Assessment of Capsicum annuum L. Grown in Controlled and Semi-Controlled Environments Irrigated with Greywater Treated by Floating Wetland Systems

Vincent C. Uzomah,Suhad A. A. A. N. Almuktar,Miklas Scholz,Suhail N. Abed

doi:10.3390/agronomy11091817

Abstract

Accumulation of trace elements, including heavy metals, were evaluated in soil and fruits of chilli plants (Capsicum annuum L.) grown under both laboratory-controlled and semi-controlled greenhouse location conditions. Chilli plant biomass growth in different development stages and fruit productivity were evaluated and compared with each other for the impact of growth boundary conditions and water quality effects. Treated synthetic greywaters by different operational design set-ups of floating treatment wetland systems were recycled for watering chillies in both locations. Effluents of each individual group of treatment set-up systems were labelled to feed sets of three replicates of chilli plants in both locations. Results revealed that the treated synthetic greywater (SGW) complied with thresholds for irrigation water, except for high concentrations (HC) of phosphates, total suspended soils, and some trace elements, such as cadmium. Chilli plants grew in both locations with different growth patterns in each development stage. First blooming and high counts of flowers were observed in the laboratory. Higher fruit production was noted for greenhouse plants: 2266 chilli fruits with a total weight of 16.824 kg with an expected market value of GBP 176.22 compared to 858 chilli fruits from the laboratory with a weight of 3.869 kg and an estimated price of GBP 17.61. However, trace element concentrations were detected in chilli fruits with the ranking order of occurrence as: Mg > Ca > Na > Fe > Zn > Al > Mn > Cu > Cd > Cr > Ni > B. The highest concentrations of accumulated Cd (3.82 mg/kg), Cu (0.56 mg/kg), and Na (0.56 mg/kg) were recorded in chilli fruits from the laboratory, while greater accumulations of Ca, Cd, Cu, Mn, and Ni with concentrations of 4.73, 1.30, 0.20, 0.21, and 0.24 mg/kg, respectively, were linked to fruits from the greenhouse. Trace elements in chilli plant soils followed the trend: Mg > Fe > Al > Cr > Mn > Cd > Cu > B. The accumulated concentrations in either chilli fruits or the soil were above the maximum permissible thresholds, indicating the need for water quality improvements.

Highlights

Some of the challenges facing water resource management include climate change phenomena, such as droughts linked to global warming
The effluents from different set-up designs of floating treatment wetlands (FTW) (Table 2) were recycled to irrigate potted chilli plants grown in the laboratory and greenhouse
Greywater and wastewater treatment systems, such as all types of constructed wetlands, can provide effluents to be recycled for irrigation

Summary

Introduction

Some of the challenges facing water resource management include climate change phenomena, such as droughts linked to global warming. Anthropogenic activities have negatively affected natural resources, such as freshwater, in terms of its quality compared to international standards for safe usage [1,2]. Severe climate and environmental challenges have been predicted for Australia, the Middle East, North Africa, and the southern. USA [3,4]. The world population in 2050 might hit 9.7 billion; this number could reach. 11.0 billion by 2100 [5]. The population growth rate increase might lead to mass migration. More than 67% of the world population could face water shortages by

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