Wastewater Treatment Solutions & Technologies

1. Background

Reverse osmosis technology has made great progress in the development field in recent decades. It has great value in the treatment of industrial sewage and domestic sewage and plays an important role. The application of reverse osmosis water treatment equipment needs to select different permeable membranes according to the treatment requirements of pollutants in the water body to ensure the sewage treatment effect.

NEWater will show the application of reverse osmosis equipment in sewage treatment from two aspects, which can realize the process of separating pollutants from sewage, purifying sewage, and improving effluent quality. It is hoped that it can provide solutions for improving the quality of sewage treatment and deepening the application of RO technology.

Figure4 Municipal sewage pool.

2. Industrial Sewage

With the rapid development of the world’s industrial field, the problem of water pollution caused by the disorderly discharge of industrial wastewater also follows. The types of pollutants contained in industrial wastewater from different production directions, raw materials, and production processes are different. Some industrial wastewater contains a large number of heavy metals, a large number of inorganic salts, and a large amount of organic matter. If this industrial wastewater cannot meet the discharge standard, it will cause very serious water pollution problems.

In the process of industrial wastewater treatment, the treated objects mainly include COD chemical oxygen demand, BOD5 biological oxygen demand, SS-suspended solids, heavy metal ions, inorganic salts, etc. In the process of industrial wastewater treatment, the treatment technology and equipment shall be selected according to the characteristics of the treated objects, so as to ensure the quality of treated water and produce part of circulating water for industrial production. It also improves the environmental friendliness of industrial production.

Figure2 Industrial wastewater discharge index.

Reverse osmosis water treatment equipment, as a technology that uses physical characteristics to realize the separation of water and pollutants, has a wide application range and simple operation. On the premise of doing a good job in pretreatment and improving the protection of membrane modules, it can meet the wastewater treatment needs of many industrial enterprises, and it has a broad application space in the field of industrial wastewater treatment.

2.1 Heavy Metal Industrial Wastewater Treatment.

The field of heavy metal industrial wastewater treatment is an early field of reverse osmosis technology and treatment equipment. One of the important purposes of reverse osmosis technology and equipment is to recover heavy metals. As early as the 1970s, reverse osmosis technology has been applied to the treatment of electroplating wastewater. Later, with the continuous maturity of reverse osmosis technology and the gradual improvement of treatment equipment, reverse osmosis began to become one of the main treatment technologies for wastewater containing single or multiple heavy metals. The reverse osmosis water treatment equipment for electroplating wastewater reuse launched by NEWater.

Figure3 NEWater electroplating wastewater reuse reverse osmosis water treatment equipment.

The interception rate of the membrane module of the electroplating wastewater reuse reverse osmosis water treatment equipment for heavy metal ions can reach more than 90%, and the interception rate of some heavy metals can reach more than 99%. Therefore, reverse osmosis water treatment equipment is the core equipment of heavy metal industrial wastewater treatment. In the treatment of heavy metal industrial wastewater, it is necessary to adjust the pH value of heavy metal wastewater to neutral, and then recover heavy metal ions with the help of reverse osmosis and ultrafiltration technology.

The process flow of reverse osmosis reuse equipment for electroplating wastewater is as follows: Electroplating Wastewater → Raw Water Tank (Self Provided) → Raw Water Pump → Flocculation Dosing Device → Mechanical Filter → Activated Carbon Filter → Ultrafiltration Device → Ultrafiltration Tank Self Provided → Scale Inhibition Dosing Device → Security FilterHigh-Pressure Pump → Reverse Osmosis Host (Cleaning Device) → Pure Water Tank (Self Provided) → Water Point.

Figure4 Process flow of reverse osmosis reuse equipment for electroplating wastewater.

2.2 Wastewater Treatment Of Printing And Dyeing Industry.

Printing and dyeing textile wastewater is a special kind of industrial wastewater. The pollutant composition is very complex. The wastewater comes from multiple process links of printing and dyeing textile enterprises. Therefore, it contains a variety of pollutants such as dyes, oil agents, additives, sizing materials, fiber impurities, and so on. Printing and dyeing industrial wastewater contains many toxic substances, such as heavy metal elements, nitro compounds, amines, etc. If these substances are discharged without treatment, they will directly affect the safety of the water environment.

The reverse osmosis membrane wastewater treatment equipment developed by NEWater for reuse treatment of the printing and dyeing industry is important technical equipment for the treatment of printing and dyeing industrial wastewater. It can effectively remove inorganic salts and toxic substances, reduce the chemical oxygen demand, biological oxygen demand, chromaticity, and other parameters of printing and dyeing wastewater, and make the printing and dyeing wastewater meet the discharge standard. In the treatment of printing and dyeing textile wastewater, the application of reverse osmosis water treatment equipment can achieve a 93% removal rate of inorganic salts.

Figure6 Advanced treatment of printing and dyeing wastewater by ultrafiltration and reverse osmosis double-membrane technology.

The advanced treatment process of printing and dyeing wastewater by ultrafiltration reverse osmosis double-membrane technology is as follows: Printing And Dyeing Wastewater → Grid → Regulating Tank → Primary Sedimentation Tank → Anaerobic Tank → Aerobic Tank → Secondary Sedimentation Tank → Water Storage Tank → Booster Pump (Pressure Gauge) → Ultrafiltration Module (Valve Connected To Anaerobic Tank) → Water Storage Tank (Constant Temperature Controller) → High-Pressure Pump → Pressure Buffer Tank (Pressure Gauge) → Reverse Osmosis Component → Filtrate Collection.

2.3 Organic Chemical Wastewater Treatment.

In the field of chemical production, chemical wastewater often contains a large amount of organic matter. If this organic matter is discharged directly without standard treatment, it will inevitably lead to water pollution. Through RO water treatment equipment, the effective interception of polymer organics can be realized, the chemical wastewater can be reused as a clean water body, and the emission reduction of sewage can be realized.

Chemical wastewater with petroleum as raw materials often contains organic substances such as oil, sulfur, benzene, phenol, cyanogen, and naphthenic acid, which makes it difficult to degrade petrochemical wastewater and realize standard discharge through traditional biological treatment technology.

Figure7 NEWater organic chemical wastewater reverses osmosis treatment equipment.

The reverse osmosis water treatment equipment developed by NEWater can effectively intercept and concentrate the organic matter in chemical wastewater and improve the effluent quality. It can not only reduce the sewage discharge of chemical enterprises but also reuse the available substances and clean water bodies.

Production enterprises attach great importance to production cost, which is related to the profit space and core competitiveness of enterprises. The investment in wastewater treatment is a part of the production cost. The application of reverse osmosis in wastewater treatment of industrial enterprises can achieve the effects of low cost, low energy consumption, high quality, and high efficiency.

3. Domestic Sewage.

3.1 Ultrafiltration Combined Reverse Osmosis Technology.

With the rapid development of the economy, the increase in population, the acceleration of urban industrialization, the improvement of people’s living standards, serious industrial pollution, and the shortage of water resources, water consumption increases year by year. Especially in arid and semi-arid areas, wastewater reuse has become one of the research focuses of international experts and scholars. Domestic sewage is an important potential water resource. At present, the world is vigorously advocating “Wastewater Recycling”. Membrane technology is the key technology of wastewater reuse.

Because the effluent from traditional sewage treatment contains suspended solids, organic matter, microorganisms and inorganic matter, the combined process of ultrafiltration and reverse osmosis is an ideal technology to solve the problem of sewage reuse. It is mainly used for the reuse of reclaimed water after domestic sewage treatment, the purification of tap water, groundwater, and surface water, and the pre-treatment of large-scale reverse osmosis systems.

Figure8 Ultrafiltration equipment of reverse osmosis process for domestic sewage reuse in NEWater.

The purpose of the “Ultrafiltration and Reverse Osmosis” device developed by NEWater is to treat urban secondary domestic sewage by ultrafiltration and reverse osmosis and realize the treatment effect of ultrafiltration and reverse osmosis on COD, T-N, NH3-N, T-P, and Cl-.

Figure9 "Ultrafiltration and reverse osmosis" process flow.

The ultrafiltration treatment of the “Ultrafiltration and Reverse Osmosis” process is used as the pretreatment system of the reverse osmosis system. Ultrafiltration is used as the pretreatment of reverse osmosis; Reverse osmosis device: Raw Water Tank → Multi-Media Filter → Activated Carbon Filter → Ion Softening System → Dosing System → Precision Filter; Scale inhibitor dosing device: To prevent chemical scaling at the concentrated water side of reverse osmosis, especially at the concentrated water side of reverse osmosis pressure vessel, to affect the performance of membrane elements.

Scale inhibitor, reducing agent, and dosing device shall be added before reverse osmosis water inflow. The residual chlorine in the influent of reverse osmosis equipment shall be less than 0.1mg/L, and a sodium sulfite reducing agent may be added to eliminate the effective components of oxidizing bactericide and prevent its damage to reverse osmosis membrane elements.

3.2 Pollution-Resistant Reverse Osmosis Membrane Technology.

NEWater has newly developed a pollution-resistant reverse osmosis membrane.  The desalination rate is similar to that of an ordinary reverse osmosis membrane, but its water production flux is larger. And the surface is smoother than that of ordinary reverse osmosis. This is mainly because the functional monomer and manufacturing process used in the preparation of NEWater’s pollution-resistant membrane is different from that of ordinary reverse osmosis membrane. Therefore, the membrane has relatively small adsorption of ordinary pollutants and it is easy to clean the polluted membrane so that the membrane has better pollution resistance.

Figure10 NEWater pollution resistant reverse osmosis membrane domestic sewage treatment equipment.

The process flow is: Domestic Sewage → Sewage Treatment Plant → Secondary Drainage → Water Pump → Reverse Osmosis System → Raw Water Tank → Metering Pump (Bactericide) → Alkali → Booster Pump → Quartz Sand Filter → Pretreatment System (Multi-Media Filter With Granular Activated Carbon In The Upper Layer, Manganese Sand In The Middle And Fine Sand In The Lower Layer) → Appropriate Amount Of Reducing Agent And Scale Inhibitor → Intermediate Water Tank → High-Pressure Pump → Pollution Resistant Membrane Unit → Produced Water. And concentrated water returns to the treatment tank of the sewage treatment plant.

Figure11 Process flow chart of micro polluted water treatment by pollution resistant reverse osmosis membrane.

Reverse osmosis water treatment equipment can effectively reduce the total wastewater discharge of industrial enterprises and make the effluent meet the industrial production discharge standard; At the same time, it can realize the reuse of domestic sewage, save water resources, and effectively improve water safety of urban and rural residents.

Whether you have any questions or needs in industrial sewage treatment or domestic sewage treatment, contact NEWater via info@newater.com and we will provide sustainable and inclusive solutions implemented worldwide. Work together with modern industry and urban life to create new water and develop broader technological prospects!

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