Abstract
Excessive use of detergents in wide industrial processes results in unwanted surfactant pollution. Among them, sodium dodecyl sulphate (SDS) has well-known history to be used in pharmaceutical and industrial applications. However, if discharged without treatment, it can cause toxic effects on living organisms especially to the aquatic life. Floating treatment wetlands (FTWs) could be a cost-effective and eco-friendly options for the treatment of wastewater containing SDS. In this study, FTWs mesocosms were established in the presence of hydrocarbons-degrading bacteria. Two plant species (Brachiaria mutica and Leptochloa fusca) were vegetated and a consortium of bacteria (Acinetobacter sp. strain BRSI56, Acinetobacter junii strain TYRH47, and Acinetobacter sp. strain CYRH21) was applied to enhance degradation in a short-time. Results illustrated that FTWs vegetated with both plants successfully removed SDS from water, however, bacterial augmentation further enhanced the removal efficiency. Maximum reduction in SDS concentration (97.5%), chemical oxygen demand (92.0%), biological oxygen demand (94.2%), and turbidity (99.4%) was observed in the water having FTWs vegetated with B. mutica and inoculated with the bacteria. The inoculated bacteria showed more survival in the roots and shoots of B. mutica as compared to L. fusca. This study concludes that FTWs have the potential for the removal of SDS from contaminated water and their remediation efficiency can be enhanced by bacterial augmentation.
Highlights
The consumption of detergents is increasing due to industrialization and urbanization, which results in the discharge of a higher concentration of these pollutants in the environment
Performance of B. mutica was better than L. fusca which could be due to the better adaptability of B. mutica in this kind of wastewater
A significantly better reduction in sodium dodecyl sulphate (SDS), COD, and BOD concentration (90–97.5%) was observed in the Floating treatment wetlands (FTWs) having both vegetation and bacterial inoculation (T2 and T4) than in the FTWs having only vegetation (T1 and T3) or bacterial inoculation (T5). This could be due to the effective plant-microbe interplay in the FTWs: (1) inoculated bacteria were previously isolated from the shoot and root interior of plants so they could have already developed mechanisms of proliferation in the plant rhizo- and endosphere that allow the bacteria have helped degrade the SDS and supported the health of host plant in a synergistic manner, and (2) the bacteria possessed genes involved in pollutant degradation and plant growth promoting activities, i.e., 1-aminocyclopropane-1-carboxylate (ACC) deaminase, siderophores production, phosphorus solubilization [54,55,56,57]
Summary
The consumption of detergents is increasing due to industrialization and urbanization, which results in the discharge of a higher concentration of these pollutants in the environment. Detergents are synthetic organic compounds that are used extensively in different cleansing activities such as car washing facilities, laundries, household as well as in many industries such as cosmetics, textile, paper, etc. A typical detergent contains surfactants (10 to 20%), bleach (7%), phosphate builders (50%), and additives (23–33%). Surfactants are the components that are responsible for the cleaning action of detergents [6,7]. Surfactant molecules are composed of a polar head group which may either be charged or uncharged and a non-polar hydrocarbon tail [8,9,10]
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