Rural blackwater treatment by a full-scale Brazilian Biodigester Septic Tank: microbial indicators and pathogen removal efficiency

• Published in: Environmental science and pollution research international Vol. 28; no. 18; pp. 23235 - 23242
• Main Authors: Oliveira, Thaíssa Jucá Jardim, Santiago, Aníbal da Fonseca, Lanna, Maria Célia da Silva, Fongaro, Gislaine, Milagres, Natália Ladeira, Cunha, Thalita Ramos, Corrêa, Andreíza Liká Itó
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01-05-2021; Springer Nature B.V
• Subjects: Appropriate technology; Aquatic Pollution; Atmospheric Protection/Air Quality Control/Air Pollution; Blackwater; Coliforms; E coli; Earth and Environmental Science; Ecotoxicology; Effluent standards; Effluents; Enterococcus; Environment; Environmental Chemistry; Environmental Health; Environmental science; Escherichia coli; Hydraulic retention time; Microorganisms; Nuclear engineering; Nuclear safety; Research Article; Retention time; Salmonella; Septic tanks; Subsurface irrigation; Waste Water Technology; Water Management; Water Pollution Control; Blackwater reuse; Microbial indicators; Household biodigesters; Appropriate technology; Agricultural reuse; Enteric pathogens
• ISSN: 0944-1344; 1614-7499
• DOI: 10.1007/s11356-020-12229-2

The Brazilian Biodigester Septic Tank (BBST) is an on-site appropriate technology for blackwater treatment, which was developed to yield an effluent suitable for agricultural use. Although several studies have proven its efficacy for secondary blackwater treatment, there are few published studies about the microbiological quality of its effluent, and most of them focus on the quantification of total or thermotolerant coliforms. This study evaluates the performance of a BBST for the removal of human adenovirus (HAdV),
Enterococcus
spp.,
Salmonella
sp., and
Escherichia coli
. The results further clarify the safety and risks associated with the reuse of the obtained effluent. The full-scale system consists of three 1.2 m
3
interconnected reactors, with a blackwater input of 0.045 m
3
/day, and hydraulic retention time of 80 days. Six sample campaigns were performed at different stages of the monthly operating cycle. The system presented an average removal efficiency of 5.09 log
10
for
E. coli
, 3.22 log
10
for
Enterococcus
spp., 1.2 log
10
for
Salmonella
sp., and 3.0 log
10
for HAdV. According to the World Health Organization standards, the obtained effluent is suitable for subsurface irrigation, and for use in crops that develop distant from the soil or highly mechanized crop systems.