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Grisales, D.K., Ortega, L.J., Chaparro, R.TSanitation Laboratory, Civil Engineering Department, Military University, Bogota (Colombia). Carrera 11 No 101 80
Figure 1. Schematic of the wastewater treatment
The emerging pollutants have defined as a group of compounds that interfere with the functioning of endocrine systems. In most cases emerging contaminantscorrespond to unregulated pollutants, which may be candidates for future regulations. Hospital Wastewater (HWW) represents one of the most ubiquitous watersources in the total urban water cycles, where the generated effluents are usually loaded with pharmaceutical, chemical, radioactive and other toxic chemicalsubstances, as well as various pathogenic microorganisms (Rezaee et al. 2005). Hospital wastewaters are normally discharged directly without pre-treatment tosewers. Despite mostly being only a small fraction of the total wastewater volume in the influent of a sewage treatment plants (STP), Hospital wastewater hasgained increasing scientific and public attention in the last decade. This is part due to the HWW is considered as the major source of undesirable constituents.Several studies have demonstrated that the typical constituents of the HWW ( i.e antibiotics, anaesthetics, disinfectants, heavy metals) are not removed onconventional treatments, as a result may be founded on water sourced and can be related with environmental risks on human health. To our knowledge, only afew publications are related to the treatments of real HWW, the studies generally are limited to a synthetic hospital wastewaters or specific compounds. Moreover,studies on ecotoxicological impact of HWW are scarce.
Treatment Parameters Units References
Ozone
COD mg/L APHA (2005)
BOD mg/L
UV254 1/cm
pH ---
Residual ozone mg O3/L
Total toxicity % inhibition on the growth of roots of
Allium cepa L.Fiskesjo (1993)
e effect of ozonation at different initial pH and its impact on the total toxicity of real hospital wastewater was studied in this work. The results have demonstratedat the ozone application under different initial pH improves the hospital wastewater quality. At basic conditions the biodegradability ratio increases in 71% with anone dosage of 187 mgO3/L. However, at acidic conditions were founded the highest removal efficiency of UV254 and Colour (VIS436) In the case of the totalxicity the ozone promoted a reduction of 62% at basis conditions. In general, the military hospital wastewater varied considerably, thus the results in some cases
re inconsistent, indicating the requirement of additional studies for a whole monitoring of the water quality.
arameters Units Mean S.D --- 6.70.5
kalinity mg/L 37593
hloride mgCl-/L 15340
tal Solids mg/L 412143
OD mg/L 310123
OD5 mg/L 4637
OD/BOD5 ---- 7.64.3
V254 cm-1 0.670.4
S436cm-1 0.10.1
O4-2 mg/L 193.1
N mg/L 7.21.5
O4-2 mg/L
8.61.8
ecal ColiformCFU/mL 3.1 x 1062,3 x
106
le 2. Characteristics of the Hospital Wastewater
HA. (2005).Standard Methods for the Examination of Water and Wastewater21th. ed. American Public Health Association/American Water Works Association/Water Environment Federation, Washington,DC,USA. Fiskesjo, G.93). Allium test: A 2-3 day plant test for toxicity assessment by measuring the mean root growth of the onions ( Allium cepa L).Environmental Toxicology and Water Quality: An International Journal, 8, 461-470. Rezaee, A.,ari, M., Khavanin, A., Sabzali, A., Aryan, M.M. (200 5). Hospital wastewater treatment using an integrated anaerobic-aerobic fixed film bioreactor.American Journal of Environmental Sciences, 1 (4) , 259-263.
n our study real hospital wastewater was used to evaluate the effect of ozone at different initial pH. Moreover, was studied the total toxicity using bulbs ofAlliumepa L as bioindicator, before and after ozone application. This work could contribute practical knowledge for the treatment of real HWW using ozone as a pre-
treatment of subsequent biological process.
Ozone application
Production 188 mg.h-1
Reaction time (min) 15, 30, 45, 60
Volume 1000 mL
pH pH = 3,0 pH = 10, pH = without modification (6,7)
Table 1. Parameters evaluated
Table 2. Operational conditions of ozone application.
ral Military Hospital (Bogota Colombia)
Real Hospital Wastewater Ozone Reactor
stewater was obtained from the Central Military Hospital (CMH) located inot (Colombia). The CMH has a total of 1100 beds, 350,000 patients are
ved and offers all services of a modern hospital. Wastewaters are released intomain sewer of the Hospital from where it joins the citys sewerage system.s, the samples from this hospital were collected from the main sewer. Theuents were collected 4 times during the year 2011.
0 50 100 150 200
0.2
0.4
0.6
0.8
1.0
1.2
1.4
AbsorbanceatUV
254
(cm
-1)
Applied dose of ozone (mgO3/L)
pH 6.7
pH 3.0
pH 10
0 50 100 150 200
0.00
0.04
0.08
0.12
0.16
0.20
0.24
AbsorbanceatVIS
436
(Colour)(cm-1)
Applied dose of ozone (mgO3/L)
pH6.7
pH3.0
pH10
Figure 2. UV254 and VIS436 and applied ozone dosage
*S.D: standard deviation, n=4
The results in this study showed that the ozonation promotes the enhanced ofthe biodegradability of the HWW for the experiments conducted under differentinitial pH.
For pH = 3.0, COD/BOD increased in 40%. The increased biodegradability wascaused by an increase in BOD5 and concomitant decrease in effluent COD (4858%).
At pH = 10 the biodegradability ratio increase in 71%, and this wasconsequence of the increase of BOD5 in 40% and a slight COD decrease.
In both cases the increase in BOD5 provided the dominant contribution to thebiodegradability enhancement considering that COD decreased to a very
limited extend.
Effect on Biodegradaility
Effect on Toxicity
In our study we founded that the CMH wastewater without treatment results inan inhibition on the root growth of 69% and after ozone dose of 187 mgO 3/L andpH = 10 the inhibition percentage was reduced to 18%. In particular, ozonationat basic conditions resulted in a reduction of the total toxicity in 62%.
It is worth mentioning that not much work has been carried out about thetreatment of real HWW, thus the present study presents valuable knowledgeabout this type of effluents and the effects of ozone application.