WO2012158013A1

WO2012158013A1 - Anaerobic treatment of organic wastewater

Info

Publication number: WO2012158013A1
Application number: PCT/MY2011/000045
Authority: WO
Inventors: Zhen Jia ZHANG
Original assignee: Ronser Bio-Tech Sdn Bhd
Priority date: 2011-05-13
Filing date: 2011-05-13
Publication date: 2012-11-22
Also published as: AU2011368431A1; MY175227A; BR112012000084A2

Abstract

Anaerobic treatment of organic wastewater is the technology that related to wastewater treatment technologies field. This invention constitute of a tower vessel and a built-in water distributor, three-phase separator and a consistent gas hydraulic pressure balancer as well as fire barrier, and accumulation zone of acidogenic bacteria and methanogenic bacteria on the top of water distributor. Processing water flow rises in a uniform distribution when passing the cross section pf water distributor, organic matters are converted to methane and carbon dioxide gas while passing by acidogenic arid methanogenic bacteria accumulation zone, then treated water and gas are transferred out by three-phase separator and gas hydraulic pressure balancer as well as fire barrier. Anaerobic bacteria sludge is retained within the device effectively without any loss. Also, this invention doesn't require the set up of hydrolysis acidification pool and water backflow, which keep the process simple and easy, able to operate stably at 1-30kgCOD/m³.d with organic matter removal rate of 90%.

Description

ANAEROBIC TREATMENT OF ORGANIC WASTEWATER

FIELD OF INVENTION

Anaerobic treatment of organic wastewater is a present invention related to wastewater purification system. It does not require the set up of acid hydrolysis pool, or the water backflow method.

BACKGROUND ART

In recent years, anaerobic treatment has developed as an energy-efficient and methane producing technology in organic wastewater treatment technologies field, which is one of the most spectacular technology. Anaerobic technology is the core of both anaerobic bacteria to be able to be optimized for high-density reproduction to form a stable eco-system of anaerobic metabolism, but also to keep treatment plant simple and easy to implement.

Under the guidance of the above objectives, existing anaerobic treatment technologies include completely mixed anaerobic treatment, anaerobic filter bed process, up-flow anaerobic sludge blanket processing (UASB) and expanded granular sludge bed anaerobic treatment (EGSB). Among them, UASB and EGSB have been developed as the most representative technology in nearly three decades. The common characteristic between these devices is the use of granular anaerobic bacteria (commonly known as: soil particles), which could maximize the cell concentration and a clear separation of solid-liquid; whereas the different is the level degree of the sludge bed expansion by these soil particles. UASB has low expansion degree, whereas EGSB has greater degree of expansion.

However, there are four major problems need to be concerned:

1. Diversity of ancillary facilities, complexity of the processes. For existing UASB and EGSB, a pre-treatment of hydrolysis acidification poo! set up is required for the treatment plant. The main purpose of the poo! is to convert organic matter in wastewater to acetic acid based organic matter, through anaerobic hydrolysis acidification bacteria. So that anaerobic bacteria, in anaerobic treatment plant, can only use the acetic acid based organic matter for methane-producing metabolic reactions. Therefore, only degradation of acetic acid based matter system is formed in the devices to produce methane. Due to the. sensitivity of these bacteria toward pH and temperature change, also the suppression of matrix when the concentration is over 5000mg/LCOD, it is a necessary to adopt a more complex and stringent method to manage water quality control devices, which cause an increase in processing cost.

Besides, an odour gas is produced as a side product during the hydrolysis acidification of wastewater process, which brings pollution to environment. To eliminate the odour gas, odour elimination facilities are required which therefore result in increasing of operating cost.

Complexity of the treatment plant. Present UASB and EGSB technologies adopt the "three-phase separator" that make up of a number of triangular cross-section of the folded plate posed by three dimensional arrays, and water conduction that involved the mixture of treated flow back water and processed water. This could help to mix processed water with anaerobic bacteria within device completely, to prevent a deadend and short of water flow, also, able to deliver treated water and methane gas out of the device separately and smoothly without losing anaerobic bacteria. In addition, to ensure processed water mix completely with flow back water, a water distributor that constitute of cross-section shape of triangle is used as well. Flow back of processed water riot only complicates the ancillary facilities, but also decrease the concentration of matrix. Therefore, causing the cost of processing system and operation increased, but not the rate of biological reactions. Besides, this triangular cross-section folded plate of the separator requires sWct geometry measurement and specific arrangement while installing in the internal volume of the device. It occupies 1/3 space of the device, therefore complicates the mechanical structure and increases the cost.

A granular sludge must be used to be inocula. In most cases, it is relatively difficult and expensive to look for a suitable anaerobic sludge treatment plant as the seed sludge. As the existing UASB and EGSB require granular sludge to begin, this could limit the application of the technology and restrict the expansion of the market. Suitable only for high volume ( ad. This is becaus while running under low load, UASB and EGSB will result in the disintegration of granular sludge with the Water outflow. However, in dealing with high concentration of organic wastewater, the high volume load will cause high concentrations of residual organic matter remain in treated water, that could increase the difficulty of achieving standard level at the follow-up aerobic treatment and cost of compliance. Also, in most cases, anaerobic treatment plant is not able to operate under high load due to wastewater characteristic, result in the difficulty and limitation of the application,

SUMMARY OF INVENTION

The purposes of this invention is to overcome the deficiency of existing technologies, provide a method of anaerobic treatment of organic wastewater that is using a simplified treatment plant structure and operate procedures, without set up of hydrolysis acidification pool and water backflow.

To achieve the above objectives, this invention includes a towel vessel with a water distributor build within, a three-phase separator, a gas hydraulic pressure balancer also a hydraulic fire barrier constitution. Accumulation zone for aeidogenic bacteria and methanogenic bacteria are set above the water distributor respectively. Processing water flow rises in a uniform distribution when passing the cross section of water distributor, and organic matter is broken down to methane and carbon dioxide gas at accumulation zone of aeidogenic bacteria and methanogenic bacteria, then passes the three-phase separator and gas hydraulic pressure balancer as Well as fire barrier. Thus, water and gas are able to be discharged separately, whereas anaerobic sludge is retained effectively in the device without any loss.

Procedures of anaerobic treatment of organic wastewater are shown below:

1 ) The treatment plant is a tower vessel with a steel cylindrical covering, one or more vertical cylindrical three-phase separator is distributed uniformly at the top of the tower vessel, a hexagonal or octagonal-shaped grille water distributor that has an identical diameter with the tower vessel is installed at the bottom of the vessel. Gas hydraulic pressure balancer as well as fire barrier is arranged on the top of the gas discharge tube at the top Of the vessel in series. Water inlet pipe is connected to the water distributor; outlet pipe is connected to three-phase separator. Total height of the tower vessel is 2-25m, a diameter of 0.5-20meter. 2) Accumulation zone for aeidogenic bacteria and methanogenic bacteria is separated in proper order on the top of the water distributor. The content of aeidogenic anaerobic bacteria and methanogenic anaerobic bacteria in respective zones is 10- 50g/L; where the total height for both accumulation zones is 0.7-0.8 times the tower height, and the ratio of height of aeidogenic bacteria accumulation zone to methanogenic bacteria accumulation zone is 1 :1.8-2. 3) Water inlet pump delivers wastewater at a stable flow rate of 60-400m³/hour from inlet pipe to tower vessel, where processing water flow rises in a uniform distribution when passing the cross section of water distributor.

4) Water flow is rose and passed the acidogenic bacteria accumulation zone on the top of water distributor, fully contacted with bacteria where ail the organic matter is converted to volatile acetic acid based organic acids.

5) Treated water flow is continued to rise and passed the methanogenic bacteria accumulation zone, again fully contacted with bacteria. Volatile organic acids are converted to methane gas in this process, so that organic matter in water is eliminated.

6) After methanogenic process, treated water flow is rose and passed three-phase separator, treated water is delivered out of the tower vessel through Outlet pipe, whereas methane gas is transferred by gas hydraulic pressure balancer as well as fire barrier to methane facilities (such as boiler and internal combustion engine). The whole anaerobic process is started where water flow from the bottom of the tower vessel, rose up to three-phase separator, and completed at the outlet pipe of the separator.

This invention allows non-granular anaerobic bacteria sludge to be used for the initiation, and able to reach the stable operation state while granular sludge is not formed.

Also, this invention is a simple and easy method. It does not require the set up of hydrolysis acidification pool, water back flow process and complicated operating procedures. Organic matter of wastewater can be converted to organic acids then to methane gas completely in just one treatment plant. Acidogenic fermentation bacteria and methanogenic fermentation bacteria are kept separately while enable the fermentation to happen at the same time, result in a stable and ideal treatment plant. This invention can be operated stably at 1-30kgCOD/m³.d, where the organic matter in wastewater is eliminated at removal rate of 90%.

BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS

Figure 1 is the schematic drawing of the treating plant structure related to the invention. In Figure 1, 1 is the inlet pipe, 2 Is the ¾eidogenic bacteria a∞umulation zone, 3 is the methanogenic bacteria accumulation zone, 4 is the outlet pipe, 5 is the methane gas discharge tube, 10 is the tower vessel, 11 is the water distributor, 12 is the three-phase separator, 13 is the gas hydraulic pressure balancer as well as the fire barrier.

Figure 2 is the vertical view of three-phase separator in the treatment plant. In Figure 2, 2 is the three-phase separator.

Figure 3 is the vertical view of water distributor.

In Figure 3, 11 is the water distributor.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Further description is shown below, followed by an attached and case study. The protection of the invention does not limit the implementation.

Figure 1 is the structure diagram of this treatment plant. As shown in Figure 1 , a cover of the treatment plant 10, is a steel cylindrical covering of the tower vessel, one or more vertical cylindrical three-phase separator 12 uniformly distributed o the top of the tower vessel, a hexagonal or octagonal-shaped grille water distributor that has an identical diameter with the tower vessel is installed at the bottom of the vessel 11 , gas hydraulic pressure balancer as well as waterpower fire barrier 13 is arranged in series on methane gas discharge tube 5 at the top of tower vessel; inlet pipe 1 is connected to water distributor 11 , outlet pipe 4 is connected to three-phase separator 12. The height of the tower vessel is 2-25m, 0.5-20 m in diameter.

Accumulation zone for acidogenic bacteria 2 and methanogenic bacteria 3 is separated in proper order on the top of the water distributor 11. The content of acidogenic anaerobic bacteria and methanogenic anaerobic bacteria in respective zones is 10-5.0g L; where the total height for both accumulation zones is 0.7-0.8 times the tower height, and the ratio of height of acidogenic bacteria accumulation zone to methanogenic bacteria accumulation zone is 1 :1.8-2.

Figure 2 is the vertical view of three-phase separator in treatment plant. As shown in Figure 2, one or more vertical cylindrical three-phase separator 12 uniformly distributed on the top of tower vessel. In following example of the implementation of this invention, there are five vertical cylindrical three-phase separator been used, where the cylindrical diameter is 0;5 -3 meters, the height is 0.5-4 meters.

Figure 3 is the vertical view of water distributor. As shown in figure 3, cross section of water distributor 11 is hexagonal or octagonal- shaped grilles, which have an identical diameter as the tower vessel. Methods of anaerobic treatment of organic wastewater are shown below:

Water inlet pump 1 delivers wastewater at a stable flow rate of 60-400m³/hour (1/24 of daily wastewater) from inlet pipe to tower vessel, where processing water flow rises in a uniform distribution when passing the crpss section of water distributor 11.Water flow is rose within tower vessel 6 and passed the acidogenic bacteria accumulation zone 2 and methanogenic bacteria accumulation zone 3 accordingly.

Water flow is rose and passed acidogenic bacteria accumulation zone 2 at top of water distributor 11 , contacted fully with anaerobic bacteria. Organic matters are converted to acetic acid based volatile organic acid Completely while passing by. Treated water flow is then rose and passed methanogenic bacteria accumulation zone, which located above acidogenic bacteria accumulation zone, and contacted fully with anaerobic bacteria. Organic matters are eliminated while volatile organic acid is converted to methane gas.

After methanogenic bacteria accumulation zone, treated water flow is rose and passed three-phase separator 12, treated water is delivered out of the tower vessel through outlet pipe 4, whereas methane gas is transferred by gas hydraulic pressure balancer as well as fire barrier 13 to methane facilities (such as boiler and internal combustion engine). The whole anaerobic process is started where water flow from the bottom of the tower vessel, rose up to three-phase separator, and completed at the outlet pipe of the separator. In this treatment process, content of anaerobic is increased followed by extension time of processing. To keep the balance between sludge volume and processing load, surplus of anaerobic sludge need to be removed regularly.

Below are implementation examples of this invention. Implementation example 1

In this example, this invention is used to process wastewater from brewery. Volume of wastewater is 8000-10000m³/d; concentration of GOD is 1500-3500mg/L. In this process, two anaerobic reactors are used, where the diameter of 14m and height of 18m. Anaerobic digested and dehydrated excess sludge with moisture content of 70 % from domestic sewage treatment plant is used as inocula. After processing, concentration of COD in treated water is 150-200mg/L, which has achieved the COD removal rate of 90%.

Implementation example 2

In this example, the invention is used to process raw cassava ethanol wastewater, Volume of wastewater is 1500-2000m³/d; concentration of COD is 28000-35000mg/L. In this process, two reactors are used, where the diameter of 14m and height of 15m. Anaerobic digested and dehydrated excess sludge with moisture content of 70 % from domestic sewage treatment plant is used as sludge inocula. After processing, concentration of COD in treated water is around 1500mg/L, which has achieved the COD removal rate of 90%. Implementation example 3

In this example, the invention is used to process corn fuel ethanol wastewater. Volume of wastewater is 5000-8000m³/d; concentration of COD is 3000-6000mg/L. In this process, two anaerobic reactors are used, where the diameter of 15m and height of 18m. Anaerobic digested and dehydrated excess sludge with moisture content of 70 % from domestic sewage treatment plant is used as sludge inocula. After processing, concentration of COD in treated water is around 80-120mg/L, which has achieved the COD removal rate of 90%.

Claims

1. An anaerobic treatment of organic wastewater, characteristics of the treatment plant is due to following: a. The treatment plant is a tower vessel with a steel cylindrical covering (10), one or more vertical cylindrical three-phase separator(12) is distributed uniformly at the top of the tower vessel, a hexagonal or octagonal^shaped grille water distributor (11 ) that has an identical diameter with the tower vessel is installed at the bottom of the vessel. Gas hydraulic pressure balancer as well as fire barrier (13) is arranged on the top of the gas discharge tube (5) at the top of the vessel in series. Water inlet pipe (1 ) is connected to the water distributor (11 ); outlet pipe (4) is connected to three-phase separator (12). Total height of the tower vessel is 2-25m, a diameter of 0.5-20meter. b. Accumulation zone for acidogenic bacteria and methanogenic bacteria is separated in proper order on the top of the water distributor (11 ). The content of acidogenic anaerobic bacteria and methanogenic anaerobic bacteria in respective zones is 10-50g/L; where the total height for both accumulation zones is 0.7-0.8 times the tower height, and the ratio of height of acidogenic bacteria accumulation zone to methanogenic bacteria accumulation zone is 1 :1.8-2. c. Water inlet pump delivers wastewater at a stable flow rate of 60-400m³/hour from inlet pipe (1) to tower vessel, where processing water flow rises in a uniform distribution when passing the cross section of water distributor (11 ). d. Water flow is rose and passed the acidogenic bacteria accumulation zone on the top of water distributor (11 ), fully contacted with bacteria where all the organic matter is converted to acetic acid based volatile organic acids. e. Treated water flow is continued to rise and passed the methanogenic bacteria accumulation zone, again fully contacted with bacteria. Volatile organic acids are converted to methane gas in this process, so that organic matter in water is eliminated. f. After methanogenic bacteria accumulation zone, treated water flow is rose and passed three-phase separator (12), treated water is delivered out of the tower vessel through outlet pipe (4), whereas methane gas is transferred by gas hydraulic pressure balancer as well as fire barrier (13) to methane facilities (such as boiler and internal combustion engine). The whole anaerobic process is started where water flow from the bottom of the tower vessel, rose up to three-phase separator, and completed at the outlet pipe of the separator.

2. In accordance with claim 1 , a cylindrical tower vessel in a diameter of 0.5-20 m and height of 2-25 m are characteristics of anaerobic treatment of organic wastewater.

3. In accordance with claim 1 , a three-phase separator in diameter of 0.5-3 m and height of 0.5-4 m are characteristics of anaerobic treatment of organic wastewater.

4. In accordance with claim %, a granular or flocculent of acidogenic or methanogeriie anaerobic bacteria are characteristics of anaerobic treatment of organic wastewater;