Tratamento anaeróbio de esgotos domésticos

Abstract

The extremely bad quafüy of Jiving conditions of Brazilian population has, as one of its main causes, the Jack of sanitation services supply, in addition to the large urban concentration existing in Brazil, with one of the highest density metropolitan regions of the world. This fact points toward the search for technologies compatible to sueh actualities. This led to the development of the use of UASB reactor for sewage treatment. lnitially, tests wcre made with a 106l capacity UASB reactor, which showed the process feasibility and answered to the main typical questions of a new domestic sewage treatment system, e.g.its behaviour with hydraulic load variation, organic load and temperature. As positive results were obtained with this system at HRT = 4h and ambient tcmperature, i.c. effiuent values of 57 mg BOD/l, 155 mg COD/l and 59 mg SS/l, the tecnnology was tried out at demonstration scale looking for its further diffusion. A 120 ml UASB reactor was designed and constructed and its opcration confinned the results obtained in the pilot plant; i.e. HRT of 6.5 hours gave effiuents with 113 mg COD/l and 48 mg BOD/l and HRT of 4.7 hours gave effiuents with 132 mg COD/l and 59 mg BOD/l, always with an average SS-concentration of 45 mg SS/l. The investigated post-treatment processes gave a satisfactory polishing in terms of COD, BOD and disenfection of the effiuent. These rcsults clearly show that the UASB concept as sewage treatment system offers a new, simple and economical technological option for faeilitating the improvement of sanitary conditions of the country.