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

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.

Knowledge Atlas on the Relationship between Water Management and Constructed Wetlands—A Bibliometric Analysis Based on CiteSpace

“…Sustainability 2022, 14, x FOR PEER REVIEW 6 of 30 maintaining a certain number of publications in 2006, including a study on the efficiency of CW water at removing pollutants from agricultural wastewater over a seven-year period [40], as well as the rates of agricultural and domestic wastewater purification by an integrated constructed wetland simulated by the multiple regression model, principal component analysis, redundancy analysis, and a self-organizing map model. Moreover, the study investigates the recycling of grey water treated by CWs for crop irrigation, and the high temperature to improve the quality of the water purification in CWs [41,42]. Robert Kroeger's research focuses on a pollutant breakdown by plant [43][44][45], Rory Harrington's research focuses on integrated CW research [40,46], and Sarah A White's research focuses on floating-wetland purification [47].…”

Biomass Production and Metal Remediation by Salix alba L. and Salix viminalis L. Irrigated with Greywater Treated by Floating Wetlands

“…The observed TSS concentrations of all the treated LC-SGW were lower than 100 mg/L. Elevated TSS values in this case can be attributed to substrate composition distortion, reduction in substrate porosity, and substrate clogging [30]. Furthermore, electric conductivity (EC) serves as an indicator of water salinity, and it is advisable for EC to remain below the maximum limit of 3000 µS/cm as stated by both the FAO [14] and the WHO [15], since high salinity and EC in agricultural soil and water negatively effect soil structure, water and air exchange in the soil, as well as crop biomass productivity [25].…”

“…In terms of physical properties, the compost substrate had a low bulk density and a high organic content proportion, providing a substrate with a high total porosity, stable substrate structure, good hydraulic conductivity, as well as a high water-retention time. A good compost water-holding potential and water-retention capacity are linked to high substrate porosity [30].…”

“…However, the authors have not found any reported toxicity cases linked to human health or the environment due to the accumulation of Al in substrates and plant tissues. For high concentrations of Ca ions in a substrate, the mobility of Al is constrained within plants due to a negative correlation between Al ion exchange and substrate pH [30,50]. Furthermore, traces of B were detected in a few substrate samples (Table 3 and Figure 5b).…”