First stage of the French vertical flow constructed wetland system: experiments with the reduction of surface area and number of units

Abstract

Small vertical-flow constructed wetland units comprising the first stage of the French system were studied in Brazil for the treatment of raw sewage. Planted and unplanted units and different feeding strategies were tested. In the first phase, hourly batches of a daily flow of 13 m3 d−1 were applied over three alternating units, resulting in an average hydraulic loading rate (HLR) on the full system of 0.15 m3 m−2 d−1. A second phase, aimed at reducing land requirements, kept the same daily flow and batch frequency, but used two alternating units, resulting in a HLR on the full system of 0.22 m3 m−2 d−1. Removal efficiencies were very good when the system operated with three units, with mean values of 82% for biochemical oxygen demand (BOD), 81% for chemical oxygen demand (COD), 85% for total suspended solids (TSS) and 59% for NH4+-N. With two units, the equivalent values were 74% for BOD, 59% for COD, 67% for TSS and 51% for NH4+-N. There were significant differences in the median removal efficiencies of COD and TSS. No significant differences were found between planted and unplanted units for most constituents. In both phases, the overall good performance and the simplicity of the system make this treatment process a very attractive alternative for developing countries.

Review of the Greywater and Proposed Greywater Recycling Scheme for Agricultural Irrigation Reuses

“…There were no significant differences between planted and unplanted VFCW systems for most constituents removal. Both had good performance, and the simplicity of the system makes this treatment process a very attractive one (Manjate et al, 2015). Morover, the payback period of the RVFCW was about three years, and the system can be run and maintained by unskilled operators (Ghaitidak and Yadav, 2013).…”

Performance evaluation of different macrophytes in small‐scale vertical flow constructed wetlands for greywater treatment using principal component analysis

“…[ 52 ] TKN removal efficiencies of 9% and 20% for VFCW systems planted with E. crassipes and unplanted VFCW systems with an influent concentration of 34.71 mg/L, respectively, were recorded by Mello et al [ 22 ] The removal efficiency reported in the literature is on the lower side. In contrast, Manjate et al [ 53 ] reported 56% removal of TKN with Cynodon spp., which had an influent concentration of 31 mg/L for sanitary wastewater.…”

“…Assimilation by biofilms, plant absorption, adsorption, and ammonia volatile ionization were the most likely removal mechanisms in the studied systems, as indicated in the literature. [ 52 ] In contrast, Manjate et al [ 53 ] reported that a Cynodon spp. planted system had a TKN removal efficiency of 56%, whereas an unplanted system had a TKN removal efficiency of 47%, with a significant concentration of 31 mg/L for sanitary wastewater.…”

In-depth assessment of microbial communities in the full-scale vertical flow treatment wetlands fed with raw domestic wastewater

“…This activity is the main factor responsible for the treatment performance and durability of the system. Furthermore, the French VF wetland has been adapted in a number of climates, such as cold [3,4] and tropical climates [5][6][7], which would add another layer of variability to the microbiota distribution. Improving knowledge of microbial diversity and dynamics, together with the physicochemical results and their relationship with systems operation and efficiency, could help inform the system design and operation mode, thus improving the performance of French VF wetland.…”