Analysis of Physicochemical Parameters in Wastewater and Heavy Metals in Soils of Flower Farms in Ethiopia
Abstract
Floriculture is a young and fast-growing industry in Ethiopia. The sector has created employment opportunity and contributed to our country’seconomic development. But it is blamed for causing environmental pollution. Therefore, the aim of this study is to determine the concentration of pollutants in wastewater and soils of flower farms located in Ethiopia which were selected using purposive sampling. Wastewater and soil samples required for the determination of physico-chemical parameters and heavy metal concentrations were collected from the flower farms from April 1 to May 25, 2019. Physicochemical parameters including pH, electrical conductivity, total dissolved solids, phosphate, sulfate and chemical oxygen demand in wastewater, and concentrations of lead, cobalt, and zinc in soil were determined. Accordingly, the pH values of the four flower farms (Farm 1, Farm 2, Farm 4 and Farm 5) were slightly acidic and below minimum pH value (6) allowed for wastewater effluent set by Ethiopian Environmental Protection Authority. Electrical conductivity at all farms, total dissolved solid at Farm 4, chemical oxygen demand at Farm 3, and 4, sulphate at Farm 4, and phosphate at Farm 2 and 4 were above the provisional standard set by EPA. This study revealed that wastewater sample collected from Farm 4 doesn’tcomply with EPA standard in all study parameters. While, the mean concentrations of cobalt and zinc of soil samples varied from 2.8 to 46.6 mg/kg and 54.4 to 111.1 mg/kg, respectively. Conclusively, the wastewater quality discharged from flower farms is not at a level it cannot cause harmful effect. Therefore, there is a need to ensure that wastewater is properly treated before discharged into the environment. Also, the authors recommend that further holistic investigation should be carried out on socio-economic and soil pollution of the floriculture industry in Ethiopia.
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Introduction
Floriculture is a discipline of horticulture concerned with the cultivation of flowering and ornamental plants for gardens and for floristry, comprising the floral industry. It can also be defined as “The segment of horticulture concerned with commercial production, marketing, and sale of bedding plants, cut flowers, potted flowering plants, foliage plants, flower arrangements, and noncommercial home gardening” (Getu, 2009; Tilahun, 2013).
Floriculture is a young and fast-growing industry in Ethiopia. Since the industry is export-oriented, it serves to generate foreign exchange. According to Arefaynie ( 2009), the major factors that have contributed to the development of horticulture industry in Ethiopia include suitable climate, altitude, and availability of land, low labor costs and other favorable conditions. In 2002, there were only five floriculture farms in the country; however, by 2008, this number rose to more thana hundred (EHPEA, 2014)
The study conducted by Kassa (2017) stated that Ethiopian floriculture industries currently produce several flower species, including roses, gypsophila, hypericum, limonium, carnations, and chrysanthemum. Currently, Ethiopia is benefiting from this development through creating employment opportunity for unemployed citizens. In addition, the floriculture industry has given the country’sexport sector an alternative export commodity to the traditional predominant export of coffee. However, there are a number of challenges that must be resolved to continue the development of the sector with the present rapid pace. Among the challenges is high consumption of different chemicals by the sector which can damage the environment through its discharge. According to Tamiru (2007), the production of flowers uses more than 300 chemicals such as pesticides and growth regulators, which can kill useful organisms in the soil and disturb the biodiversity surrounding the flower farms. It is known that soil pollution can lead to water pollution if toxic chemicals leach into groundwater, or if contaminated runoff reaches streams, lakes, or oceans (Bolo and Brachet, 2010; FAO, 2017). Phosphorus fertilizers are among the sources of heavy metal inputs; and superphosphate fertilizers contain, in addition to nutrient elements, trace metal impurities like cadmium (Cd) and lead (Pb). Malidareh and his colloeges (2014) showed that fertilizers might contain heavy metals that can cause serious problems in water and soil. Therefore, the objective of this study was to assess the status of environmental pollutants in five flower farms located in Central Ethiopia by analyzing physico-chemical parameters in wastewater and selected heavy metals in soils.
Conclusion
This study revealed that wastewater discharged from most study flower farms has contaminant concentration not in accordance with permissible level. Among the physicochemical parameters investigated: pH (for Farm 1, 2, 4, and 5), electrical conductivity (for Farm 1 to 5), chemical oxygen demand (for Farm 3 and 4), and phosphate (for Farm 4) not comply with the levels recommended for wastewater discharge set by EPA. Conclusively, the wastewater quality discharged from flower farms is not at a level it cannot cause harmful effect on the environment.
It is inevitable that some amount of pesticides from flower farms can reach our primary concerni.e. human beings and cause undesired impacts. Hence, the flower farms should shift to organic farming which relies on natural methods to control pests and diseases such as crop rotations, composting, encouraging the natural predators of common pests, and developing healthy flowers that have a natural resistance to pests and diseases, so that the related risk can be reduced. And also there is a need to ensure that wastewater is properly treated before discharge into the environment. Adding to this, the author’srecommend that further holistic investigation should be carried out on socio-economic and soil pollution status of the floriculture industry in Ethiopia.
