Considerations on design and implementation parameters of domestic wastewater treatment by subsurface flow constructed wetlands

Lis Eveline Athaydes Fadanelli,Maria Magdalena Ribas Döll,Alceu Gomes De Andrade Filho,Giovana Kátie Wiecheteck

doi:10.1590/s1413-41522019102334

Lis Eveline Athaydes Fadanelli, Maria Magdalena Ribas Döll + Show 2 more

Open Access

https://doi.org/10.1590/s1413-41522019102334

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Abstract

ABSTRACT Constructed wetlands might be an alternative for communities away from urban centers and not served by a domestic wastewater treatment system. The purpose of this study was to provide instructions for the implementation of subsurface flow constructed wetland systems. To that end, we gathered information regarding the construction aspect, plants, and operational parameters used in systems which already operate in the country and the respective efficiency of these sets after previous treatment. The system in real scale proposed by Oliveira et al. (2005) was prominent among those that presented the highest efficiency. It was preceded by upflow anaerobic reactor built in brick, with macrophyte of the Typha genre, crushed stone at the entry and exit of the system, and sand in its intermediate portion. It required 1.04 m² surface area per inhabitant in humid temperate climate and hot summer, 1.71 m³ d-1 flow, and one-day hydraulic detention. The considerations presented here might help the construction of this kind of system, regarding dimensional and operational criteria.

Highlights

Constructed wetlands have been presented as an alternative of decentralized sewage treatment, simulating a natural wetland environment, with basic ecological mechanisms (DORNELAS; MACHADO; VON SPERLING, 2009) allied to principles of Civil and Sanitary Engineering
Other important variables used to select the technology with the best overall performance were: identification of systems that preceded the constructed wetlands, construction aspects and dimensions, which made possible to establish the relation between the area needed to treat the wastewater generated per inhabitant (m2 inhab-1), later used to calculate the system implementation area (A), filling materials, and operational parameters
Among the treatment systems that preceded the horizontal flow constructed wetlands reported in the scientific literature, 28% were septic tanks and 20% were anaerobic reactors (Figure 1A)

Summary

Introduction

Constructed wetlands have been presented as an alternative of decentralized sewage treatment, simulating a natural wetland environment, with basic ecological mechanisms (DORNELAS; MACHADO; VON SPERLING, 2009) allied to principles of Civil and Sanitary Engineering. According to Costa et al (2003), who evaluated artificial wetlands in real-pilot scale at the Paraíba Federal University, the system had low cost and was easy to operate and maintain. These systems can be used as secondary or tertiary treatment composed by substrate, typical plant species, and microorganisms. Substrate creates empty spaces which serve as flow channels, making wastewater flow more according to its permeability, in addition to giving support to plants This support, along with the roots, provides the ideal place for nutrient removal and formation of microbial biofilm. The microbial biofilm developed in the rhizosphere of the real-pilot scale, comprising roots and substrate, consists of microorganisms that degrade organic matter, making the nutrients available to macrophytes (COSTA et al, 2003; PEDESCOLL et al, 2016)

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