*4.4.2 Reasons for current wastewater management practices in Central Region, Ghana*

The reasons ascribed by the processing mills for disposal of untreated wastewater in the natural environment are presented in **Figure 7**.

All the operators of the processing mills are aware of the legal requirement to treat the wastewater generated by their activities. However, majority (48%) of the operators blamed the absence of treatment system on their limited technical capacity on wastewater management. Others (36%) do not have the financial resources to construct and manage a treatment facility. Finally, few processing mills took advantage of limited enforcement of environmental regulations by the relevant Government Agency (Ghana Environmental Protection Agency) to dispose of their wastewater without treatment. Comparatively, a study conducted by Gyamfi [24] revealed that 70% of respondents from small-scale mills in Ashanti, Eastern, Central and Western

#### **Figure 6.**

*Wastewater disposal practices at small-scale palm oil processing mills in the Central Region of Ghana (source: Authors).*

#### **Figure 7.**

*Reasons for absence of wastewater treatment facilities at small-scale processing mills in the Central Region of Ghana. (source: Authors).*

regions of Ghana were either not aware or did not know how to comply with national environmental laws and regulations. The economic activities (in law or practice) of small-scale mills are not or insufficiently covered by formal arrangements including registration and regulation [23].

#### *4.4.3 Potential environmental impacts of current wastewater management practices*

The concentrations of most of the parameters were over 2-order of magnitude higher than the limits set by Ghana Standards Authority (see **Table 4**). Palm-oil extraction wastewater disposed on land could be washed into surface water bodies by runoff. When washed into water bodies, the high organic content of the wastewater could deplete the oxygen content of the receiving water bodies [33, 34] and affect the life of their aquatic organisms [35]. Using a per capita BOD loading of 54 gBOD/day [36], the population equivalent (PE) of the small-scale industry is about 200 inhabitants. Excessive fats and oils may form scum [37] on the surface of waterbodies further depriving the water body of dissolved oxygen.

Moreover, the untreated wastewater pollutes the air through odor production as reported by Ahmad and Ghufran [38] and Loh, Lai [39]. Aside the odor, the degradation of the wastewater could generate biogas with over 60% methane content [39, 40]. Methane gas is considered one of the potent greenhouse gases and contributes 25 times to global warming compared to CO2 [41]. The current practice of disposing raw wastewater into the natural environment by small-scale processing mills is negatively affecting the environment.

#### **4.5 Other palm-oil extraction waste products and their management in Ghana**

#### *4.5.1 Solid waste*

The categories of solid waste generated at the processing mills are empty fruit bunches (EFB), palm pressed fiber, palm kernel (PK), and ash from boiler furnaces. The high moisture content of EFBs prevents their immediate use as solid fuel. At most of the small-scale mills, the EFB are heaped and left to undergo decomposition. Some small-scale mills dry and use EFBs and palm press fibers as solid fuel for boiling the

palm fruits as reported also by Gyamfi [24]. At the small-scale mills, palm kernels are mostly sold to palm kernel processors which are used to produce palm kernel oils.

#### *4.5.2 Smoke*

Smoke is generated from the boiling activities or open burning of EFBs. The smoke hangs over the mills causing discomfort to mill workers as noted by MASDAR [11]. The community members who reside close to the mills are also affected by the smoke. The smoke is mostly generated within the breathing zone of the mill workers which could potentially affect the health of the mill workers. In the study area, small-scale mills do not have in place measures and appropriate technology to control or manage smoke produced from their activities. In Elele, Nigeria, Ohimain and Izah [42] measured elevated concentrations of carbon monoxide, sulfur dioxide, nitrogen dioxide, volatile organic compounds, and suspended particulate matter at small-scale palm oil processing mills with most of the parameters above the Nigerian Ambient Air Quality standards. Diesel exhaust fumes from digesters contribute significantly to combustion-derived particulate matter air pollution [42].

#### *4.5.3 Noise pollution*

Mechanical digesters used by the mills produce noise. There is no technology in place to control the noise generated by the machinery used for processing. Application of noise-reduction technologies at small-scale processing mills in other study areas has not been reported in scientific literature. Moreover, the level of noise produced by the mechanical equipment used by small-scale mills in Ghana has not been investigated. In Nigeria, noise levels generated at small-scale mills were within permissible limits of 90 dB [43]. At the large mills in Ghana (such as Twifo Oil Palm Plantation), noise is minimized by installation of silencers to exhaust and rubberlining ducts and cyclones within the plant controlling noise levels.

#### *4.5.4 Odor nuisance*

The odor at the small-scale processing mills studied is associated with rotten fruits, decomposing EFB and POME. Unpleasant odor pervades the mills and downwind of the POME and EFB disposal sites.
