Loading...

07 June 2021

Industrial wastewater treatment applying high efficiency biological process FBR

Category:

1. Introduction: FBR biological wastewater treatment system

The FBR Flotation Bio Reactor’ is a biological wastewater treatment system that allows the removal of contaminants in a continuous and compact way.

These systems are generally more efficient in terms of removal of organic compounds and other biodegradable pollutants, footprint, and sludge generation than conventional activated sludge systems.

An FBR system consists of the introduction of the pre-treated wastewater, generally by screening and elimination of fats and oils, in a biological aeration reactor, where the contaminants in the water are in contact with microorganisms that degrade them in the presence of oxygen.

Oxygen is introduced into the reaction medium through aeration systems: fine bubble diffusers, coarse bubble diffusers, JET systems, etc. The control of the oxygen concentration and temperature within the reactor is key to provide the microorganisms with the optimal conditions in which they will carry out the elimination of contaminants.

Photo of a biological reactor designed and installed by SIGMA in the wastewater treatment plant of a dairy industry as part of an FBR process.
Biological reactor as part of an FBR process, designed and installed by SIGMA in a dairy industry.
Photo of the diffuser system of the biological reactor as part of the FBR process installed by SIGMA in the food processing industry.
Diffuser system inside the biological reactor as part of a FBR process, installed by SIGMA in a food processing industry.

As a consequence of the biological reactions carried out inside the reactor, the pollutants are transformed into carbon dioxide, water and cell growth of the biomass. A pump drives the sludge and treated water mixture to the subsequent clarification system.

The clarification system of a FBR is specially designed to separate the biomass from the treated water. A dissolved air flotation DAF unit is used to carry out this separation, generally assisted and optimized through the use of polyelectrolyte as flocculant agent.

By putting the sludge in contact with a polyelectrolyte in a flocculation equipment, the formation of biomass flocs is favoured, which will be easily separated in the DAF unit.

Clarification using DAF units allows a much higher concentration of separated sludge to be obtained than with conventional settlers, being able to reach a dry matter content of up to 5%.

Photo of a DAF as part of an FBR process, designed manufactured and installed by SIGMA in the wastewater treatment plant of a meat industry.
DAF unit designed and installed by SIGMA, this DAF is part of a FBR process applied to the treatment of wastewater from a meat industry.

Inside a DAF unit, air micro-bubbles are generated by pressurizing and saturating the recirculated clarified water stream with air. These bubbles, between 30-50 microns in diameter, adhere to the biomass flocs and rise to the surface of the DAF unit where they are separated by a skimmer system.

The settleable matter descends into the sediment compartment at the bottom of the DAF unit and is discharged by the sludge extraction system. The biological sludge is partly recirculated to the biological reactor and partly purged. Given that this sludge is highly concentrated, it is possible to reach very high biomass concentrations inside the reactor, which leads to greater efficiencies for the degradation of the contaminants in the wastewater.

DAF floated sludge collection system of the DAF unit part of the FBR process, designed and installed by SIGMA for the treatment of wastewater in a meat industry.
Floated sludge collection system of a DAF unit part of an FBR process installed by SIGMA for the treatment of wastewater in a meat industry.

In a SIGMA DAF flotation unit, perfectly clarified water is obtained that can be discharged complying with the discharge requirements. Part of the sludge will be recirculated to the biological reactor to maintain a stable biomass concentration and another part will be extracted as a purge for further management.

With FBR processes designed, built and installed by SIGMA, the discharge limits applied according to the type of industry can be efficiently reached.

2. Advantages of the FBR process

  • Continuous flow and quality of the clarified water effluent.
  • Very high reliability and process stability: the DAF systems are robust against variations in sludge quality.
  • FBR are generally compact systems and the size of the reactor is smaller than if a conventional activated sludge system of the same capacity was applied, since the biomass concentration achievable inside the reactor is much higher.
  • A DAF unit is smaller and involves fewer works and terrain modifications than a conventional settler.
  • The sludge obtained using a DAF system has a very high dry matter content, between 3 and 5%, much higher than that obtained in conventional settlers. The volume of sludge is therefore lower and represents savings in management costs and dewatering treatment.
  • They have great applicability in the industry: meat processing and slaughterhouses, vegetal food processing, fish processing, dairy, juice and sugary drink producers, pastry and bakery, textiles and tannery, oils and chemicals, pharmaceuticals, etc.

3. SIGMA Case Studies in industrial wastewater treatment with FBR processes

We share a collection of some Case Studies in the treatment of industrial wastewater with the FBR process designed, built and installed by SIGMA in various industrial sectors.

3.1 Biological treatment FBR in the malt processing industry

Photo wastewater treatment plant in a malt processing industry, whose water treatment plant uses an FBR system.

Year: 2011

Project locationCargill facilities in Villaverde, Madrid.

Objetives: · Meeting the discharge limits by law.

· Possibility of adaptation to the future necessities and production process expansion.

Installed technologies: a screening and homogenization system; a biological aerated reactor with JET aeration systems and nutrients dosing system; a coagulation-flocculation system SIGMA PLF with polyelectrolyte dosing system; a FBR clarification system SIGMA DAF FPAC-120; full sludge treatment with thickening tank and centrifuge decanter.  Instrumentation, control systems, and automation of the entire process.

Capacity: 1000 m3/day.

 

Wastewater characteristics

COD

BOD5

TKN

Total P

4000 mg/L

2000 mg/L

100 mg/L

20 mg/L

 

Efficiency

COD removal

BOD5 removal

TKN removal

Total P removal

> 75%

> 75%

> 50%

> 50%

Background

Cargill is a world leader in the production of food, agricultural products and services. Within the food sector, malt processing is one of its specialties. The malt processing industry uses large amounts of water for washing and processing both its intermediate and final products, which allows it to obtain optimal qualities. These water is characterized by high biodegradability, which allows applying biological treatments with very high efficiencies.

SIGMA designs and installs a FBR process ('flotation bio-reactor') consisting of an aeration reactor where biological treatment is carried out (this biological process consists of the transformation of the organic matter contained in the wastewater into microbial flocs by adsorption and agglomeration) and a separation of the biomass by flocculation and secondary clarification by DAF flotation (in this process biomass flocs are formed that will be separated by flotation with air micro-bubbles in a DAF FPAC-120 equipment. With these special equipment, sludge with a dry solids content 3 or 4 times higher than any conventional system is achieved)

In the SIGMA DAF flotation equipment, perfectly clarified water is obtained that can be discharged in compliance with the discharge requirements and a sludge that will be partly recirculated to the biological reactor to maintain a stable biomass concentration and partly extracted as a purge. The addition of polyelectrolyte to the clarification system allows the generation of easily separable biomass flocs in addition to providing a high concentration of biomass inside the reactor and therefore a higher performance than in other biological systems of suspended biomass.

In addition, SIGMA designs and installs the treatment of sludge generated by dewatering and decantation using a centrifuge.

Process diagram:

Diagram of the water treatment process in a malt processing industry using FBR water treatment.

Download case study

3.2. Biological treatment FBR in the dairy industry

Photo of the reactor in the wastewater treatment plant of the ice cream company: HELADOS ESTIU S.A. located in Ribarroja, Valencia.

Year: 2009

Project locationfacilities of HELADOS ESTIU S.A. in Ribarroja, Valencia.

Objetives:  · Removal of organic load from the pre-treated wastewater for the subsequent discharge of the effluent to the water collector.

· Adaptation to future needs and expansion of the facility.

Installed technologies: aeration tank for biological treatment; aeration system AQUAJET; coagulation-flocculation in-line system SIGMA PFL; flotation system SIGMA DAF FPAC-PWL; sludge thickening tank and sludge dewatering with centrifugal decanter; nutrients and chemicals dosing equipment; control and automation systems.

Capacity: 1000 m3/day.

 

Average organic load of the pre-treated wastewater

COD

BOD5

4500 mg/L

2500 mg/L

 

Efficiency of the full treatment

COD removal

Dry matter content of the treated sludge

90%

> 50%

Background

Helados ESTIU S.A. is a leader in the sector for the production of different types of ice cream. Its wastewater at the Ribarroja facilities contains a VERY HIGH MASS LOAD. The facilities already have a pre-treatment but the client also wants to install a biological treatment to eliminate the organic load required for discharge to the general collector.

SIGMA designs and installs a FBR process ('flotation bio-reactor') consisting of an aeration reactor where aerobic biological treatment is carried out (this biological process consists of the transformation of the organic matter contained in the wastewater into microbial flocs by adsorption and agglomeration) and a separation of the biomass by flocculation and secondary clarification by DAF flotation (in this process biomass flocs are formed and will be separated by flotation with air micro-bubbles in a DAF FPAC-PWL equipment. These special equipments obtain sludge with a dry solids content 3 or 4 times higher than any conventional system)

In the SIGMA DAF FPAC-PWL flotation equipment, perfectly clarified water is obtained that can be discharged meeting the discharge requirements and a sludge that will be partly recirculated to the biological reactor to maintain a stable biomass concentration and partly extracted as a purge. The addition of polyelectrolyte to the clarification system allows the generation of easily separable biomass flocs in addition to providing a high concentration of biomass inside the reactor and therefore a higher performance than in other biological systems of suspended biomass.

The SIGMA DAF FPAC-PWL flotation system is a modular system that is easy to expand and has a high capacity to adapt to different biomass concentrations.

SIGMA also installs a complete sludge treatment process: thickening and dewatering in a centrifugal decanter.

Process diagram

Photo of the biological reactor in the wastewater treatment plant of the company Helados Estiu S.A. located in Ribarroja, Valencia.

Download case study

3.3. Biological treatment FBR in the food processing industry

Picture of the wastewater treatment plant from the food processing industry where SIGMA's FBR biological treatment is applied.

 

Year: 2010

Project location: facilities of Tostaderos Sol de Alba S.A.

Objetives:  · Instalation of a biological treatment FBR and clarification after the existing pre-treatment to comply with the discharge limits.

Installed technologies: aeration tank for biological treatment; aeration-recirculation system MTJET for the biological reactor; clarification system SIGMA DAF FPAC-PWL-35;  nutrients and polyelectrolyte dosing equipment ; control and automation systems.

Capacity: 430 m3/day.

 

Characteristics of the pre-treated wastewater

COD

BOD5

Total Nitrogen

4000 mg/L

1000 mg/L

60 mg/L

 

Efficiency of the biological treatment FBR

COD removal

BOD5 removal

Total Nitrogen removal

> 60%

> 88%

> 56%

 

Background

At the facilities of Tostaderos Sol de Alba S.A. where the production of fried corn is carried out, there is a pre-treatment of the wastewater that is insufficient to meet the discharge requirements. A biological treatment with a FBR process is designed and installed to further treat the wastewater up to discharge limits.

SIGMA designs and installs a FBR process ('flotation bio-reactor') consisting of an aeration reactor where biological treatment is carried out (this biological process consists of the transformation of the organic matter contained in the wastewater into microbial flocs by adsorption and agglomeration) and a separation of the biomass by flocculation and secondary clarification by DAF flotation (in this process biomass flocs are formed that will be separated by flotation with air micro-bubbles in a DAF FPAC-PWL-35 equipment. With these special equipment, sludge with a dry solids content 3 or 4 times higher than any conventional system is achieved)

The SIGMA DAF FPAC-PWL flotation equipment is a cross flow separator designed to treat wastewater with a high solids load.

In the SIGMA DAF flotation equipment, perfectly clarified water is obtained that can be discharged in compliance with the discharge requirements and a sludge that will be partly recirculated to the biological reactor to maintain a stable biomass concentration and partly extracted as a purge. The addition of polyelectrolyte to the clarification system allows the generation of easily separable biomass flocs in addition to providing a high concentration of biomass inside the reactor and therefore a higher performance than in other biological systems of suspended biomass.

The SIGMA DAF FPAC-PWL flotation system is a modular system that is easy to expand and has a high capacity to adapt to different biomass concentrations.

 

Process diagram

Process diagram of a wastewater treatment process with the application of a biological FBR system in a processed food processing industry.

Download case study

3.4. Full treatment RANC + FBR in the food processing industry

Complete RANC + FBR treatment of wastewater from the food processing industry to meet discharge requirements.

Year: 2016

Project location: facilities of Congelados de Navarra in Fustiñana, Navarra

Objetives:  ·Installation of a complete treatment of wastewater from the vegetable processing units that allows compliance with the discharge requirements.

·Flexible and adaptable treatment to the high variability and temporality both in flow and organic load of wastewater.

Installed technologies: Pump systems, screening and sand separation; homogenization tank; anaerobic reactor SIGMA RANC; gas filter; clarifier SIGMA BIODAF-FPBC-PWF; aerobic reactor and aeration system; final clarifier SIGMA BIODAF 200-TWIN; in-line flocculation system SIGMA PFL; full sludge treatment via dewatering with centrifugal decanter. Control and automation systems.

Capacity: 1300 m3/day.

 

Wastewater characteristics for process design

COD

BOD5

TSS

TKN-N

15000 mg/L

8000 mg/L

2000 mg/L

175 mg/L

 

Treatment efficiency

COD removal

TSS removal

TKN-N removal

> 96%

> 97%

> 91%

Background

Congelados de Navarra S.A. is a leading company in its sector. Its activity is focused on the processing of vegetables for later freezing. The wastewater from the Fustiñana factory has a high load of biodegradable organic compounds, this is why a complete biological treatment plant is designed and installed to reach the discharge limits. Two biological processes are installed in series: an anaerobic digestion with a SIGMA RANC reactor and an aerobic SIGMA FBR treatment. The plant also includes a gas filtering line and a complete sludge treatment. Given the seasonality of vegetable production, the plant is robust but flexible and can adapt to changes in production both in flow and in the nature of the water (from the processing of very different vegetables: cauliflower, broccoli, rice, potatoes, peas, etc. carrots, etc).

The SIGMA RANC anaerobic digestion process consists of a contact up flow reactor, where the removal of organic compounds is carried out under anaerobic conditions, transforming COD and BOD5 mainly into biogas and very little sludge generation. The anaerobic sludge is separated by flotation clarification in a SIGMA BIODAF-FPBC-PWF system. The biogas generated is treated in a filter to remove hydrogen sulphide.

The FBR process (‘flotation bio-reactor’) consists of an aeration reactor where biological treatment is carried out in the presence of oxygen. This biological process consists of the transformation of the organic matter that was not eliminated in the anaerobic reactor, in it microbial flocs are generated by adsorption and agglomeration. These biomass flocs are separated by coagulation, flocculation and secondary clarification by DAF flotation: in this process biomass flocs are formed that will be separated by flotation with air micro-bubbles in a SIGMA BIODAF 200-TWIN equipment.

The flotation clarification equipments SIGMA BIODAF are special equipments that present greater reliability against spongy sludge with low sedimentation rate, such as those typically generated in the treatment of industrial wastewater.

The sludge generated in both clarifications is treated jointly by dewatering with a centrifugal decanter equipment.

Process diagram

Diagram of the complete process of RANC and FBR wastewater treatment in a food processing industry.

Download case study

3.5. Installation of a DAF clarifier as part of a FBR process in the meat industry

Photo of a DAF clarification system model FPAC 160/200 as part of an FBR process in the treatment of wastewater in a meat industry.

Year: 2019

Project location: facilities of Congelados de Navarra in Fustiñana, Navarra

Objetives:  ·Installation of a complete treatment of wastewater from the vegetable processing units that allows compliance with the discharge requirements.

·Flexible and adaptable treatment to the high variability and temporality both in flow and organic load of wastewater.

Installed technologies: in-line coagulation-flocculation system SIGMA PFL-180; clarification via dissolved air flotation SIGMA DAF FPAC160/200.

Capacity: 200 m3/day.

 

Wastewater characteristics for process design

TSS

Oil and fat

4500 mg/L

500 mg/L

 

Clarification efficiency

TSS removal

Oil and fat removal

90%

90%

 

Background

Cárnicas Medina is a leading company in the meat sector. Its facilities in Valencia have a wastewater treatment plant through biological treatment and require the installation of secondary clarification forming a FBR process.

The FBR process (‘flotation bio-reactor’) consists of an existing biological reactor in the plant where the elimination of organic matter is carried out, in its microbial flocs are generated by adsorption and agglomeration. These biomass flocs are separated by a combined coagulation-flocculation process followed by clarification.

Coagulation-flocculation is carried out in a SIGMA PFL-180 equipment in which coagulant is incorporated to group the generated biomass and flocculant (polyelectrolyte) to agglomerate these biomass aggregates into larger flocs.

The clarification with dissolved air flotation DAF allows the separation of the flocs formed, by means of air micro-bubbles dissolved in a SIGMA DAF FPAC160/200 equipment.

DAF systems are introduced to separate oils, greases, fats, solids and flocs that do not have enough buoyancy to float, or when a mixture of emulsified fats, oils and solids affect the specific gravity in such a way that the flotation air is necessary to improve the separation, they are also applied in FBR processes for the separation of biomass flocs. The size of the air bubbles is between 30 and 50 microns, which is key for the flotation system as the micro bubbles easily adhere to particles of the same size or greater.

SIGMA DAF flotation clarification equipment are special equipment highly reliable and robust, as well as flexible, allowing it to be adapted to possible fluctuations in wastewater emissions and plant operation.

Process diagram

Diagram of a wastewater treatment process in a meat industry, where a DAF is part of an FBR system for water treatment.

Download case study

3.6. Complete wastewater treatment using a FBR process in a meat industry

SIGMA BIODAF FPAC 50 system for the complete treatment of wastewater from the meat industry by means of a biological FBR system.

Year: 2018

Project location: Slaughterhouse of the company Vall d’en Bas, in Sant Privat d’en Bas, Girona.

Objetives: · Compliance with current discharge requirements.

· Adaptation to possible future modifications of the slaughterhouse.

Installed technologies: Large solids screening; solids, oil and fats separator SIGMA ACAF-025; anoxic-aerobic reactor with diffusers; in-line flocculation system SIGMA PFL-020; secondary flotation clarifier SIGMA BIODAF FPAC 50. Sludge treatment with thickening tank and centrifugal decanter. Control and automation systems.

Capacity: 150 m3/day.

 

Wastewater characteristics

COD

TKN

NH4+

TSS

Oils and fats

6000 mg/L

500 mg/L

175 mg/L

2000 mg/L

500 mg/L

 

Treatment removal efficiency

COD

TKN

NH4+

TSS

Oils and fats

> 75%

> 82%

> 65%

> 85%

> 96%

Background

 

Cárniques Vall d'en Bas is a leading company in the meat sector. It has facilities for its beef slaughterhouse that requires a complete treatment for wastewater. The main objective is compliance with the discharge limits for the discharge of treated water.

A pre-treatment consisting of a sieving system followed by a SIGMA ACAF-25 induced air cavitation flotation primary clarifier is installed. In this pre-treatment, the removal of larger solids, oils and fats takes place. The FBR biological treatment is installed after the pre-treatment.

The FBR process (‘flotation bio-reactor’) consists of an anoxic-aerobic reactor with prolonged aeration of activated sludge where biological treatment is carried out in the presence of oxygen. This biological process consists of the elimination of organic matter through biological reactions with biomass. Microbial flocs are generated by adsorption and agglomeration. These biomass flocs are separated by flocculation and secondary clarification by DAF flotation.

The flocculation is carried out in a SIGMA PFL-020 equipment in which flocculant is incorporated as polyelectrolyte to flocculate the generated biomass agglomerates.

The secondary clarification with dissolved air flotation DAF allows the separation of the flocs formed, with dissolved air micro-bubbles. The biomass flocs are separated by flotation with air micro-bubbles in a SIGMA BIODAF FPAC-50 equipment.

The flotation clarification equipment SIGMA BIODAF are special equipment that present greater reliability against spongy sludge with low sedimentation rate, such as those typically generated in the treatment of industrial wastewater.

The sludge generated in both clarifications is treated jointly by thickening and dewatering with a centrifugal decanter. Dewatered sludge of 20% in dry matter is obtained.

Process diagram

Diagram of the complete treatment process of wastewater from the meat industry using a biological system of the FBR type.

Download case study