Contaminations of Soil and Two Capsicum annuum Generations Irrigated by Reused Urban Wastewater Treated by Different Reed Beds

Abstract

Background: In order to save potable water, this study aims to evaluate the contamination of soil and Capsicum annuum L. (chilli) watered with urban wastewater (sewage) pre-treated by various wetland systems. Methods: The appropriateness of wetland outflow for irrigation when applying reused wastewater with high contamination of minerals and pathogens was assessed. The impact of wastewaters pre-treated by various wetlands on soil and harvest was tested in terms of mineral and biological contamination risk. Results: The wetlands met the standards for irrigation water for most water quality variables. However, the thresholds for key water quality parameters were significantly (p < 0.05) exceeded. The highest values for total coliforms, ammonium-nitrogen, phosphorus and potassium were 157,072 CFU/100 mL, 8.5 mg/L, 5.0 mg/L, and 7.0 mg/L, respectively. The harvest was moderately polluted only by zinc according to vegetable quality standards (threshold of 50 mg/kg). Zinc concentrations for Filters 2, 4, 6, 7 and 8 were 35.8, 60.6, 65.1, 65.5 and 53.2 mg/kg, respectively. No bacterial contamination was detected. Conclusions: Treatment of domestic wastewater applying constructed wetlands and subsequent recycling of the treated wastewater for irrigation of crops is a good substitute to the traditional application of drinking water for irrigation purposes.

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

“…A good compost water holding potential and water retention capacity is linked to high soil porosity. In addition, the authors reduced water evaporation and increased the moisture content of the compost by covering the top compost layer with small-chipped bark [3].…”

“…Crop productivity, plant biomass, soil structure, and nutritious content could be positively impacted with an increase in the organic matter content. In contrast, a too high organic loading rate could clog the soil causing an anaerobic condition in the root-zone, thereby depleting nitrogen through denitrification in organic biodegradation processes [3]. Therefore, the low organic matter content in greywater recycling could address this serious concerns compared to recycling of blackwater or mixed-resource wastewater for irrigation [21].…”

“…Overall yields of chillies irrigated by treated greywater were low, indicating challenges with elevated salinity [76]. However, irrigation with greywater had no negative effect on the plant dry biomass, number of leaves, and water demand [3]. Water stress might cause low fruit productivity in terms of weight, diameter, and length [77].…”

“…Nutrients provided to the chilli plants by treated greywater and compost soil could be considered efficient for good harvesting. However, plant water consumption is related to the environmental weather conditions and growth stage, it is not strongly linked to the fruit productivity [3]. It was indicated that there was no significant difference in plant water consumption when comparing the laboratory to greenhouse plants [82].…”

“…Anthropogenic activities have Agronomy 2021, 11, 1817 2 of 32 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].…”