Sewage Treatment


1. Background environment of domestic sewage

According to market research data from Henan Xinhuan Water Treatment Material Co., Ltd., a relatively high proportion of industrial and urban sewage discharge in various countries is still untreated, and some sewage is even directly discharged into rivers, causing serious pollution to water resources. Therefore, properly handling domestic sewage, improving water quality, and protecting water resources have become the consensus of the whole society.


2. YuXinHuan's source analysis of domestic wastewater

Household sewage: containing organic matter, suspended solids, oils, and pathogenic microorganisms, originating from daily washing, bathing, etc.

Public building sewage: contains more pathogens and harmful substances, such as drug residues in hospital sewage, which poses a greater threat.

Commercial wastewater: high content of oil and food residues, and may contain chemical substances such as detergents and disinfectants, making it difficult to treat.

Mixing of urban public facilities and industrial wastewater: containing suspended solids such as sediment, leaves, and possible detergent residues, some mixed with heavy metals and toxic chemicals, posing a serious threat to the environment and requiring strengthened supervision and treatment.


3. Experimental analysis of domestic wastewater composition by YuXinHuan

The composition of domestic sewage is complex, including organic matter, suspended solids, pathogenic microorganisms, plant nutrients, inorganic pollutants, and oils. Organic matter and suspended solids consume dissolved oxygen, deteriorating water quality; Pathogenic microorganisms pose a threat to human health; Excessive nutrients such as nitrogen and phosphorus lead to eutrophication of water bodies; The excessive discharge of inorganic pollutants such as heavy metals also poses a hazard. Oil forms a floating emulsion, which affects the transparency and aesthetics of water bodies.


4. Domestic sewage treatment process

Pre treatment stage: 

Remove suspended solids, floating debris and other impurities in the sewage through equipment such as grids and screens to prevent blockage and wear of subsequent treatment equipment.

Biological treatment stage: 

Utilizing the metabolic process of microorganisms to degrade organic matter in wastewater into harmless substances. At this stage, biological treatment methods such as activated sludge process and biofilm process are usually used.

Deep processing stage: 

On the basis of biological treatment, further remove nutrients such as nitrogen and phosphorus, as well as recalcitrant organic matter from wastewater. This stage usually adopts methods such as coagulation precipitation, filtration, adsorption, ion exchange, etc.


In the deep processing stage, we use YuXinHuan's products--Polyaluminium chloride (PAC)  and Polyacrylamides (PAM), and the following is the description and effect of the use:


Coagulation and precipitation:

Methods: Adding chemicals to the water, Polyaluminium chloride (PAC) can be added at this stage, which hydrolyzes and interacts with the pollutants to form large-particle flocs through the process of coagulation, and then solid-liquid separation is achieved through sedimentation or air flotation.

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Principle of use: Polyaluminium chloride as a coagulant aid, mainly through the compression of the double electric layer, adsorption bridging and precipitation net trapping and other mechanisms, so that the suspended solids, colloids and other impurities in the water to form larger flocs, to facilitate the subsequent separation of the treatment, the suspended solids in the water has a very good effect on the removal of the water, but also to remove some of the color of the water, adaptable, and in a wide range of pH can be maintained in a higher coagulation efficacy.

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Filtration, adsorption

Methods: After coagulation and sedimentation, filtration is usually required to further remove suspended solids and small particles of impurities in the water. In addition, you can add Polyacrylamides (PAM), which is an organic Polymer flocculant, through the adsorption of long-chain molecules, bridging effect, the coagulation of the formation of smaller flocs will be further aggregated into long, dense flocs, to improve the efficiency of precipitation. After filtration, materials such as activated carbon can also be used for adsorption treatment to remove residual pollutants in the water.


Principle of use: the addition of Polyacrylamides can strengthen the coagulation effect, the formation of flocs with a compact structure, which helps to improve the filtration and dewatering efficiency, and is very effective in improving the clarification of the effluent water. At the same time, activated carbon and other adsorption materials can remove organic matter, heavy metal ions and other pollutants in the water to further improve water quality.


Ion exchange

Method: Ion exchange resin and other materials are utilized to remove ionic pollutants in the water, such as heavy metal ions and hardness ions.



Disinfection stage: 

UV disinfection, chlorine disinfection and other methods are used to kill pathogenic microorganisms in the water, ensuring that the effluent quality meets relevant standards.


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5. Case study of domestic sewage treatment

Background:

The urban sewage treatment plant in Shayang County, Jingmen City, Hubei Province adopts the standard domestic sewage AAO process flow, but there are problems in the high-efficiency flocculation tank polyaluminum amide flocculation inclined tube sedimentation process. The site is equipped with automatic aluminum dosing machines, amide automatic dosing machines, aluminum mixing tanks, amide mixing tanks, and inclined tube sedimentation tanks.

Field fault description:

On site feedback shows that the amount of anionic polyacrylamide (PAM) used is relatively large, and there is no sedimentation phenomenon in the inclined tube sedimentation tank, resulting in excessive total phosphorus in the effluent. After small-scale adjustments, it was found that increasing the proportion of anionic PAM can accelerate the precipitation rate, and the total phosphorus after precipitation is qualified. However, this further increases the amount of anionic PAM used.

Solution:

We have had in-depth communication with the client regarding the above-mentioned issues. Explained the reasons why the dosage of anionic PAM cannot be reduced under the current situation, and asked the customer if they are willing to consider increasing the molecular weight of anionic PAM. The customer stated that it depends on the later operational situation and pays attention to whether increasing molecular weight will lead to an increase in supply costs.

After sales results:

Although we have proposed a solution, the problem of high usage of anionic PAM in terminal water plants has not been fundamentally solved. This mainly depends on whether the customer is willing to bear the additional supply costs caused by the increase in molecular weight. We will continue to communicate with our clients, monitor their operations, and provide necessary technical support and advice.

Summary:

When dealing with problems in sewage treatment processes, it is necessary to comprehensively consider multiple factors such as water quality, process, equipment, and cost. When proposing a solution, it is important to communicate fully with the customer, understand their needs and concerns, and work together to find the optimal solution.

This case reminds us that when dealing with problems in sewage treatment processes, it is necessary to comprehensively consider multiple factors such as water quality, process, equipment, and cost. When proposing a solution, it is important to communicate fully with the customer, understand their needs and concerns, and work together to find the optimal solution.


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