IMPACT OF THE HYDRAULIC LOADING RATE ON THE HYDRODYNAMIC CHARACTERISTICS OF AN ANAEROBIC FIXED BED REACTOR TREATING CATTLE SLAUGHTERHOUSE WASTEWATER

Cristiane Kreutz,Aldria D Belini,Simone D Gomes,Fernando H Passig,Cláudia S De C M Dos S Cordovil Cordovil,Karina Q De Carvalho

doi:10.1590/1809-4430-eng.agric.v38n3p403-410/2018

Abstract

The hydrodynamic behavior of an anaerobic fixed bed reactor (AFBR) was evaluated in the treatment of cattle slaughterhouse wastewater. The AFBR was operated at hydraulic retention time (HRT) of 14, 11 and 8 h. Stimulus-response assays were carried out with eosin Y and the experimental data were adjusted to the single-parameter theoretical models of dispersion and N-continuous stirred tank reactors in series. The experimental results of the residence time distribution curves showed that at lower flowrate, the reactor showed plug flow behavior with R2 of 0.88 and number of dispersion of 0.2 for high dispersion (HD). However, at higher and intermediate flowrates, the AFBR behave as a complete mixture flow, with R2 of 0.94 and 0.96, respectively. Residence time distribution curves in the AFBR showed a good approximation of the complete mixing model at hydraulic residence time of 11 h and 8 h, with 5 and 2 N-CSTR reactors in series, respectively. The volume of dead zones corresponding to 43.0%, 37.4% and 11.2% of the volume of the reactor for HRT of 14 h, 11 h and 8 h, respectively, was noted, and hydraulic short-circuiting were not confirmed.

Highlights

Most of the meat slaughterhouse wastewater is composed of high organic matter concentrations, nutrients such as nitrogen and phosphorus and pathogens and nonpathogenic microorganisms (Debik & Coskun, 2009; Cao & Mehrvar, 2011; De Nardi et al, 2011)
Residence Time Distribution curves can help in the establishment of flow regimes, determination of the hydrodynamic parameters and identification of flow anomalies inside the reactor
Experimental hydraulic retention time showed an average delay of approximately 75.7%, 60.9% and 12.5% compares to the theoretical HRT of 14, 11 and 8 h, respectively

Summary

INTRODUCTION

Most of the meat slaughterhouse wastewater is composed of high organic matter concentrations, nutrients such as nitrogen and phosphorus and pathogens and nonpathogenic microorganisms (Debik & Coskun, 2009; Cao & Mehrvar, 2011; De Nardi et al, 2011). Residence Time Distribution curves can help in the establishment of flow regimes (plug flow, complete mixture flow or both), determination of the hydrodynamic parameters (real θ, number of reactors in series, dispersion number, tracer recovery and hydraulic efficiency) and identification of flow anomalies inside the reactor (dead zones, preferential paths and/or hydraulic short circuits). These anomalies may reduce the efficiency of the reactors treating wastewater due to the decrease of useful volume and hydraulic retention time required to the performance of the microbial activity as noted by Abbas et al (2015). In the second part of this research, starting from the hydrodynamic results, the anomalies dead zones and hydraulic short circuiting were evaluated and hydraulic efficiency was calculated

MATERIAL AND METHODS

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RESULTS AND DISCUSSION

CONCLUSIONS