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Reclaimed Water Recycling and Reclaimed Water Treatment Engineering
Created on 02.28
Reclaimed Water Treatment
The company provides full-process services from wastewater sampling, water quality testing, process design, pilot testing, intermediate testing, construction drawing design, equipment customization and supply, to construction and subsequent operation.
Reclaimed water refers to recycled water. In fact, reclaimed water treatment is not far from our lives. Many families are accustomed to collecting water from washing clothes and vegetables to flush toilets and mop floors. In fact, this is the most primitive and simplest method of reclaimed water treatment.
Reclaimed water is water with better qualitydomestic sewageAfter simple technical treatment, it is used as non-potable water. Reclaimed water is mainly used for car washing, landscape spraying, toilet flushing, cooling water, etc., which fully utilizes water resources and reducessewagepollution to the environment caused by direct discharge. Forfreshwater resourcescities lacking water and with severe water supply shortages,reclaimed water systemis an important way to alleviate water scarcity, prevent water pollution, and protect the environment.
Reclaimed Water Treatment: MBR Membrane Process
A new water treatment technology combined with membrane separation technology. There are many types of membranes. Classified by separation mechanism, there are reactive membranes, ion exchange membranes, osmotic membranes, etc.; classified by membrane properties, there are natural membranes (biofilms) and synthetic membranes (organic membranes and inorganic membranes); classified by membrane structure, there are flat sheet, tubular, spiral, and hollow fiber types.
The membrane-bioreactor is mainly composed of membrane separation components and a bioreactor. The commonly referred to membrane-bioreactor is actually a general term for three types of reactors: ① Aeration Membrane Bioreactor (AMBR); ② Extractive Membrane Bioreactor (EMBR); ③ Solid/Liquid Separation Membrane Bioreactor (SLSMBR, abbreviated as MBR).
Characteristics of MBR process
Compared with many traditional biological water treatment processes, MBR has the following main characteristics:
I. High-quality and stable effluent quality
Due to the high separation efficiency of the membrane, the separation effect is far better than that of traditional sedimentation tanks. The treated effluent is extremely clear, with suspended solids and turbidity close to zero. Bacteria and viruses are significantly removed. The effluent quality is superior to the water quality standard for non-potable municipal reclaimed water issued by the Ministry of Construction (CJ25.1-89), and it can be directly reused as non-potable municipal reclaimed water.
At the same time, membrane separation also completely retains microorganisms within the bioreactor, allowing for a high concentration of microorganisms to be maintained within the system. This not only improves the overall removal efficiency of pollutants by the reaction device and ensures good effluent water quality, but also makes the reactor highly adaptable to various changes in influent load (water quality and quantity), resistant to shock loads, and capable of consistently producing high-quality effluent water.
II. Low excess sludge production
This process can operate under high volumetric load and low sludge load, resulting in low excess sludge production (theoretically achieving zero sludge discharge), thereby reducing sludge treatment costs.
III. Small footprint, not limited by installation location
A high concentration of microorganisms can be maintained within the bioreactor, leading to a high volumetric load for the treatment device and significantly saving on footprint. The process flow is simple, the structure is compact, and the footprint is small, making it unrestricted by installation location and suitable for any scenario. It can be designed as above-ground, semi-underground, or underground.
IV. Removal of ammonia nitrogen and refractory organic matter
Because microorganisms are completely retained within the bioreactor, it is conducive to the retention and growth of slow-growing microorganisms such as nitrifying bacteria, thereby improving the system's nitrification efficiency. At the same time, it can increase the hydraulic retention time of some refractory organic matter in the system, which is beneficial for improving the degradation efficiency of refractory organic matter.
V. Convenient operation and management, easy to achieve automatic control
This process achieves complete separation of Hydraulic Retention Time (HRT) and Sludge Retention Time (SRT), making operation control more flexible and stable. It is a new technology in wastewater treatment that is easy to equip and can achieve microcomputer automatic control, thus making operation and management more convenient.
VI. Easy to upgrade from traditional processes
This process can be used as a tertiary treatment unit for traditional wastewater treatment processes, with broad application prospects in areas such as advanced treatment of effluent from urban secondary wastewater treatment plants (thereby achieving large-scale reuse of urban wastewater).
Membrane-Bioreactors also have some shortcomings. These are mainly reflected in the following aspects:
o The high cost of membranes makes the capital investment for membrane bioreactors higher than traditional wastewater treatment processes.
o Membrane fouling occurs easily, causing inconvenience in operation and management.
o High energy consumption: Firstly, the MBR sludge-water separation process requires maintaining a certain membrane driving pressure. Secondly, the MLSS concentration in the MBR tank is very high, requiring increased aeration intensity to maintain sufficient oxygen transfer rate. Additionally, to increase membrane flux and reduce membrane fouling, the flow rate must be increased to scour the membrane surface, resulting in higher energy consumption for MBR compared to traditional biological treatment processes.
Integrated equipment for reclaimed water treatment
Integrated reclaimed water treatment equipmentThe use of membrane bioreactor technology is a combination of biological treatment technology andMembrane Separationa new process combined with technology, replacing the traditional processsecondary sedimentation tank, it can efficiently perform solid-liquid separation, obtaining stable reclaimed water for direct use. It can also maintain a high concentration of microbial mass in the biological tank, with lessexcess sludge, effectively removingammonia nitrogen, and the effluentsuspended solidsandturbidityis close to zero, bacteria and viruses in the effluent are significantly removed, energy consumption is low, and the footprint is small.
Reclaimed Water Treatment: AAO Process
AAO process is the abbreviation of anaerobic-anoxic-oxic combined process, which consists of three stages of biological treatment units. Its difference from the single-stage AO process is the addition of an anaerobic reactor in the front stage, which aims to degrade and remove some refractory organic matter in the wastewater through the anaerobic process, thereby improving the biodegradability of the wastewater and providing a carbon source suitable for denitrification in the subsequent anoxic stage, ultimately achieving efficient removal of COD, BOD, N, and P. The process flow of the AAO system is: wastewater enters the anaerobic reactor after pretreatment, where high COD substances are partially decomposed, then enters the anoxic stage for denitrification, followed by the aerobic stage for oxidative degradation of organic matter and nitrification. To ensure the efficiency of denitrification, a portion of the effluent from the aerobic stage is returned to the anoxic stage and mixed with the effluent from the anaerobic stage to fully utilize the carbon source in the wastewater. The other portion of the effluent enters the secondary clarifier, where activated sludge is separated and discharged as effluent. The sludge is directly returned to the anaerobic stage.
Contact Oxidation Process for Reclaimed Water Treatment
Contact oxidation method is a new biochemical wastewater treatment method that combines the characteristics of activated sludge method and biofilm method. The main equipment for this method is the biological contact oxidation filter. In an airtight aeration tank, fillers such as coke, gravel, and plastic honeycomb are installed. The fillers are submerged in water, and a blower is used to aerate and oxygenate from the bottom of the fillers, which is called forced aeration. Air passes freely from bottom to top, carrying the wastewater to be treated, through the filter material part to the ground. After the air escapes, the wastewater returns from top to bottom between the filter materials to the bottom of the tank. Activated sludge is attached to the surface of the filler and does not flow with the water. Because the biofilm is strongly agitated by the upward airflow and is constantly renewed, the purification effect is improved. The biological contact oxidation method has the advantages of short treatment time, small volume, good purification effect, good and stable effluent quality, no sludge return or expansion, and low power consumption.
Advantages
(1) High volumetric load, strong resistance to shock loads, short treatment time, saving footprint;
(2) High biological activity, with a high concentration of microorganisms;
(3) Low sludge production, no sludge return required;
(4) Good and stable effluent water quality;
(5) Low power consumption, saving energy and operating costs;
(6) Easy biofilm attachment, can operate intermittently;
(7) No sludge bulking problem.
Disadvantages
(1) The biomass on the packing varies depending on the BOD load;
(2) The biofilm can only shed on its own, making it difficult to discharge excess sludge. If it remains between the filter media, it can easily lead to water quality deterioration and affect treatment efficiency.
treatment efficiency;
(3) When honeycomb packing is used, if the load is too high, the biofilm will be thicker and easily block the packing.
(4) Large production of metazoans (e.g., rotifers);
(5) Combined contact packing sometimes affects aeration and agitation.
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