Studies of filter media for zero-discharge systems collecting light greywater.
Zero-discharge constructed wetland environments are more prone to the accumulation of pollutants. The relationship between filter media and microbial communities in this type of environment is still poorly known. We conducted bench-scale studies of different filter media (polyurethane foam, blast-furnace slag, and loofah) in these systems by simulating the batch operation with light greywater for 433 days. Physicochemical and microbiological analyses (scanning electron microscopy and polymerase chain reaction electrophoresis denaturing gradient gel) were used. In all systems, anoxic environments prevailed. These environments were crucial for methanogenesis and sulfidogenesis processes, which are primarily responsible for organic material conversion. The chemical oxygen demand/sulfate (COD/SO42-) ratio was the limiting factor in the competition of microorganisms involved in these processes. This condition, combined with the neutral-alkaline pH, also allowed Chloroflexi phylum bacteria to oxidize sulfide to sulfate and elemental sulfur in all studied media. The results showed strong evidence supporting that the microbial community formed in the present study is more related to operational/environmental conditions than to the different tested filter media. Thus, this demonstrates that the control of interactive effects between pH, redox potential, and the COD/SO42-ratio can prevent the accumulation and/or release of sulfide in anoxic environments.
a Faculty of Engineering, Architecture and Urbanism and Geography , Federal University of Mato Grosso do Sul , Campo Grande , MS , Brasil.
Fernando Silva
http://orcid.org/0000-0002-0015-3766
FS
Bernardes
b Department of Sanitary and Environmental Engineering , Federal University of Minas Gerais (UFMG) , Belo Horizonte , MG , Brasil.
Renata Cortes
http://orcid.org/0000-0003-3707-7055
RC
de Oliveira Diniz
b Department of Sanitary and Environmental Engineering , Federal University of Minas Gerais (UFMG) , Belo Horizonte , MG , Brasil.
Juliana Calábria
http://orcid.org/0000-0002-5497-8675
JC
Araújo
a Faculty of Engineering, Architecture and Urbanism and Geography , Federal University of Mato Grosso do Sul , Campo Grande , MS , Brasil.
Paula Loureiro
http://orcid.org/0000-0002-8091-6486
PL
Paulo
D001419:Bacteria; D013431:Sulfates; D013440:Sulfides; D013455:Sulfur; D062065:Wastewater; D053833:Wetlands
D013431:Sulfates; D013440:Sulfides; D013455:Sulfur; D062065:Wastewater
Grey water; constructed wetlands; microbial analysis; source separation; support media