Upflow Sludge Blanket Filtration (USBF) process is improved from the combination among classically active mud and anoxic process and the area of hanging over deposit mud in a biological process project. It is a collaboration system so that it occupies not much area and attached equipment. USBF process is designed for:
- Carbonate organic substance deoxidizing
- BOD deoxidizing, nitrification and nitrate deoxidizing
- BOD deoxidizing, nitrification/nitrate deoxidizing and phosphorus deoxidizing
To deoxidize carbonate, anoxic is viewed as the selecting zone in which the mix of emission lines will increase the ability of deposit and limit the process of bacteria grow-up.
Anoxic zone can be in charge with nitrification, nitrate deoxidizing and phosphorus deoxidizing. Within it, NH3-N is oxygenated to nitrite and after that being nitrate by nitrosomonas bacteria and nitrobacteria in each private air zone. Nitrate comes back circularly in anoxic zone and is deoxidized continually. In this reaction, input BOD is considered as carbon source or energy source to deoxidize nitrate to nitro molecule.
Mechanically phosphorus deoxidization is like to phosphorus cycle and innovated from Bardenpho process. In USBF, the fermentation of BOD occurs in anti-air zone or anoxic zone. The product of fermentation process creates an important part of microorganisms which can store phosphorus. In phase of aerobic treatment, dissolved phosphorus is absorbed by phosphorus storing in Acinetabacter that grows up from anoxic zone. Anabolic phosphorus is got away from the system like microorganism rubbish or redundant mud. The mass and content of ejected phosphorus depends mostly on BOD/P ratio into input drain water.
USBF process can deoxidize BOD5 down to under 5 mg/l, TSS under 10mg/l without filter section, nitro under 1mg/l and phosphorus from 0.5 to 2 mg/l. The special deoxidization process of phosphorus can be implemented by adding metal salt in aerobic zone at the time of waste effluent comes to accumulation zone. Kinds of salt can be used such as aluminum salt (Al2(SO4)3.14H2O), Aluminate natri (Na2O.Al2O3), chloral iron (FeCl3), (FeCl2), sulfate iron (FeSO4.&H2O) or sulfate tri-iron (Fe2(SO4)3). When almost phosphorus in USBF process (>80%) is absorbed by biological method, one less content of assembling salt iron is brought to the system that cannot arise waste mud. For example, deoxidizing phosphorus by FeSO4 due to 2 reactions
Phosphorus assembling
3FeSO4 + 2PO4-3 ---------> Fe3 (PO4)2 + 3SO4-2
Alkali deoxidization and hydroxide precipitation
Fe+++ + 3HCO-3 -----------> Fe(OH)3
Following the two above reactions, to remove 2 mg/l PO4-3 , there is 6 mg/l mud theoretically. 5 mg/ mud can deoxidize 1 mg/l PO4-3 . To the input waste water, there has 240 mg/l BOD and the speed of growing mud is 0.6 lbs TSS/lb deoxidizing and using FeSO4 for 2 mg/l PO4-3 .The total amount of producing mud is about 7%.
USBF process is created by the principle of depositing line in tub to have upflow sludge blanket clarifier. It has the shape of trapezium and drain water after disordering will go from the bottom through special designed walls in which happens producing process of hydraulic cotton. Trapezium accumulation tub creates the speed for rising consistent water lines all the surfaces from bottom to the upper of tub. This helps to reduce gradient and velocity in accumulation tub.
USBF advantages
1. Reduce investment cost
USBF combines all treatment processes into one tub to reduce the dimension tubs and the project investment cost.
2. Low costs of operation and maintenance
With tidy design, minimizing engines, mobile equipment and operating by automatic run mode, it will limit the process supervision and prevent at most operation and maintenance costs
3. High treatment productivity
It is the technology designing for deoxidizing organic substances (BOD, COD) and nutritional substance (N,P) so that drain water quality after processing always guarantees the elimination standard that other biological treatment projects cannot solve (content of nutritional substances).
The concentration of BOD5 and TSS is less than 10 mg/l and N-NH3 under 0.5 mg/l after process. USBF deals with carbon organic substances, nitro and phosphorus
4. Small reducing waste mud
The system is designed with 25 day old mud so that the quantity of producing mud is less than with the normal biological aerobic system
5. Reducing smell
Under the condition of aerobic disintegration and high sludge concentration, it reduces factors to create smell. USBF tub can be installed at high population zones that do not care much by smell.
6. Flexible volume change
Cone-shaped accumulation tub in the empty tub creates different reactions around and it can change itself volume flexibly, which affects much to the volume of the rest stages. Also, USBF tub can bear the over discharging. When the flow increases fast, active mud layer with be high and create a larger filter area so that it only affect less to quality of output water.
7. Union design
Because combining many processes in a project, so USBF likes a complete design project. Besides that, it has the rectangular shape, therefore, it so easy to design in unit. Unionizing helps design work be more flexible on space and system capacity. Based on simple shape, it can design BF technology to improve old projects or installed in predefined area.
8. Increase the ability to dry mud
Increasing years of mud in the system will improve mechanical structure to make drying mud process faster.
9. No need of accumulation tub on turn 1
USBF technology often does not need turn 1 tub ahead. To the big systems, there is only a rubbish floor system, and salt to ensure for biological processing demand.
10. Save used space
USBF technology combines all processes of nitrate deoxidization, nitrification, accumulation in a project to decrease the whole dimensions of project, which leads to less used space.
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