Indigenous plants for informal greywater treatment and reuse by some households in Ghana

Poor greywater management is one of Ghana ’ s sanitation nightmares due to longstanding neglect. This study looks at local practices of informal phytoremediation, and identi ﬁ es commonly used plants and bene ﬁ ts. Our study collected data from 451 surveyed houses in nine communities within three regions, using structured questionnaires and extensive ﬁ eld observations. Greywater (kitchen, bathroom and laundry) is mainly disposed of into the open (46 – 66%), with few (4 – 24%) using septic tanks and soakaway systems. The majority of respondents (84%) perceived plants as agents of treatment and most could list 1 – 2 bene ﬁ cial functions of the plants. A total of 1,259 plant groups were identi ﬁ ed which belonged to 36 different plant species. The top ﬁ ve indigenous plants used are sugarcane, banana/plantain, taro, sweet/wild basil, and dandelion. The major plant bene ﬁ ts identi ﬁ ed were food (84% of respondents) and medicine (62% of respondents). Statistically, no association was identi ﬁ ed between the numbers of plants grown and their perceived plant roles ( χ 2 ¼ 6.022, p ¼ 0.304), with the exception of an association between plant numbers and bene ﬁ ts ( χ 2 ¼ 161.94, p < 0.001). There is demand for improving local practices of using plants in greywater treatment and reuse, since native plants also come with other bene ﬁ ts.

Ghana due to contaminants. At least 280 organic micropollutants can be detected in greywater (Etchepare & van der Hoek ) and such contaminants include pharmaceutical and personal care products, pesticides, agrochemicals, surfactants, artificial sweeteners, pathogens, etc., which are difficult to handle (Boyjoo et al. ; Luo et al. ; Cardenas et al. ).
A recent publication on greywater characteristics in Ghana shows that greywater discharge into water bodies is likely to adversely affect their natural biological processes (Dwumfour-Asare et al. ). However there is no comprehensive strategic policy or management framework for greywater treatment and disposal in Ghana, although some regulations such as the national building regulations, and some local byelaws, touch briefly upon specific disposals in certain contexts (GoG ; GWMA ). Overall, existing management practices are highly unsatisfactory, often using unimproved methods, and in some cases, no greywater treatment at all. This disregard for greywater management is worsened by ignoring technologies that are often technically sophisticated, expensive, and usually inapplicable to low-income settings (Cardenas et al. ). The prevailing situation in Ghana justifies the need to lobby for policy intervention and con-

Study area description
Peri-urban areas, also called transition or interaction zones, adjoin urban areas, but are outside the formal urban boundaries and urban jurisdictions (Appiah-Effah   Handcock & Gile ). The sampling approach was also supported by asking around the vicinities for potential respondents, and/or link-tracers, in places where a respondent is not able to identify the next potential respondent.
The principal focus of the study was on the use of indigenous plants/vegetation in greywater disposal rather than the study communities or sites. All data processing and analysis

Profile of study households
The gender distribution of respondents is 66% females and 34% males (N ¼ 451). The survey specifically targeted female respondents because they are the ones largely responsible for sanitation issues in the home (Dwumfour-Asare et al. ). The average age of respondents was 43 years with 95% confidence interval (CI) 41.5-44 years (Table 1). The majority of the respondents were married 67% (n ¼ 301) whilst the rest (33%) were single, separated, divorced or widowed.
The majority of the respondents were self-employed (56%, N ¼ 451), followed by unemployed 25% (n ¼ 111) and the balance in paid employment (17%) or retired

Indigenous plants use in greywater disposal
The main greywater source for watering indigenous plants is bath water. This was well supported by the visual evidence The main plant functions that were identified by the respondents are listed in Table 3.
The most familiar plant function was 'treat greywater', followed by 'remove odour' and the rest in the order presented in      (Table 6). All the plants identified in the survey are locally available, and households intentionally planted almost all of them. Very few were self-sowing volunteer species that were nevertheless allowed to grow with the planted species.
The top ten plants identified by the study are: sugarcane, banana/plantain, taro, sweet/wild basil, dandelion, tobacco, leaf of life, cocoyam/tannia, aloe vera, coconut/African oil palm, lemon grass, pepper/tomato/okro, and mango/ orange ( Figure 3). All the plants identified are used in Ghanaian communities for food and medicinal purposes, including the top ten plants listed. Our findings follow these plants uses, because the respondents reported that the main benefits they derive from indigenous plants were food (84%, n ¼ 379), and medicine (62%, n ¼ 281) (Figure 4).
Thus, the results support the earlier statistical assertions that the plants are primarily grown for agronomic uses, particularly for food and medicine. This does not contradict the respondents' perception and understanding that plants help treat the greywater. However, it emphasises people's overarching interest in the basic advantages of water and nutrients supplied from greywater to plants.
Apart from one house, all 450 households were motivated by one or more specific plants benefits, such as providing food, medicine, shade/shelter, aesthetics, fodder and hedge/fence (Figure 4). In a later part of the data collection, a limited number of respondents (50) were asked which of the plant parts were used for food and medicine.
A small number were not using any plant parts (12%, n ¼ 6) whilst a sizable majority depended on the leaves (66%,

Potential for indigenous plants use in greywater treatment
The findings suggest that more can be done with the lesser known indigenous plants in the areas of green technologies.
Exploring the plants with phytoremediation designs such as  warranted, and several native plants could be explored for use in simple and also more sophisticated technologies.
As part of the initiative to improve local disposal practices, it is recommended that a clear and robust design and installation standard and guidelines should be developed, communicated and enforced.