The upflow anaerobic sludge blanket reactor (UASB) is a single tank process. Wastewater enters the reactor from the bottom, and flows upward. A suspended sludge blanket filters and treats the wastewater as the wastewater flows through it .
What is meant by UASB reactor?
Up flow anaerobic sludge blanket technology also known as UASB reactor is a form of anaerobic digester which used in wastewater treatment. UASB reactor is a methane-producing digester, which uses an anaerobicprocess and forming a blanket of granular sludge and is processed by the anaerobic microorganisms.
What is meant by UASB reactor state an advantage of it?
A distinctive advantage of the UASB reactor is the very high loading rate achieved by the systems (Speece, 1996). UASB reactors can be used for high-strength wastewaters with a volatile suspended solids (VSS):COD ratio of less than one and with COD concentrations between 500 and 20000 mg/L (Mulligan, 2002).
What is sludge digestion process?
Sludge digestion is a biological process in which organic solids are decomposed into stable substances . Digestion reduces the total mass of solids, destroys pathogens, and makes it easier to dewater or dry the sludge. Digested sludge is inoffensive, having the appearance and characteristics of a rich potting soil.
Is the rate limiting step in UASB reactors?
Hydrolysis is commonly the limiting step at low temperature setting. Therefore, the UASB reactors for domestic wastewater treatment having high level of suspended solids are practicable only at higher temperature which may require an outside heat source [32, 40].
Who invented UASB?
Upflow anaerobic sludge blanket (UASB) reactors. One of the most remarkable and significant developments in high-rate anaerobic treatment technology is the invention of UASB reactor by Lettinga et al. (1976, 1980) in Netherlands.
What is required to keep the activated sludge suspended?
3. What is required to keep the activated sludge suspended? Explanation: To maintain the aerobic conditions and to keep the activated sludge suspended, a continuous and well-timed supply of oxygen is required . Flocs of bacteria, which are suspended and mixed with wastewater is used for the process.
Is treated in activated sludge reactor?
Explanation: Pre-treated sludge is treated in an activated sludge reactor. ... Explanation: Clarifier (settling tank) is the next reactor where the solids (mostly cells, called sludge at this stage) are separated from the water. The system is commonly operated in continuous mode (as opposed to batch mode).
Why is the sludge aerated?
Aeration in an activated sludge process is based on pumping air into a tank , which promotes the microbial growth in the wastewater. ... After settling in a separate settling tank, bacteria forming the “activated sludge” flocks are continually recirculated back to the aeration basin to increase the rate of decomposition.
Why is sludge dewatering necessary?
Why is Dewatering Necessary? The two main purposes of sludge dewatering is for waste minimization and to achieve overall cost efficiency for disposal . Additionally, stabilized sludge can be handled more safely and can reduce health hazards. Some sludges actually have a great beneficial reuse and can be land applied.
What methods are used to treat sludge?
Many sludges are treated using a variety of digestion techniques, the purpose of which is to reduce the amount of organic matter and the number of disease-causing microorganisms present in the solids. The most common treatment options include anaerobic digestion, aerobic digestion, and composting .
What are two basic types of sludge digestion unit?
Two different types in anaerobic sludge digestion process are in practice: (1) Low rate digestion: a large storage tank , occasionally, with some heating facility, and (2) High rate digestion: with pre-thickening of raw sludge, complete mixing, heating and uniform feeding of raw sludge (CPHEEO 2012).
Which is used to remove sludge?
Dewatering decreases sludge liquid volume as much as 90 percent. Digested sludge is put through large centrifuges that work in the same fashion as a washing machine spin cycle. The spinning centrifuge produces a force that separates the majority of the water from the sludge solid, creating a biosolid substance.
Which type of bacteria are used in trickling filters?
Which type of bacteria are used in trickling filters? Explanation: Facultative bacteria are used in trickling filters. Pseudomonas and Alcaligenes are some of the strains used in these filters. Also, Flavobacterium and Achromobacter are also used in this type of treatment.
What is meant by oxidation pond?
Oxidation ponds, also called lagoons or stabilization ponds, are large, shallow ponds designed to treat wastewater through the interaction of sunlight, bacteria, and algae . ... During the process of photosynthesis, the algae release oxygen needed by aerobic bacteria.
What is the performance of primary sedimentation tank?
Primary sedimentation tanks can be rectangular or circular, and typically operate with a hydraulic detention time of 1.5-3 hours based on the average daily flowrate (Figures 9 and 10).
