Removal of micro-organisms in a small-scale hydroponics wastewater treatment system.
OBJECTIVE
To measure the microbial removal capacity of a small-scale hydroponics wastewater treatment plant.


RESULTS
Paired samples were taken from untreated, partly-treated and treated wastewater and analysed for faecal microbial indicators, i.e. coliforms, Escherichia coli, enterococci, Clostridium perfringens spores and somatic coliphages, by culture based methods. Escherichia coli was never detected in effluent water after >5.8-log removal. Enterococci, coliforms, spores and coliphages were removed by 4.5, 4.1, 2.3 and 2.5 log respectively. Most of the removal (60-87%) took place in the latter part of the system because of settling, normal inactivation (retention time 12.7 d) and sand filtration. Time-dependent log-linear removal was shown for spores (k = -0.17 log d(-1), r(2) = 0.99).


CONCLUSIONS
Hydroponics wastewater treatment removed micro-organisms satisfactorily.


CONCLUSIONS
Investigations on the microbial removal capacity of hydroponics have only been performed for bacterial indicators. In this study it has been shown that virus and (oo)cyst process indicators were removed and that hydroponics can be an alternative to conventional wastewater treatment.
Ottoson
J
J
Department of Parasitology, Mycology and Water, Swedish Institute for Infectious Disease Control, Solna, Sweden. jakob.ottosson@smi.ki.se
Norström
A
A
Dalhammar
G
G
D003016:Clostridium perfringens / Q000302:isolation & purification; D003090:Coliphages / Q000302:isolation & purification; D015169:Colony Count, Microbial; D016983:Enterococcus / Q000302:isolation & purification; D004926:Escherichia coli / Q000302:isolation & purification; D018527:Hydroponics; D013171:Spores, Bacterial / Q000302:isolation & purification; D013548:Sweden; D010948:Viral Plaque Assay; D014871:Water Microbiology; D018508:Water Purification / Q000379:methods*