Aclimatação de biomassa Anammox® em reator MABR visando à remoção de nitrogênio de efluente de abatedouro de aves

Abstract

Research into advanced nitrogen removal processes, such as the deammonification pathway, is particularly interesting in regions with high slaughterhouse density that generates a large volume of nitrogen-concentrated effluents. There are investigative gaps related to biomass sources and robust reactors that can promote a rapid start-up of this process. The present research aimed to enrich Anammox® biomass in membraneaerated biofilm reactors (MABR), which carried out the deammonification process (partial nitration/Anammox activity in a single reactor), fed in sequencing batch (MABR-BS) and continuous flow. The MABR is a reactor with an internal microporous silicone membrane, where air circulates inside and the end of membrane stayed emerged in a water column, under over pressure that makes the air get out to membrane microporous, and the biofilm is developed outside. The methodology was divided into three steps: i) Biomass enrichment in sequential batch MABR reactors; ii) With the best result from the previous step, the same sludge source was used to inoculate a continuous flow MABR reactor; iii) The biomass enriched in stages 1 and 2 was used in the inoculation of the same reactor as in stage ii, which is then fed with effluent from poultry slaughter. In step (i), three sources of sludge were used: 1) UASB reactor, which treats domestic sewage; 2) ETElandfill leachate; and 3) ETE-slaughter effluents. Three nitrogen loading rates (NLR) were studied, namely: 0.005; 0.0083 and 0.025 KgN.m-3.d-1, under controlled conditions of temperature and agitation at 32°C and 30 rpm. In step (ii), the MABR with continuous feed was tested with hydraulic detention time (TDH) of 5, 3, and 1 day (NLR: 0.02, 0.01, and 0.1 KgN.m-3.d-1) fed with synthetic effluent. The reactor was recirculated in a 1:1 ratio, kept at a controlled temperature of 32°C, and pH between 7.5 and 8.5. In step (iii), an MABR was fed with effluent collected at the exit of the stabilization anaerobic pond of a slaughterhouse located in the western region of Paraná, and the TDH of 24, 16, and 12 h were tested. In the first stage, all reactors reached Anammox® activity, noticed after 20 days of operation; the best N removal performance was in the reactor inoculated with anaerobic sludge from ETE-domestic sewage. This same sludge was used in step (ii), in which the Anammox® activity was initially verified, but due to the alkalinity shock in the medium, the reactor lost stability, and re-inoculation was necessary. In step (iii), the reactor adapted to the wastewater within eight days, with a TDH of 24 hours, with 91% of average efficiency in N removal, requiring only alkalinity correction. The research objectives were achieved; all reactors developed Anammox® bacteria (Candidatus Anamoxiglobulus Propionicus), and the R1 UASB reactor was a highlight in this process.