Estudo da retenção de fósforo e do comportamento dos colifagos somáticos e bacteriófagos F- específicos em um sistema de terra úmida construída.

Abstract

Constructed wetlands systems are used for superficial polluted water and sewage purifícation through physical, chemical and bioiogical process which occur naturally in the ecosystem and, in this way, reduce loadings of sediments, nutrients and pollutants to recipient lakes and rivers, ímproving me water quality. The used of these systems is increasing ín ali over the world, with different climates conditions. This work aimed the analysis of the performance of constructed wetland system, with subsurface runoff, in pilot scale, fed with water from a polluted creek. Total phosphorus, faecal coliforms (termotolerants) and coliphages (somatics -CS and F- specifícs - BF+) removais were evaluated during 9 months in the constructed wetland system cultivated with Typha spp. and rice (Oriza sativa L.) using gravei and sand as substrate media. The constructed wetlands system comprised 18 experimental tanks (250L each) with gravei (19mm - 9 tanks ) and sand (other 9 reservoirs) having hydraulic retention time of 10 days. Three tanks with gravei were vegetated with Typha spp., other three with rice and three without vegetation were kept as control. The same distribution was made with the tanks with sand. The sand promoted better removais for coliforms, CS and CF+ with or without vegetation. The combination of gravei plus Typha spp. showed the highest removal for Total Phosphorus (53,24%). The removal of this parameter in the units with sand and gravei with rice after two rice collections were highest than the removais in the control tanks. Vegetated TUCs showed highest values of total phosphorus than controls TCs. The phosphorus distribution study showed that sand substrate cumulated three times more phosphorus than gravei substrate. The rice phytomass cumulated during both two growth cycles (4 months each) three times more phosphorus than Typha spp (one growth cycle - 9 months) without substrate influence (sand or gravei). The aerial part of the plants (rice and Typha leaves) showed fluctuarions with faecal coliforms (termotolerants) contamination. The faecal contamination confirmed with E.coli leveis was very low and the highest values of termotolerant coliform probably were of environmental origin