An analysis of the factors that influence biological phosphorous removal (BPR) in a sequencing batch anaerobic/aerobic reactor

Ca. 60 % of the Dutch activated sludge plants consist of completely mixed systems, experiments have been carried out in completely mixed pilot plants to study the biological P-removal. The research was carried out in two pilot plants. The pilot plants consisted of: anaerobic reactor, anoxic reactor, aerobic reactor and a clarifier. All the reactors were completely mixed. Both plants were fed with settled domestic waste water at a sludge loading of 400 and 250 g COD/kg sludge.day respectively. The results are given below:sludge loading (g COD/kg sludge.day)400400250ratio Anaerobic : Anoxic : Aerobic1: 1:2,71:1:4,11:1:2,7P-removal (%)802875N-removal (%)505065COD-removal (%)858585 It has been shown that there is no significant difference between the results at the two different sludge loadings. Remarkable is the difference between the ratio 1:1:2,7 in combination with the internal recirculation flow anoxic-anaerobic of 160 % and the ratio 1:1:4,1 with a recirculation flow of 30 %. During the start-up at a sludge loading of 250 g COD/kg sludge.day and an internal recirculation flow of 30 %, bulking sludge developed almost immediately. The Premoval was completely disturbed. Increasing the internal recirculation flow to 160% had a positive effect on settling properties and P-removal. This investigation has pointed out that a completely mixed system is suitable for biological P-removal, without negatively affecting the nitrification. Important factors in the process are the ratio anaerobic:anoxic:aerobic and the recirculation flows.

Download Full-text

An improved small sewage treatment plant for biological purification of wastewater

Water Science & Technology ◽

10.2166/wst.1994.0575 ◽

1994 ◽

Vol 29 (12) ◽

pp. 23-29 ◽

Cited By ~ 3

Author(s):

G. Voigtländer ◽

E.-P. Kulle

Keyword(s):

Energy Supply ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Septic Tank ◽

Additional Energy ◽

Anaerobic Reactor ◽

Step Process ◽

Operational Costs ◽

Aerobic Reactor

The paper presents a small sewage treatment plant (package plant) operating without additional energy. Purification of sewage is achieved in a three-step process: sedimentation tank, anaerobic reactor and wastewater pond or aerobic reactor. The efficiency of the anaerobic reactor - in contrast to the efficiency of a common septic tank - is significantly increased by using fixed biomass systems. Further degradation of sewage compounds by adhering microorganisms occurs in pond or aerobic reactor. The bed for the aerobic biomass is made of a semipermeable plastic film and arranged in order to ensure simultaneous supply of oxygen. The three pilot plants are showing different results. The main aims of research i.e. lowering of operational costs, energy supply, minimizing of maintenance expenditure and cleaning work, reliability of degradation efficiency have been achieved so far for the anaerobic reactor.

Download Full-text

CHARACTERISATION OF THE NITRIFICATION PROCESS FOR DESIGN PURPOSES

Water Science & Technology ◽

10.2166/wst.1994.0155 ◽

1994 ◽

Vol 30 (4) ◽

pp. 47-56 ◽

Cited By ~ 3

Author(s):

O. Sinkjær ◽

L. Yndgaard ◽

P. Harremoës ◽

J. L. Hansen

Keyword(s):

Kinetic Theory ◽

Nitrification Rate ◽

Experimental Basis ◽

Batch Tests ◽

Mode Of Operation ◽

Nitrification Process ◽

Aerobic Reactor ◽

The City ◽

Specific Evaluation ◽

Aerobic Sludge

Pilot plant experiments have been performed over a period of four years in order to establish an experimental basis for the upgrading of the treatment plants of the city of Copenhagen to nitrogen removal. The design chosen is based on the alternating mode of operation. Nitrification rates have been determined in batch tests on activated sludge extracted from the pilot plants and through the measuring of transient concentrations during the alternating mode of operation in the aerobic reactor. The data have been nonnalised to standard conditions by correcting them according to the kinetic theory. By monitoring the normalised nitrification rate it could be established that the nitrification process was occasionally inhibited. The aerobic sludge age required to maintain nitrification has been estimated. A specific evaluation has been made of the sensitivity of the required sludge age to the oxygen concentration and temperature.

Download Full-text

A flux-based stoichiometric model of enhanced biological phosphorus removal metabolism

Water Science & Technology ◽

10.2166/wst.1998.0727 ◽

1998 ◽

Vol 37 (4-5) ◽

pp. 609-613

Author(s):

J. Pramanik ◽

P. L. Trelstad ◽

J. D. Keasling

Keyword(s):

Phosphorus Removal ◽

Reaction Network ◽

Bacterial Biomass ◽

Enhanced Biological Phosphorus Removal ◽

Biological Phosphorus Removal ◽

Stoichiometric Model ◽

Aerobic Reactor ◽

Complete Set ◽

Biological Phosphorus

Enhanced biological phosphorus removal (EBPR) in wastewater treatment involves metabolic cycling through the biopolymers polyphosphate (polyP), polyhydroxybutyrate (PHB), and glycogen. This cycling is induced through treatment systems that alternate between carbon-rich anaerobic and carbon-poor aerobic reactor basins. While the appearance and disappearance of these biopolymers has been documented, the intracellular pressures that regulate their synthesis and degradation are not well understood. Current models of the EBPR process have examined a limited number of metabolic pathways that are frequently lumped into an even smaller number of “reactions.” This work, on the other hand, uses a stoichiometric model that contains a complete set of the pathways involved in bacterial biomass synthesis and energy production to examine EBPR metabolism. Using the stoichiometric model we were able to analyze the role of EBPR metabolism within the larger context of total cellular metabolism, as well as predict the flux distribution of carbon and energy fluxes throughout the total reaction network. The model was able to predict the consumption of PHB, the degradation of polyP, the uptake of acetate and the release of Pi. It demonstrated the relationship between acetate uptake and Pi release, and the effect of pH on this relationship. The model also allowed analysis of growth metabolism with respect to EBPR.

Download Full-text

Wastewater treatment and nutrient removal in the combined reactor

Water Science & Technology ◽

10.2166/wst.1998.0023 ◽

1998 ◽

Vol 38 (1) ◽

pp. 87-95 ◽

Cited By ~ 2

Author(s):

M. Roš ◽

J. Vrtovšek

Keyword(s):

Organic Compounds ◽

Industrial Wastewater ◽

Design Procedure ◽

Order Reaction ◽

Treated Wastewater ◽

Nitrification Rate ◽

Zero Order Reaction ◽

Aerobic Reactor ◽

Complex Organic

A combined anaerobic anoxic aerobic reactor for the treatment of the industrial wastewater that contains nitrogen and complex organic compounds as well as its design procedure is presented. The purpose of our experiments was to find a simple methodology that would provide combined reactor design. The reactor is based on the combination of anaerobic, anoxic and aerobic process in one unit only. It was found that the HRT even under 1 hour in the anaerobic zone is long enough for the efficient transformation of complex organic compounds into readily biodegradable COD which is then used in dentrification process. In the N-NO3 concentration range 1.5-50 mg/l the denitrification rate could be expressed as half-order reaction when the CODrb was in excess. N-NO3 removal efficiency is controlled by the recycle flow from the aerobic to the anoxic zone. Nitrification rate can be expressed as first, half or zero-order reaction with respect to effluent N-NH4 concentration. Nitrification rate depends on the dissolved oxygen concentration and hydrodynamic conditions in the reactor. Case study for design of a pilot plant of the combined reactor for treatment of pre-treated pharmaceutical wastewater is shown. Characteristics of pre-treated wastewater were: COD=200 mg/l, BOD5=20 mg/l, N-Kjeldahl=80 mg/l, N-NH4=70 mg/l, N-NOx<1 mg/l, P-PO4=5 mg/l. Legal requirements for treated wastewater were: COD=<100 mg/l, BOD5<5 mg/l, N-NH4=<1 mg/l, N-NOx=<10 mg/l.

Download Full-text

Denitrification in a Carbon and Nitrogen Removal System for Leachate Treatment: Performance of a Upflow Sludge Blanket (USB) Reactor

Water Science & Technology ◽

10.2166/wst.1999.0407 ◽

1999 ◽

Vol 40 (8) ◽

pp. 145-151 ◽

Cited By ~ 11

Author(s):

Liliana Borzacconi ◽

Gisela Ottonello ◽

Elena Castelló ◽

Heber Pelaez ◽

Augusto Gazzola ◽

...

Keyword(s):

Complete System ◽

Carbon Sources ◽

Uasb Reactor ◽

Leachate Treatment ◽

N Removal ◽

Start Up ◽

Aerobic Reactor ◽

C And N ◽

Reactor Operating ◽

Removal System

The performance of a bench scale upflow sludge bed (USB) denitrifying reactor was evaluated in order to integrate it into a C and N removal system for Sanitary Landfill Leachate. The raw leachate used presented COD and NH4-N average values of 30000 mg/l and 1000 mg/l, respectively. The complete system comprises in addition an UASB reactor and a nitrifying RBC. A portion of the aerobic reactor effluent was recycled into the denitrification stage and some raw leachate was also added as an additional C source. In order to obtain operating parameters the denitrifying reactor was operated alone. Sludge from an aerobic reactor (RBC) treating raw leachate was used as inoculum. Shortly after the start up, good granulation of the sludge bed was observed. Using raw leachate and UASB outlet as carbon sources with COD/NO3-N ratios of 4 and 12, respectively, denitrification efficiencies of about 90% were reached. A sludge yield of 0.16 gVSS/gCODremoved was obtained operating with raw leachate. For the anoxic reactor operating in the complete system, denitrification efficiencies of 90% were also achieved. A nitrogen gas recycle was a successful way to avoid frequently observed sludge bed rising problems.

Download Full-text

Application of Biofilm Carrier in Aerobic Reactors as a Method to Improve Quality of Wastewater Treatment

Hydrology ◽

10.3390/hydrology8020077 ◽

2021 ◽

Vol 8 (2) ◽

pp. 77

Author(s):

Nikolay Makisha

Keyword(s):

Ammonia Nitrogen ◽

Filling Ratio ◽

Treatment Quality ◽

Secondary Treatment ◽

Biofilm Carrier ◽

Aerobic Reactor ◽

Biofilm Carriers ◽

Optimal Efficiency ◽

Positive Results

The research revealed in the paper considers the improvement of secondary treatment of wastewater in the aerobic reactor to provide removal of organics and nutrients. There were five types of polymer biofilm carriers taken into account initially; however, two of them were decided not to apply due to technological reasons. The main part of the research was divided into three substages to investigate each type of biofilm carrier. According to the literature review, the optimal efficiency may be reached if the carrier filling ratio is 10 to 30% of reactor volume. On this basis, there were three benches launched at each sub-stage with a corresponding filling ratio of 10, 20, and 30%. The fourth reactor at each sub-stage had no floating carrier to control the experiment. The research of all three types of carriers showed the effect of BOD removal in the range of 95–96% for benches equipped with a floating carrier, which can be considered similar to the control bench with the efficiency of 92%. In the case of ammonia nitrogen, the removal control bench showed only 55% of efficiency, while floating carriers helped to increase the efficiency up to 70–86%. Despite obtaining relatively positive results, the research has to be continued to achieve regulation requirements in treatment quality.

Download Full-text