**4. Results and discussion**

#### **4.1 Palm oil production processes in Ghana**

The production processes used in the study area generally reflect what is employed in other parts of Ghana. The processing of fresh palm fruits into crude palm oil involves receipt of fresh fruit bunches, splitting, storage, stripping, fermentation, boiling, digestion/pressing and clarification. The only mechanized operations are digestion and/or pressing of boiled fruits as noted by other authors [15, 18]. However, fermentation of fresh or boiled fruits is an optional activity which is used depending on the expected grade (food or soap) of the crude palm oil produced. **Table 2** describes the production processes employed by the small-scale processing mills in the Central Region of Ghana. The corresponding process flow diagram is shown in **Figure 5**.

#### **4.2 Environmental regulations for palm oil processing mills in Ghana**

#### *4.2.1 Environmental permitting*

Palm oil processing mills (small-, medium- and large-scale) are required under Regulation 1 of the Ghana Environmental Assessment Regulations, 1999 (LI 1652) to register with and obtain environmental permit from the Ghana Environmental Protection Agency (EPA) prior to the commencement of the undertaking. In addition, existing undertakings, where EPA considers to have or is likely to have adverse effect on the environment or public health, are required to register with and obtain environmental permit in respect of the undertaking. Similarly, the Environmental Protection Agency Act, 1994 (Act 490) authorizes the EPA "to issue environmental permits and pollution abatement notices for controlling the volume, types, constituents and effects of waste discharges, emissions, deposits or any other source of pollutants and of substances which are hazardous or potentially dangerous to the quality of the environment or a segment of the environment."

The Ghana EPA is therefore legally mandated to regulate and enforce all environmental laws and regulations. But, the small-scale processing mills belong to the informal sector where compliance to legal requirements has been noted to be relatively weak [22, 23]. The economic activities (in law and practice) of small-scale mills are not or insufficiently covered by formal arrangements including registration and regulation [23]. This is confirmed by Gyamfi [24] that 70% of respondents from small-scale mills in Ashanti, Eastern, Central and Western regions of Ghana were

#### **Table 2.**

*Description of small-scale palm oil production processes in Ghana.*

*Small-Scale Palm Oil Production in Ghana: Practices, Environmental Problems and Potential… DOI: http://dx.doi.org/10.5772/intechopen.106174*

#### **Figure 5.**

*Process flow diagram for palm oil processing at small-scale level. Source: Authors.*

either not aware of or did not know how to comply with national environmental laws and regulations.

#### *4.2.2 Effluent standards for palm oil mill industry in Ghana*

Wastewater produced by the palm oil processing mills are required to be treated to meet the Ghana Environmental Protection – Requirements for Effluent Discharge (GS 1212:2019) Standard [25] promulgated by the Ghana Standards Authority. The Standard specifies the requirements for sector specific effluent quality and gives guidelines for discharge of effluents into the environment. **Table 3** shows the effluent discharge standard for oil and fat processing which includes the palm oil industry.


**Abstract**

Spectral domain optical coherence tomography (SD-OCT) is a common useful noninvasive imaging instrument which is used for the diagnosis and follow-up of macular disorders. The clinical findings by OCT in these pathologies are well known. Currently, due to the development of this technology and its wide use, new OCT findings have been reported in the literature. The aim of this chapter is to describe new pathological or abnormal signs and findings in SD-OCT, including hyperreflective spots or dots, flyer saucer sign, outer retinal tubulations, dipping sign, focal choroidal excavation, outer retina-choroid complex splitting, foveal pseudocyst, brush border pattern, dome-shaped macula, pearl necklace sign, choroidal macrovessel, cystoid foveal degeneration, and disorganization of the retinal inner layers (DRIL).

**Keywords:** hyperreflective spots, perifoveal cupping, flyer saucer sign, tubulations, dipping sign, outer retina-choroid complex splitting, foveal pseudocyst, brush border pattern, dome-shaped macula, pearl necklace sign, macrovessel, disorganization of the retinal inner layers


**5.3. Network structure of low dielectric materials**

In defining the different types of network structure materials for low dielectric constant applications in microelectronics, two classifications may exist. One is organic networks based on elemental carbon including amorphous carbon (diamond-like-carbon(DLC)) [35,36] and interpenetrating polymer network (IPN). The other is inorganic networks based on silicon oxide bonds such as amorphous SiO2 and mesoporous crystalline silicon oxide.

Low Dielectric Materials for Microelectronics 71

aromatic starting compounds, which contain ortho-bisethinyl or -phenylethinyl groups [38]. The materials exhibit k values on the order of 2.6-2.7, with decomposition temperatures in excess of 500°C, no softening up to 490°C, good gap fill properties down to below 0.1 um, a maximum water uptake of 0.25%, and a coefficient of thermal expansion 4s

Benzocyclobutene (BCB) resins were developed by Dow in the 1980's [39], with a siliconcontaining derivative for microelectronics applications, and are commercially available under the name 'Cyclotene'. BCB resins with imide structures can be extremely tough, and the dielectric constant of cured films from this monomer is 2.6-2.7, with thermal stability up

Inorganic networks mainly consist of ceramics or amorphous silica. In various materials for microelectronics, the silicon oxides play a major role due to its low polarizability, superior thermal and mechanical properties. In addition, tunable microspores can be made to reduce the dielectric constant through control of microstructure under special

Microporous zeolite thin films were first investigated by Yan and co-workers. [43] These films offer good thermal stability (i.e. no pore collapse or unidirectional shrinkage) and inter-particle mechanical strength. They can be prepared via a simple spin-on method [43,44] or by in situ growth. [44,45] With simple spin-on methods a dispersion of small zeolite particles are prepared and cast onto a surface. The porosity originates from the interparticle porosity within the zeolite nanoparticles and the intraparticle porosity owing to the packing of the near-spherical nanoparticles in thin film

Some of the most promising materials for dielectric materials are poly(silsesquioxanes). Most common are polymethylsilsesquioxane (MSQ), e.g. Accuspin T-18 from Allied Signal [46], or poly(hydridosiLsesquioxane) (HSQ), e.g. FOx from Dow Corning [47]. Synthesis of these silsesquioxanes(MSQ and HSQ) have traditionally been through the sol-gel method, as its utility in being able to obtain highly cross-linked structures through acidic and or basic conditions has been well documented [48,49,50]. Dielectric constant values of around 2.6 can be achieved for HSQ and MSQ. But while MSQ exhibits this dielectric constant after curing at temperatures up to 450°C, HSQ must be cured at temperatures lower than 210°C [51]. Curing of HSQ at temperatures of 250°C or above results in dielectric constant around 3 or even higher 32°[51,52]. Gap fill and planarization properties are also acceptable and because of their chemical structure, which is closely related to SiO2, polymethylsilsesquioxanes are

of 66 ppm/K.

conditions.

format.

*5.3.2. Inorganic network*

*<IP_ADDRESS>. Ordered Mesoporous Materials*

*<IP_ADDRESS>. Network polysilsesquioxane*

also compatible with existing lithographic procedures.

to 375oC and water adsorption of only 0.2% [40,42].

Intuitively, network structures have excellent thermal stabilities and mechanical properties, and chemical resistance, but have relatively high density which is a factor in elevated dielectric constants. Because of this, dielectric constant and mechanical properties should be carefully controlled and careful consideration of its crystalline structure, as crystalline structures tend to be easily polarized.