Evaluation of Bed Depth Reduction, Media Change, and Partial Saturation as Combined Strategies to Modify in Vertical Treatment Wetlands

Abstract

The aim of this work was to evaluate the performance of vertical subsurface flow treatment wetlands (VSSF TWs) for treating rural domestic wastewater when strategies such as bed depth reduction and media change are used in combination with bottom saturation. Two treatment wetland systems were implemented: normal (VF-N), with a bed depth of 1.0 m, and modified (VF-M), with a bed depth of 0.5 m and a bottom layer of natural zeolite. Schoenoplectus californicus was used as experimental plant. These two treatment systems were operated at a hydraulic loading rate of 120 mm/d in two phases. Phase I did not use bottom saturation, while Phase II involved a bottom saturation of the zeolite layer of the VF-M system. The results show that bed depth reduction did not have a significant effect (p > 0.05) in terms of organic matter, solids, and ammonium removal. Conversely, it had a significant influence (p < 0.05) on phosphate as well as a negative effect on pathogen removal. This influence could be explained by initial media capacity for phosphorus removal and filtration importance in the case of pathogens. Partial saturation only had a positive influence on total nitrogen removal. The addition of a bottom layer of natural zeolite showed no positive effect on nutrient removal. The plant showed adaptation and positive development in both VF-N and VF-M. The water balance showed that water loss was not influenced by bed depth reduction. Therefore, according to the previous results, a combination of the proposal modifications to VSSF TWs can be introduced for treating rural domestic wastewater.

Performance Comparison of Vertical Flow Treatment Wetlands Planted with the Ornamental Plant Zantedeschia aethiopica Operated under Arid and Mediterranean Climate Conditions

“…Regarding height, the control plant, Sc, showed similar behavior in the two climate conditions, with mean values around 0.8 m. This result is in accordance with the works of Vera-Puerto et al [38] (2021) and Vera et al [27], where TWs operated in Mediterranean and arid conditions, respectively, showed a height of 0.9 m in 6 months of growing for Schoenoplectus californicus and 0.70 m for Schoenoplectus americanus. In the case of Zantedeschia aethiopica (Za) in Mediterranean conditions, the height was affected and decreased from 0.6 m to around 0.20 m at the end of the experimental period.…”

“…In the case of chlorophyll, nondestructive methods (optical method) were employed. Because of the leaf thickness of Schoenoplectus californicus, chlorophyll content was measured at the top of the leaf according to Vera-Puerto et al [38], here at a point 10 cm before the leaf ending.…”

Reclamation of Treated Wastewater for Irrigation in Chile: Perspectives of the Current State and Challenges

“…Treatment wetlands have been recommended for this part of the population, this a technology in which natural processes are optimized to improve water quality and which has the possibility to produce treated wastewater of high enough quality to be reused as irrigation water in agricultural activities, following the circular economy concept [99][100][101][102][103]. However, at a national level, it has the lowest usage rate-below 2% in the rural sector [32]-despite several studies based on local experiences showing the potential for its use across the country [104][105][106][107][108].…”