Performance of a Pilot-Scale Constructed Wetland and Medium-Term Effects of Treated Wastewater Irrigation of Arundo donax L. on Soil and Plant Parameters

Abstract

On marginal lands in the Mediterranean basin, giant reed (Arundo donax L.) represents one of the most interesting perennial crops due to high levels of biomass production. Considering periodic water shortage during the summer months in this area, the reuse of treated wastewater (TWW) would seem to be a good opportunity for the growth of the species. The aim of this study was to assess the medium-term effects of irrigation using freshwater (FW) and TWW on soil characteristics and growth in giant reed plants. TWW was obtained from a pilot-scale horizontal subsurface flow constructed wetland system (HSSF CWs) with a total surface area of 100 m2. A split-plot design for a two-factor experiment was used with three replications. Medium-term TWW irrigation increased organic matter and plant nutrients in the soil; however, pH was not affected. Plants irrigated with TWW showed greater growth (+10.49% in height, +12.75% in stem diameter, +11.51% in above-ground biomass) than those irrigated with FW. The higher heating value of crop residues ranged between 16.83 (FW-irrigated plants) and 17.00 MJ kg−1 (TWW-irrigated plants). Results show that HSSF CWs produces TWW, which can be an alternative source of water for growing giant reed with high biomass performance.

Treated municipal wastewater as option to the use of fresh water for the cultivation of valuable pastoral species Buffel grass (Cenchrus ciliaris L.)

“…Accumulation of OM in soil through irrigation with wastewater can result in an improvement of soil chemical and physical properties, with consequent positive effects on environment and plants. This work evidenced a positive effect of TWW on soil, showing a growing increase in soil nutrients, increasing the time of watering, in agreement with previous studies of Heidarpour et al (2007) and Bedbabis et al (2010) indicating that after 4 years of irrigation, TWW decreased the pH and increased OM and ions amounts (Licata et al, 2021); the results were perfectly in agreement also with previously findings of Bredai et al (1996) and with a recent research of Mojid et al (2019), evidencing as the degree of changes in soil properties is anyway a function dependent from soil and wastewater type. Wastewaters (municipal and not) can be utilized for ameliorating physicochemical soil properties and the strong relationship that exists between wastewater and soil organic carbon can be useful to design and manage soil irrigation with wastewater.…”

“…Seasonal changes of diverse gas exchange parameters including A n , g s and T r are shown in (Licata et al, 2021); the results were perfectly in agreement also with previously findings of Bredai et al (1996) and with a recent research of Mojid et al (2019), evidencing as the degree of changes in soil properties is anyway a function dependent from soil and wastewater type. Wastewaters (municipal and not) can be utilized for ameliorating physicochemical soil properties and the strong relationship that exists between wastewater and soil organic carbon can be useful to design and manage soil irrigation with wastewater.…”