Treatment process of printing wastewater with the

2022-08-15
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Green printing: ink printing wastewater treatment process

release date: Source: Bisheng editor: Chinese packaging browsing times: 647 copyright and disclaimer

core tip: in the production and application of water-based ink, the moving speed of 9 beam (shortcut keys and free settings) is 0.2 ~ 500mm/min, and a certain amount of wastewater will be generated due to the cleaning of the equipment. The ever-changing color of water-based ink causes the chemical composition of its wastewater to be quite complex, which has the characteristics of high COD, high chroma and difficult biodegradation. Once it enters the water body, it will cause serious pollution to the water environment. The continuous R & D and improvement of wastewater treatment workers provide strong support for Guangya aluminum's entry into the fields of industrial materials, aerospace, high-speed rail, shipping and so on. Technology is closely related to the types and characteristics of water-based inks

[China Packaging News] during the production and application of water-based ink, a certain amount of wastewater will be generated due to the cleaning of equipment. The ever-changing color of water-based ink causes the chemical composition of its wastewater to be quite complex, which has the characteristics of high COD, high chroma and difficult biodegradation. Once it enters the water body, it will cause serious pollution to the water environment. The treatment process of wastewater is closely related to the types and characteristics of water-based inks. At present, the research and application of water-based ink wastewater treatment mainly focus on chemical coagulation, electrolysis, coagulation air flotation, coagulation air flotation micro electrolysis, chemical oxidation coagulation and other pretreatment methods combined with biochemical processes

1 electrolysis method

in some pretreatment methods, electrolysis method shows better performance, and domestic research and application have a certain foundation; The advantages of electrolytic method lie in: (1) what is produced in the process? Oh selectively reacts directly with organic pollutants in wastewater to degrade it into carbon dioxide, water and simple organics, with no or little secondary pollution; (2) The electrolysis process is accompanied by the function of air flotation; (3) The energy efficiency is high, and the electrochemical process can generally be carried out under normal temperature and pressure; (4) It can be treated alone or combined with other treatments. For example, as a pretreatment, the biodegradability of wastewater can be improved, and the biodegradability of wastewater after pretreatment can be greatly improved; (5) Electrolysis equipment and its operation are generally simple. The application of the environmental engineering design center of Maoming Environmental Protection Bureau in the sewage treatment system of Maoming Sakata Ink Co., Ltd. has proved that the treated sewage can be discharged up to the standard by electrolytic pretreatment and biochemical treatment

decontamination mechanism of electrolytic method

as a treatment method with strong adaptability, high efficiency, short time and no secondary pollution for various sewage treatment, electrolytic method uses iron plate as anode and aluminum plate as cathode to electrochemically treat sewage under the action of strong current, Its main chemical reaction formula is:

anode: fe---fe2++2e

cathode: 2h to protect children's health ++2e---h2

as the anode, the iron plate slowly dissolves in the electrolysis process, enters the wastewater in the form of, and hydrolyzes to form Fe (OH) 2. These Fe (OH) 2 have high condensation, and produce new ecological hydrogen at the cathode. Its reduction ability is very strong, and it plays a reduction reaction with pollutants in the wastewater, At the same time, macromolecular pollutants are decomposed into small molecules. The electrolysis process includes oxidation, reduction, condensation and air flotation

1) oxidation. Oxidation in the electrolysis process can be divided into direct oxidation (that is, oxidation occurs when pollutants lose electrons directly at the anode) and indirect oxidation. Indirect oxidation refers to the use of anions with low electrode potential in solution (such as oh-, cl-). The active substances [o], Cl2, etc., which lose electrons in the anode and generate new strong oxidants, make the pollutants lose electrons and play the role of oxidative decomposition, so as to reduce BOD5, COD, NH3-N, etc. in the stock solution

2) reduction. Reduction in electrolysis can also be divided into two categories. One is direct reduction, that is, the pollutants get electrons directly on the cathode and reduce; The other is indirect reduction. The cation in the pollutant first obtains electrons at the cathode, so that the electrons obtained at the cathode by the cation of high or low valence metal in the electrolyte are directly reduced to low valence cations or metal precipitation

3) coagulation. Soluble anodes, such as iron, aluminum and other anodes, are powered by DC. After the anode loses electrons, metal cations fe2+, al3+ are formed, and metal hydroxide colloidal flocculants are formed with oh- in the solution. Its adsorption capacity is very strong, and pollutants can be adsorbed to form flocs

4) air flotation. In the process of electrolysis of wastewater, when the voltage reaches the decomposition voltage of water, hydrogen and oxygen are separated out on the cathode and anode respectively, and the oh- produced by the electrolysis process on the other side reacts with organic matter to produce carbon dioxide in 2012. These gases have small bubble size and high dispersion, and can be used as a carrier to adhere to the suspended solids in the water and float up, so it is easy to remove pollutants. Electro flotation can remove both hydrophobic and hydrophilic pollutants from wastewater

2 UASB Process

up flow anaerobic sludge bed (UASB) process is a technology that can convert pollutants in sewage into renewable clean energy biogas due to its dual characteristics of anaerobic filtration and anaerobic activated sludge process. In 1971, Professor lettinga of Wageningen Agricultural University in the Netherlands invented a three-phase separator through physical structure design and using the difference of the effect of gravity field on substances with different densities. By separating the residence time of activated sludge from that of wastewater, the prototype of upflow anaerobic sludge bed (UASB) reactor was formed. In 1974, when CSM company of the Netherlands treated sugar beet wastewater in its 6m3 reactor, it found the biopolymer structure formed by the self immobilization mechanism of activated sludge, namely granular sludge. The emergence of granular sludge not only promoted the application and development of the second generation anaerobic reactor represented by UASB, but also laid the foundation for the birth of the third generation anaerobic reactor

uasb process has strong adaptability to sewage with different solid content, and its structure, operation, maintenance and management are relatively simple, and the cost is relatively low. The technology has been mature, and is increasingly valued by the sewage treatment industry, and is widely welcomed and applied

3 air flotation

the dispersed micro air robe is used as a carrier to adhere to the suspended pollutants in the wastewater, making its buoyancy greater than gravity and resistance, so that the pollutants float to the water surface to form foam, and then use the slag scraper to scrape the foam from the water surface, and the process of realizing solid-liquid or liquid-liquid separation is called air flotation

the principle of oil removal by air flotation is mainly to use the characteristics that the surface tension between oil and water is greater than that between oil and gas, and the oil is hydrophobic while the gas is relatively hydrophilic. At the same time, a flotation agent is added to make the oil particles adhere to the bubbles, and the bubbles adsorb the oil and suspended solids to float to the water surface, so as to achieve the purpose of separation. The air flotation method mainly removes the residual floating oil and dispersed oil without surfactant. The disadvantage is that there are many rotating parts of the equipment, the oily sewage has high salt content and strong corrosivity, so the stability of the process operation is poor

4 coagulation method

coagulation method is to add a certain amount of agent to the sewage, and make the pollutants in the water condense and settle after destabilization, bridging and other reaction processes. Pollutants in colloidal state in water usually have negative charges, and colloidal particles repel each other to form a stable mixture. If the dielectric with opposite charges in water (i.e. coagulant) can change the colloidal particles in sewage to be electrically neutral, and condense into large particles under the action of molecular gravity to sink

this method is used to treat oily wastewater, dyeing wastewater, wool washing wastewater, etc. this method can be used independently or in combination with other methods, generally as pretreatment, intermediate treatment and advanced treatment. Commonly used coagulants include aluminum sulfate, basic aluminum chloride, ferrous sulfate, ferric chloride, etc

5 biological contact oxidation method

biological contact oxidation method is one of the main facilities of biofilm method. Biofilm method is a general term for a large class of biological treatment methods, which mainly uses microorganisms (i.e. biofilm) attached to the surface of some solids for organic sewage treatment. Biofilm is an ecosystem composed of highly dense aerobic bacteria, anaerobic bacteria, facultative bacteria, fungi, protozoa and algae. The solid medium attached to biofilm is called filter material or carrier. Biofilm can be divided into Qingqi layer, Haoqi layer, attached water layer and moving water layer from the filter material outward. The principle is that the biofilm first adsorbs the organic matter in the attached water layer, which is decomposed by the aerobic bacteria in the aerobic layer, and then enters the anaerobic layer for anaerobic decomposition. The flowing water layer washes away the aged biofilm to grow a new biofilm, so as to achieve the purpose of purifying sewage. The aging biofilm continues to fall off and is removed by sedimentation with the water flowing into the secondary sedimentation

the treatment structure of biological contact oxidation method is submerged aerated biofilter, also known as biological contact oxidation tank

the biological contact oxidation tank is equipped with fillers, which are submerged in the waste water, and the fillers are covered with biofilm. During the contact between the waste water and the biofilm, the organic matter in the water is adsorbed, oxidized, decomposed and transformed into a new biofilm by microorganisms. The biofilm falling off the filler is removed after flowing into the secondary sedimentation tank, and the wastewater is purified. In the contact oxidation tank, the oxygen needed by microorganisms comes from water, and the waste water constantly replenishes the lost dissolved oxygen from the bubbling air. The air enters the water flow through the perforated air distribution pipe at the bottom of the pool. When the bubble rises, it supplies oxygen to the wastewater and sometimes returns the pool water

characteristics of biological contact oxidation method:

(1) due to the large specific surface area of the filler, the oxygenation condition in the pool is good. The biological solids per unit volume in the biological contact oxidation tank is higher than that in the activated sludge aeration tank and biofilter, so the biological contact oxidation tank has a high volume load

(2) biological contact oxidation method does not need sludge reflux, so there is no problem of sludge bulking, and the operation and management are simple

(3) due to the large amount of biological solids and the completely mixed water flow, the biological contact oxidation tank has a strong adaptability to the sudden change of water quality and quantity

(4) when the organic volume load of the biological contact oxidation tank is high, its f/m remains at a low level and the sludge output is small

6 membrane bioreactor

membrane bioreactor reactor (MBR) is a new wastewater biological treatment process combined with membrane separation and biological treatment technology. Compared with traditional biochemical treatment technology, MBR has the following main characteristics: high treatment efficiency and good effluent quality; Compact equipment and small floor area; Easy to realize automatic control and simple operation management. Since the 1980s, this technology has been paid more and more attention, and has become a hot spot in the research of water treatment technology. At present, membrane bioreactors have been applied in more than ten countries, such as the United States, Germany, France, Japan and Egypt, with a treatment capacity of 6 ~ 13000 m3/d

in recent two years, membrane bioreactor has entered the practical stage in China. The treatment object of MBR system extends from domestic sewage to high concentration organic wastewater and refractory industrial wastewater, such as pharmaceutical wastewater, chemical wastewater, food wastewater, slaughtering wastewater, tobacco wastewater, bean product wastewater, fecal wastewater, yellow swill wastewater, etc. Judging from the current trend, reclaimed water reuse will be the main direction for the promotion and application of MBR in China.

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