamankese District (AAKD), Twifo Hemang Lower Denkyira District (THLDD) and Mfantseman Municipality (MfM) all in the Central region of Ghana. The MMDAs were strategically selected to ensure agro-ecological balance (forest zone, transition zone, and coastal savanna zone). A map showing the study area and location of the selected small-scale processing mills is presented in **Figure 4**.

**Figure 4.** *Map of the study area and sampling location.*

#### **3.2 Data collection methods**

Data for this chapter was collected through interviews, structured observations, and review of relevant literature. An interview guide was designed and pre-tested (using eight small-scale palm oil processers in the Twifo Atti Morkwa District, Central Region of Ghana) for use in the study. For each of the processing mills, the manager/mill operator and a worker/processer were interviewed using the interview guide. The structured observation technique was employed to corroborate the information obtained from the mill operators through the interviews.

#### **3.3 Wastewater characterization**

Wastewater samples were collected from four (4) small-scale palm oil processing mills from Abura Aseibu Kwamankese District in the Central Region of Ghana. Samples were taken from each of the processing mills during the lean palm oil production season (August 2019) and peak production season (March 2020). For each of the processing mills and in each season, samples of wastewater were collected separately from boiling and clarification tanks. Samples were collected in opaque plastic containers and labeled appropriately before transport to the Environmental Quality Engineering laboratory of the Cape Coast Technical University, Ghana for analysis.

The following parameters were measured: pH, total solids (TS), total suspended solids (TSS), total dissolved solids (TDS), chemical oxygen demand (COD), biochemical oxygen demand (BOD5), total nitrogen, phosphorus, potassium and oil and grease. The pH measurements were performed using Portable pH-meters XS Series. The solids content was determined using the gravimetric method. Fats and oils were determined using the Soxhlet extraction method. All the remaining parameters were analyzed using Hanna multiparameter photometer (HI83399) and associated reagents. Analysis was carried out according to Standard analytical methods

prescribed by Standard Methods for Examination of Water and Wastewater [17]. All analysis was performed in triplicates and the mean value taken.

#### **3.4 Assessment of processing practices and wastewater management**

The processing practices for palm oil production and wastewater management practices employed by the processing mills were obtained through the interviews and structured observation. Moreover, reasons for the wastewater management practices at the processing mills were ascertained through the interviews.
