Abstract
BackgroundBioremediation is the use of biological interventions for mitigation of the noxious effects caused by pollutants in the environment including wastewater. It is very useful approach for a variety of applications in the area of environmental protection. It has become an attractive alternative to the conventional cleanup technologies that employ plants and their associated microorganisms to remove, contain, or render harmless environmental contaminants.MethodsThree parallel hydroponic treatment systems (each 2 m long × 0.75 m wide × 0.65 m deep) and one control unit were filled with brewery wastewater to an effective depth of 0.5 m. Two sets of floating polystyrene platform were used for each treatment unit to support vetiver tillers for conducting bioremediation study. The wastewater was fed to the hydroponic treatment units at hydraulic loading rate of 10 cm d−1 and hydraulic residence time of 5 days. Influent and effluent samples were collected once a month for 7 months, and analyzed to determine the various parameters relating to the water quality including plant growth and nutrient analyses.ResultsVetiver grass grew and established with well-developed root and shoots in the hydroponics under fluctuations of brewery wastewater loads and showed phytoremedial capacity to remove pollutants. Removal efficiencies for BOD5 and COD were significant (p < 0.05), up to 73% (748–1642 mg l−1 inlet), and up to 58% (835–2602 mg l−1 inlet), respectively. Significant removal efficiencies (p < 0.05) ranged from 26 to 46% (14–21 mg l−1 inlet) for TKN, 28–46% (13–19 mg l−1 inlet) for NH4+-N, 35–58% (4–11 mg l−1 inlet) for NO3−-N, and 42–63% (4–8 mg l−1 inlet) for PO4−3-P were recorded. Nutrient accumulation in the samples harvested were varied between 7.4 and 8.3 g N kg−1 dry weight and 6.4–7.5 g P kg−1 dry weight in the hydroponic treatment units during the study period.ConclusionsThis study has shown suitability of vetiver grass for organics and nutrient removal in the bioremediation of brewery wastewater using hydroponics technique in addition to production of valuable biomass. Bioremediation using hydroponics is green and environmentally sustainable approach that offers promising alternative for wastewater treatment in developing countries including Ethiopia.
Highlights
Bioremediation is the use of biological interventions for mitigation of the noxious effects caused by pollutants in the environment including wastewater
A pilot-scale hydroponic treatment system (HPT) consisting of a primary settling tank (1 m3), a feed tank (1.5 m3), three hydroponic treatment units configured in parallel, and a common effluent holding tank were constructed from concrete
It can be noted that the trends and variability of the values of the physicochemical parameters revealed the fluctuation of brewery wastewater composition
Summary
Bioremediation is the use of biological interventions for mitigation of the noxious effects caused by pollutants in the environment including wastewater. It is very useful approach for a variety of applications in the area of environmental protection. Due to rapid growth of beer consumption in Ethiopia (24% per year) (Nebyou 2011) and the discharge of 70% of the water used by the brewing industry as effluent, the projected expansion of the brewery sector will significantly increase the pressure on the water supply (Olajire 2012; Joshua and Kehinde 2014). In spite of significant technological improvements, water consumption, wastewater, solid waste, and by-products and emissions to air remain major environmental challenges for the brewing industry (Fillaudeau et al 2006; Pettigrew et al 2015; Alayu and Yirgu 2017)
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