Nature's way, Our way

Studies

ABSTRACT FOR RBC-PMT STUDIES CONDUCTED BY UNIVERSITY OF SAN CARLOS CHEMICAL ENGINEERING DEPARTMENT (2007-PRESENT)

 

Post-treatment of Brewery Wastewater Using the Rotating Biological Contactor

Joshua D. Bereso, Juan Paulo J. Mozar, Angelo H. Cabije*
Department of Chemical Engineering, University of San Carlos, Talamban Cebu City 6000, Philippines
*Corresponding Author: Telefax +63 32 344 6783

Abstract
The applicability of a single-stage rotating biological contactor -packed media technology ( RBC-PMT) as post-treatment of an Upflow Anaerobic Sludge Blanket (UASB) effluent from brewery was assessed using two different flow rates 20 ml/min and 9 ml/min (with corresponding organic loading rates, 2.1 and 0.87 g soluble COD/m2-day). The operation of the RBC is set at 5 rpm, 40% contactor submergence and open-aerated. Respectively, the removal rates for the COD and phosphate and formation of nitrate at 20ml/min flow rate are 49.01%, 18.41%, 17.61%; and at flow rate of 9ml/min, the removal rates for the COD and phosphate and formation of nitrate are 38.63%, 20.88% and 29.22% respectively. Organic removal and nitrification was simultaneously effected in one process, hence the condition is an ideal solution to water pollution control.

Keywords: RBC, UASB, brewery wastewater, post-treatment


Nitrification and Denitrification of Ammonia-rich Wastewater in a Rotating Biological Contactor

Leah G. Candilosas, Scott Dreuben A. Ponce, Reena Ross E. Villegas, Angelo H. Cabije*
Department of Chemical Engineering, University of San Carlos, Talamban Cebu City 6000, Philippines
*Corresponding Author: Telefax +63 32 344 6783,

Abstract

Nitrification and denitrification of synthetic ammonia-rich wastewater in a laboratory scale Rotating Biological Contactor-Packed Media Technology (RBC-PMT) was investigated using an open and a covered setup. Microorganisms were inoculated into the system. The two experimental runs were conducted under ambient conditions and the pH of the system was maintained at 6 to 7. The rotational speed of the contactor and the flow rate were set constant at 4 rpm and 28.8 L/day, respectively. For the uncovered setup, at the average DO of 6.08 mg/L, the extent of nitrification is 60.09%. For the covered setup, at the average DO of 4.91 mg/L, the extent of nitrification and denitrification is 54.04% and 10.61%, respectively.

Keywords: Rotating Biological Contactor, nitrification, denitrification


Carbon-Nitrogen-Phosphorus Removal and Biofilm Growth Characteristics in an Integrated Wastewater Treatment System Involving a Rotating Biological Contactor

Angelo H. Cabije*, Ramelito C. Agapay, and May V. Tampus
Department of Chemical Engineering, University of San Carlos, Talamban, Cebu City 6000, Philippines
*Corresponding author: Telefax +63 32 254 5784,

Abstract

A new rotating biological contactor-packed media technology (RBC-PMT) is locally innovated using light polyethylene Amazon screen material as disc media. A single-stage co-current fed of this type which is connected with a series of equalization tanks as an integrated wastewater treatment system showed good Carbon-Nitrogen-Phosphorus (C-N-P) removal and unveiled biofilm growth characteristics noteworthy for treating pollutants in wastewater.

The equalization tanks approached facultative-anaerobic conditions while the RBC-PMT exhibited a completely aerated system, both with a slightly alkaline pH, whose temperatures are ranging from 21 ºC to 24 ºC, and both performed as biological nutrient removal systems. The combined nutrient removal efficiency at high organic loading rate (HOLR) and low organic loading rate (LOLR) showed fair COD removal at 65.68% and 67.89%, respectively. Nitrate-nitrogen removal demonstrated good removal at 79.17% at HOLR and 83.43% at LOLR. There was excellent phosphate-phosphorus removal determined at 91.64% and 94.35% at high and low organic loading rates, respectively. This indicates that increasing the organic loading rate decreases the C-N-P removal in the integrated wastewater treatment system.

The anaerobic condition in the equalization tank was manifested by the distinct rotten egg odor of the hydrogen sulfide gas and the blackish discoloration of stored wastewater, while nitrification/denitrification at the RBC-PMT was considered by the presence of distinct fishy odor of ammonia gas produced by microbial action, particularly during the first few days of operation. Biofilm growth was characterized by the selection and survival of microorganisms present under aerobic environmental conditions in the RBC-PMT system and their respective metabolism in removing C-N-P substrates. Yeasts, coliform bacteria particularly E. coli, cyanobacteria, and benthic diatoms were dominant microorganisms found upon oil-immersion microscopy. Protozoans and algae including Chlorococcum, Chlorella, Diatoma, Tribonema, Oscillatoria, Euglena and other motile rotifiers were also dominantly found in the biofilm samples. Biofilm growth is observed and its average thickness was measured to be 7.71 μm at HOLR and 2.81 μm at LOLR. Thicker biofilm at HOLR has caused the reduced rate of diffusion of the microorganisms and their metabolic products as manifested by the low C-N-P removal during high organic loading rate.

Keywords: Rotating Biological Contactor-Packed Media Technology (RBC-PMT); biofilm; biofilm thickness, microorganisms; C-N-P removal; biological nutrient removal; organic loading rate; integrated wastewater treatment system.


Mixing Characteristics of Rotating Biological Contactor-Packed Media Technology (RBC-PMT) using Tracer Analysis

Mair Angelie Q. Barrot, April N. Oliveros, Ivy Theresa A. Saavedra, May V. Tampus*
Department of Chemical Engineering, University of San Carlos, Talamban, Cebu City 6000, Philippines
*Corresponding author: Telefax +63 32 344 6783,

Abstract

A tracer study on Rotating Biological Contactor-Packed Media Technology (RBC-PMT) was conducted in order to investigate its mixing characteristics in terms of the residence time distribution (RTD). From the RTD, E(t)-curve was generated. This curve describes the fraction in a quantitative manner how much time different fluid elements have spent in the reactor.

The residence time distribution of the reactor was determined experimentally by injecting 36% (w/w) sodium chloride (NaCl) solution as tracer. The experiment was conducted by varying the influent flow rate to 0.02-m3/hr and 0.07-m3/hr as the low and high flow rate, respectively, and the shaft rotational speed to 3 and 5-rpm. From the residence time distribution, it was found out that the reactor behaves non-ideally. Using tank-in-series model, the RBC-PMT approximates a 2 tanks-in-series reactor configuration.

Keywords: Rotating Biological Contactor-Packed Media Technology (RBC-PMT); tracer analysis; residence time distribution (RTD)

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