Present situation of sewage treatment in China

The production of sewage treatment equipment, in China, began in the late 1970s, when the level of standardization and serialization are very low and stereotyping products are less. Since entering 1990s, the relevant state departments have made technological transformation to the main sewage treatment and also improved its manufacturing capacity and level, so the production level of urban sewage treatment equipment and its accompanying general equipments have been greatly improved. In recent years, some new methods and techniques with its advantages and disadvantages have been applied to industrial wastewater treatment. Simple biological oxidation makes the water contains a certain amount of refractory organic matter and the value of COD in water is too high, which can not fully meet the emission standards. Although the adsorption method can remove the COD, but it has the problems about regeneration of the adsorbent and secondary pollution; Catalytic oxidation method can degrade the biodegradable organic matter, but its operating costs are too high in practical applications. With the growing maturing of microwave technology, people note the application potential of microwave in the field of environmental protection such as atmosphere, wastewater, solid waste treatment and environmental monitoring. That is, it has the features of fast and efficient, simple operation, saving time and energy and lower cost.

Principle of Microwave Technology in Wastewater Treatment

Microwave heating of the molecules of different substances in the field, while it also has a strong catalytic effect on physical and chemical reaction to absorbing materials; particles in the field rapidly settled and converged, under the action of the microwave field, and are separated from the water.

As the microwave can directly heat of the absorbing material molecules, when the wastewater placed in the microwave field, their temperature can be quickly increased and effectively kill microorganisms; In addition, due to the penetration of the microwave to fluid, the fluid can be heated evenly; as the materials molecules can directly transform microwave energy into heat energy, the whole process will not bring any new pollutants and it greatly saves energy consumption.

The Main Function of Microwave in Wastewater Treatment

1. The chemical action of microwave energy.

Microwave can polarize water molecules and organic compounds molecules and forms transition state products between organic compounds and sensitizers. This process effectively reduces the oxidation and breaks down activation energy required by hazardous organic compounds and accelerates reaction.

2. The Physical Function of Microwave Energy.

Microwave can heat and polarize water and pollutant molecules, further improve oxidation and resolve harmful organic matters to provide the required activation energy.

3. Heating and catalysis function of microwave energy on water and pollutants molecules.

Microwave makes the precipitation formed by accumulation matters more complete and faster.

A large number of engineering practices have proved that microwave treatment technology has significant removal effect to pollutants in sewage.

The removal rate of impurity including shade, sulfides, suspended solids, CODcr, BOD5, volatile phenol and phosphorus in water is more than 90%, and that of ammonia and anionic detergents are around 75% and 80% respectively.

There are a lot of phosphorus in settling sludge (about 300 times); a small amount of mud, accounting for about 3% of the water.

After treatment, the test items meet the first-class standard requirements written in《sewage discharge standard》(GB8978-1996), in addition, tested by authoritative professional sector, microwave leakage energy is much lower than national standard, that proves it is safe to human body.

Microwave water treatment process

Through the grille (such as urban sewage), gravel, wood, plastic and other large debris are cleared; and then it is entering regulation pool, the water quality and flow are buffered; After regulation pool, the sewage into the mixer, by adding additives, they are together into the microwave reactor; In the reactor, additives and pollutants take place physical and chemical reaction and microwave low-temperature catalytic reaction；Finally, they are separated each other in filtration- integration unit to achieve discharging or reusing purposes.

Under the combined action of additives and microwave, the pollutants in the water undergo intense catalysis and physicochemical reaction, they are converted to insoluble matter or gases separated from the water. Under the action of microwave and additives, macromolecules and refractory organic pollutants are decomposed into small molecules, which are combined with additives to form floccules to be removed. Metal ions are directly composed flocculent precipitate with additive; ammonia is converted to ammonia; Phosphorus in water is converted to insoluble phosphate that is also removed after precipitation.

Advantages of microwave sewage treatment:

1. Not subject to change

Microwave Technology is not affected by climate, water temperature and water quality; meanwhile, According to the medium situation, we can adjust the amount of microwave generation and dosage to achieve the desired results.

2. Low operating costs

When we use microwave technology to do treatment job to sewage, the heavy metals, phosphorous, nitrogen and cyanobacteria are also be handled at the same time; In this process, this technology produces less mud and does not need odor treatment equipment and no secondary pollution. Its operating costs can be saved 20 to 30% compared with traditional process.

3. Less investment, less floor space

Overall volume of microwave sewage treatment system is small and does not need a large number of buildings. This advantage greatly saves the land and reduces pool volume.

4. Sludge and exhaust be done together

When the microwave is treating sewage, both parasite eggs and viruses are killed; there is no those things and smell in emission sludge. That is, it does not produce mosquitoes and mosquitoes and secondary pollution; as the sludge concentration is high, they are easy to be dried, press-filtered, and transported.

5. Engineering miniaturization

We can take a small and decentralized way to block the source of pollution and reduce the huge pipeline network. By means of simplifying the technological process to reduce the project cost and save expenses.

Application Scope of Microwave Wastewater Treatment

1. Hospital sewage.

DO treatment and reuse for sewage from large and medium-sized hospitals, medical schools, as well as remote mountain hospitals and rural hospitals.

2. Domestic sewage.

That includes municipal (living area), large hotels and leisure and tourism resort.

3. Industrial wastewater.

Such as alcohol waste mash, difficult organic wastewater, tannery wastewater, monosodium glutamate plant wastewater, corn brewing wastewater, beer wastewater, papermaking wastewater (including pulp, straw pulp, wood pulp and other waste water), electroplating wastewater, coking plant wastewater, thermal power plant wastewater, municipal production system wastewater, chemical fiber plant wastewater, fluorescent plant wastewater, pharmaceutical wastewater, bleaching and dyeing, dyeing and printing plant wastewater, beneficiation, metallurgical plant wastewater, spices plant wastewater, percolate from landfill and so on.

4. Rivers and lakes sewage.

River treatment, landscape water recycling, the removal of organic matters in rivers and lakes, heavy metals, suspended solids, cyanobacteria, color, smell, kill pathogens in water microorganisms.

Prospects of Microwave Wastewater Treatment

Microwave sewage treatment technology has changed the traditional way of sewage treatment and it makes the treatment methods more simple and effective. It really achieved small-scale decentralization of sewage treatment engineering which is particularly suitable to demand from enterprises and district sewage. 

Because of the output of the sludge is very small with good water quality and as this sewage treatment technology fully meets the emission or recycling requirements and being strong controlled and easy to adjust and be adaptable, microwave sewage treatment technology has been gained highly attention from different national experts and with the emphasis on water resources and the continuous exploration and development of microwave technology, we believe that microwave technology will bring us enormous economic and social benefits.