The advantages and disadvantages of SBR technology.

Date public: 17-06-2024||View: 825

Nowaday, industrial wastewater treatment is a crucial issue for environmental safety due to the enormous amount of wastewater discharged by industries. Many companies either do not build proper wastewater treatment systems or construct inadequate ones, leading to severe water pollution. So, what is the SBR treatment technology? Let’s explore some information about SBR technology with Đại Nam.

1. What is SBR Treatment Technology?

SBR stands for Sequencing Batch Reactor, which is a technology used for treating domestic wastewater through a biological reaction process in a continuous batch sequence. This is considered one of the most effective wastewater treatment solutions.
The SBR wastewater treatment technology consists of two main tank clusters: the Selector tank cluster and the C-tech tank cluster. According to the working principle, wastewater is first directed into the Selector tank, and after preliminary treatment, it is transferred to the C-tech tank.
The SBR tank operates in a cyclical sequence of 5 phases: filling, aeration, settling, decanting, and idle. These processes are carried out continuously.
With scientifically calculated SBR tanks, this type of tank provides optimal efficiency for production facilities.

2. Explanation of the SBR Technology Process

2.1 Collection Pit

Wastewater from factories in industrial zones is collected and passed through a grit chamber combined with a coarse screen. Large debris is separated, and sand settles at the bottom of the chamber, to be removed periodically. The wastewater continues to flow into the collection pit of the industrial wastewater treatment system.
At the collection pit, the wastewater is automatically pumped through a fine screen. The fine screen removes smaller debris before the wastewater enters the oil separator. In the oil separator, oils and fats present in the wastewater are removed and collected in a grease tank for disposal. Next, the wastewater flows into the equalization tank, where it is equalized in terms of flow, with the help of two submerged mixers, and the pH of the wastewater is adjusted using H2SO4 and NaOH solutions before entering the reaction tank.

2.2 Reaction Tank

Next, the wastewater is pumped into the reaction tank. In this tank, a coagulant solution is added, combined with mixing to promote floc formation, which facilitates the settling process in the settling tank. The wastewater then flows into the settling tank, where the sludge flocs settle at the bottom. Periodically, this sludge is pumped to the sludge storage tank, and the clarified water flows to the SBR aerobic biological tank. In this tank, air is continuously supplied for a certain period (in a batch) from below through a diffused aeration system to dissolve oxygen into the water. Under continuous aeration, aerobic bacteria oxidize most of the organic compounds in the wastewater.
After the aeration time is complete, aeration stops, allowing the sludge in the wastewater to settle at the bottom of the tank. A portion of this sludge is automatically pumped back to the sludge storage tank, while the water on top of the SBR tank is collected into the disinfection tank.

2.3 Aerotank

SBR is a type of Aerotank. When building an SBR tank, wastewater only needs to pass through a screen, grit chamber, and oil separator (if necessary) before being directly fed into the tank. The advantage is that it can remove nitrogen and phosphorus compounds when operated according to the correct aerobic, anoxic, and anaerobic processes.
The SBR tank operates in 5 phases:

Fill Phase: Water is pumped in over 1-3 hours. Wastewater is introduced into the tank throughout the fill phase. The reaction tank operates in consecutive batches, and depending on the treatment goal and incoming BOD levels, the filling process can be adjusted flexibly: fill-static, fill-mix, fill-aerate.
React Phase (Aeration): A biochemical reaction occurs between the wastewater and activated sludge by aeration or surface agitation to supply oxygen to the water and mix the contents evenly. The aeration time depends on the wastewater quality, typically around 2 hours. During this phase, nitrification can occur, converting nitrogen from N-NH3 to N-NO22- and quickly to N-NO3-.
Settle Phase: Water clarification occurs. This process takes place in a static environment, achieving 100% hydraulic efficiency of the tank. The settling and sludge thickening time usually finishes earlier than 2 hours.
Draw Phase: Approximately 0.5 hours.
Idle Phase: Waiting for the next batch, the idle time depends on the operation of the previous 4 processes and the number of tanks, and the order in which the source water is introduced into the tank.

Sludge disposal is an important stage not included in the basic 5 stages but significantly impacts the system's productivity. The volume and frequency of sludge disposal are determined by the required productivity, similar to a continuous operation system. In batch systems, sludge disposal is usually carried out during the settling or decanting stages. The unique characteristic of the SBR tank is that there is no need to recirculate activated sludge.
Both aeration and settling processes occur in the same tank, so there is no loss of activated sludge during the reaction phase, and no need to recirculate activated sludge from the settling tank to maintain concentration. After treatment, the wastewater meets the Column A standard of QCVN 40:2011/BTNMT and is allowed to be discharged into the environment.

3. Advantages and Disadvantages of SBR Treatment Technology

Advantages: Due to its simple and durable design, SBR tanks save costs, labor, and time for construction and design. They effectively treat wastewater with high pollution concentrations and have a high capacity to remove nitrogen and phosphorus. They are easy to control in case of incidents, stable, and flexible in operation. They can be used for all systems and capacities. Additionally, they are energy-efficient.
Disadvantages: SBR tanks require sophisticated and modern monitoring systems. Maintenance is relatively difficult, and operation requires highly skilled personnel. The tanks are also prone to clogging due to sludge. If the auxiliary tank behind the SBR tank is subject to heavy shock loads, an additional equalization tank may need to be designed to assist.