Performance of carbendazim removal using constructed wetlands for the Ethiopian floriculture industry

Abstract

Carbendazim is a pesticide commonly used in Ethiopian flower farms and has harmful effects on aquatic, invertebrate, and mammalian life. Previous studies have explored ways to remedy carbendazim toxicity; however, the use of constructed wetland (CW) systems for carbendazim removal from farm water runoff has not been explored in depth. The primary aim of this study was to investigate the efficacy of a CW system for carbendazim removal from wastewater runoff. A two-stage pilot CW was built and tested for its efficacy of carbendazim removal under saturated conditions and varying hydraulic loading rates. The influent was pumped into the first vertical-flow mesocosm. The drained water was then pumped into the second mesocosm. The collected effluent was tested for carbendazim removal. Carbendazim removal efficiencies up to 91.80% (with a hydraulic loading rate of 100 Ld−1 and influent carbendazim concentration of 10 μg L−1) were observed. Statistical analysis indicated that the removal of carbendazim was not correlated with the initial carbendazim concentration but was negatively correlated with the hydraulic loading rate used. Two pesticide removal mechanisms were briefly probed to determine their participation in carbendazim removal. Substrate sorption accounted for 18% of total carbendazim removal; furthermore, plant uptake also played an active role.

Unsaturated Vertical Flow Constructed Wetland for Chlorothalonil Remediation with Target Application in Ethiopian Floriculture Industry

“…The experimental setup used in a previous study was adopted and modified for use in this study [28]. The CW was constructed at the RAK Research and Innovation Center, Ras Al-Khaimah, UAE (latitude: 25.6685406; longitude: 55.7794520).…”

A Mechanistic Model for Simulation of Carbendazim and Chlorothalonil Transport through a Two-Stage Vertical Flow Constructed Wetland

“…The specific design of the CW followed was adapted from the previous experimental work in Wehbe et al (2022) and Wehbe et al (2023) [16,17]. Substrate water flow was described with the Richards equation, while the movement of pesticide was described with an advection-dispersion equation coupled with diverse processes, which are detailed in the later Section 2.3.…”

“…The list of simulation cases is as described in Table 3. The details of the experimental setup are described in Wehbe et al (2022) and Wehbe et al (2023) [16,17]. There were two distinct cases: (i) carbendazim was treated under the unsaturated condition (corresponding to Case 7), and (ii) a very high concentration of chlorothalonil was fed to the system under the unsaturated condition (corresponding to Case 14) in terms of different natures of experiments for the treatment of each compound.…”

“…There are various types of CWs that have been studied over the years for the treatment of agricultural runoffs [12,13]. The use of vertical flow constructed wetlands for pesticide treatment has been studied recently [14][15][16][17], which has shown great promise towards efficient removal of pesticides. A lot of these studies usually describe the removal efficiency of the pesticides from wastewater; however, very few manage to conduct a more detailed study of pesticide concentration dynamics as the wastewater passes through the substrate bed [18].…”

Challenges and opportunities existing in the floriculture industry in Africa: knowledge and future research prospects

“…Along with other floriculture-producing countries in Africa, Ethiopia has no strong and functional system or structure to control the impacts of floriculture farms (Gelaye, 2023). This is the case with carbendazim, a pesticide commonly used on Ethiopian flower farms, which has harmful effects on aquatic life, invertebrates, and mammals (Wehbe et al, 2022). Scientists could also consider the advantages of focusing on plant fungal pathogens (Shuping and Eloff, 2017).…”