Poster presented at a conference "Water Research at University of Oulu". The poster presents some disinfection results with peracetic acid in wastewater and sludge matrixes.

1. Water and wastewater treatment applications of peroxides
Tero Luukkonen1, Hanna Prokkola1, Jaakko Rämö3, Ville Kaikkonen1 and Ulla Lassi1,2
University of Oulu, Department of Chemistry, FIN-90014 University of Oulu, P.O.Box 3000
2
Kokkola University Consortium Chydenius, Talonpojankatu 2B, FIN-67100 Kokkola
3
University of Oulu, Thule Institute, FIN-90014 University of Oulu, P.O. Box 7300
1
INTRODUCTION
Peroxides are widely used in water and wastewater treatment
applications such as wastewater disinfection1,2, odour abatement3,
wastewater sludge treatment4 and remediation of anoxic lakes and
sediments5. Most important peroxides used in these applications include
hydrogen peroxide (HP), peracetic acid (PAA), performic acid (PFA) and
solid calcium and magnesium peroxides. Peroxides can be accompanied
with a specific physical or chemical activating treatment. The combinations
are then called advanced oxidation proceseses (AOPs). Examples of
AOPs include UV/HP, UV/PAA, UV/PFA, O3/HP or Fe/HP (the Fenton
reaction). AOPs can be used to oxidize recalcitrant pollutans in water such
as pharmaceutical residues or as a coagulation aid.
Objectives of this research are to test disinfection efficiency of PAA in
different matrixes such as secondary and tertiary wastewater and
wastewater sludge. Also, the factors affecting the disinfection efficiency
are evaluated.
Fig. 1. Disinfection results of municipal wastewater expressed
EXPERIMENTAL
as a function of C * t (concentration of PAA * contact time).
Laboratory scale batch tests were performed for samples of secondary
municipal wastewater and municipal wastewater sludge. Tests were done
by dosing PAA chemical (PACS12), mixing sample and quenching the
residual PAA with sodium thiosulphate after specific contact time.
Indicator microbes (total coliform bacteria form wastewater and E. coli
from sludge) were analyzed to assess the microbial quality after treatment.
Chemical quality of wastewater and sludge samples was analyzed: BOD 7,
COD, total suspended solids and pH. Results are shown in Table 1.
Table 1. Chemical quality of samples before disinfection.
BOD7 [mg/l]
COD [mg/l]
Solids
pH
Wastewater
4
56
< 5 mg/l
7.2
Sludge
3250
-
54 000 mg/l
6.7
Fig. 2. Disinfection results of municipal wastewater sludge
RESULTS AND DISCUSSION
b)
expressed as a function of applied PAA dose.
DISINFECTION OF MUNICIPAL WASTEWATER
The sample was collected from a wastewater plant using a conventional
active sludge process which was followed by sedimentation. No tertiary
filtration was employed. The coagulant applied at the plant was
polyaluminium chloride. The disinfection behaviour is characterized by a
sharp initial decrease in bacteria amount which is followed by slower
inactivation as the dose or contact time is increased (Fig. 1).
DISINFECTION OF MUNICIPAL SLUDGE
Figure 2 shows the disinfection results of a municipal wastewater sludge
sample. The sample was a combination of primary and excess biological
sludges and it was taken after the thickening unit operation in sludge
treatment. Results indicate that significantly higher doses of disinfectant
are required for sludge compared to wastewater which is due high solid
concentration and BOD.
REFERENCES
1. Gehr R, Chen D & Moreau M (2009) Performic acid (PFA):
Tests on an advanced primary effluent show promising disinfection
performance. Water Science and Technology 59(1): 89-96.
2. Kitis M (2004) Disinfection of wastewater with peracetic acid: A
review. Environ Int 30(1): 47-55.
3. Sims AFE (1980) Odour control with hydrogen peroxide.
Progress in Water Technology 12(5): 609-620.
4. Appels L, Assche AV, Willems K, Degrève J, Impe JV & Dewil R
(2011) Peracetic acid oxidation as an alternative pre-treatment for
the anaerobic digestion of waste activated sludge. Bioresour
Technol 102(5): 4124-4130.
5. Nykänen A, Kontio H, Klutas O, Penttinen O-, Kostia S, Mikola J
& Romantschuk M (2012) Increasing lake water and sediment
oxygen levels using slow release peroxide. Sci Total Environ 429:
317-324.