O. Reyes et al., A COMPARATIVE-STUDY OF SAND AND NATURAL ZEOLITE AS FILTERING MEDIA INTERTIARY-TREATMENT OF WASTEWATERS FROM TOURIST AREAS, Journal of environmental science and health. Part A: Environmental science and engineering, 32(9-10), 1997, pp. 2483-2496
Anaerobic effluents from a fixed bed reactor treating sewage water fro
m tourist areas were treated by two high rate filters at laboratory sc
ale one packed with sand and the other with natural zeolite with the a
im of obtaining final effluents with quality for irrigation of land or
disposal in tourist zones. The ranges of particle sizes for the two f
iltering media used were: 1-3 mm and 0.6-2.5 mm for both media and par
ticle sizes of 0.35-1 mm also for the zeolite. The evaluation of diffe
rent particle sizes demonstrated that the particle range of 1-3 mm for
both media was more effective than the rest of size ranges studied in
the removal of pollutant particles. It was found that turbidity remov
al was similar for sand and zeolite although the filter packed with ze
olite had lower pressure losses and better hydraulic behaviour. A maxi
mum ammonia nitrogen removal of 95% was obtained in the first hour of
filtration for zeolite medium, although the removal decreased progress
ively achieving a minimum value of 50% at 8 h of operation. The ammoni
a nitrogen removal values were always higher than those observed in th
e sand bed. For the smallest particle size (0.35-1 mm) of the zeolite
bed, the total coliforms removal was near to 100%, while for the other
particle sizes the removal percentages were in the range of 90-96% wi
thout significant differences between sand and zeolite. Therefore, the
final concentration of total coliforms obtained after the filtration
with zeolite (0.35-1 mm) can be considered adequate for water reuse in
land irrigation.