Granulação de lodo aeróbio em reatores de bateladas seqüenciais visando a remoção de matérias orgânico e nutrientes de esgoto doméstico.

Abstract

The numerous studies on liquid waste treatment combine a search for alternatives that are efficient from the treatment point of view and economically viable. Conventionally, activated sludge systems are operated in a continuous flow regime, where a reactor or a series of reactors continuously receive raw influent to be treated. However, the treatment in the form of sequential batches manages to group all units of the treatment operation in a single tank. conventional, reducing the area for the installation of the reactors and optimizing the steps of the process. A new aspect for these reactors is the formation of aerobic granular sludge, which has been the objective of scientific research and presents several advantages compared to reactors operated with flocculent sludge, among which can be mentioned: better sludge settleability, simultaneous removal of phosphorus and nitrogen and ability to withstand variations of organic loads. The present work sought the granulation process to evaluate the use of domestic reactors operating in sequential batches, aiming at the replacement of organic material, phosphorus nitrogen and biological effluent. Four different operational conditions applied to a pilot reactor (useful volume of 471 liters) were investigated, varying the concentration of dissolved oxygen supplied to the system. As a way to verify the granulation process, the dynamic sedimentability test was used as a parameter. For the investigations studied, it was found that the operational configurations imposed on experiments II and IV were favorable for the formation of granules, reaching a maximum percentage of up to 50% of granules in investigation IV. However, the complete granulation of the sludge was not verified, given that obtaining granules by treating domestic sewage requires a longer operating time of the system, which was not possible, due to the anticipation of the conclusion of the research due to the COVID-19 pandemic. The study also showed that as an alternative to the sludge volumetric index test, the settleability test provides greater reliability for the results of sludge development of granules, which associated with the granulometric test define the characteristics of the sludge. For the other parameters (organic material, nitrogen and phosphorus) both investigations showed satisfactory performance, obtaining an average removal of organic material around 90%, ammonia nitrogen

oxidation also around 90%, maximum phosphorus absorption of 18 .6 mg.P-PO43-.L- 1. During the investigations incomplete nitrification and relatively high residual

concentrations of nitrite and nitrate were observed. With 15 mg.N-NO2-, for investigations of II and IV, and nitrate above 10 mg.N-NO3-.L-1, for investigations I and III. In this case, it is concluded that the treatment system using aerobic granules has great treatment capacity, mainly in terms of phosphorus absorption, generating high quality effluent.