Assessment of indoor airborne contamination in a wastewater treatment plant.
The main objective of this work was to quantify and characterize the major indoor air contaminants present in different stages of a municipal WWTP, including microorganisms (bacteria and fungi), carbon dioxide, carbon monoxide, hydrogen sulfide ammonia, formaldehyde, and volatile organic compounds (VOCs). In general, the total bacteria concentration was found to vary from 60 to >52,560 colony-forming units (CFU)/m(3), and the total fungi concentration ranged from 369 to 14,068 CFU/m(3). Generally, Gram-positive bacteria were observed in higher number than Gram-negative bacteria. CO(2) concentration ranged from 251 to 9,710 ppm, and CO concentration was either not detected or presented a level of 1 ppm. H(2)S concentration ranged from 0.1 to 6.0 ppm. NH(3) concentration was <2 ppm in most samples. Formaldehyde was <0.01 ppm at all sampling sites. The total VOC concentration ranged from 36 to 1,724 μg/m(3). Among the VOCs, toluene presented the highest concentration. Results point to indoor/outdoor ratios higher than one. In general, the highest levels of airborne contaminants were detected at the primary treatment (SEDIPAC 3D), secondary sedimentation, and sludge dehydration. At most sampling sites, the concentrations of airborne contaminants were below the occupational exposure limits (OELs) for all the campaigns. However, a few contaminants were above OELs in some sampling sites.
LSRE-Laboratory of Separation and Reaction Engineering-Associate Laboratory LSRE/LCM, Faculdade de Engenharia, Universidade do Porto, Rua Dr. Roberto Frias, 4200-465 Porto, Portugal.
Juliana V
JV
Teixeira
Sandra
S
Miranda
Ricardo A R
RA
Monteiro
Filipe V S
FV
Lopes
Joana
J
Madureira
Gabriela V
GV
Silva
Nazaré
N
Pestana
Eugénia
E
Pinto
Vítor J P
VJ
Vilar
Rui A R
RA
Boaventura
D000391:Air Microbiology; D000393:Air Pollutants / Q000032:analysis*; D016902:Air Pollution, Indoor / Q000032:analysis* / Q000706:statistics & numerical data; D000641:Ammonia / Q000032:analysis; D001419:Bacteria / Q000254:growth & development / Q000302:isolation & purification; D002245:Carbon Dioxide / Q000032:analysis; D002248:Carbon Monoxide / Q000032:analysis; D004784:Environmental Monitoring; D005557:Formaldehyde / Q000032:analysis; D005658:Fungi / Q000254:growth & development / Q000302:isolation & purification; D006801:Humans; D006862:Hydrogen Sulfide / Q000032:analysis; D016273:Occupational Exposure / Q000706:statistics & numerical data; D055549:Volatile Organic Compounds / Q000032:analysis; D014865:Waste Disposal, Fluid / Q000706:statistics & numerical data*
D000393:Air Pollutants; D055549:Volatile Organic Compounds; D002245:Carbon Dioxide; D005557:Formaldehyde; D000641:Ammonia; D002248:Carbon Monoxide; D006862:Hydrogen Sulfide