The purpose of further advanced treatment is to remove the secondary (enhanced) organic pollutants that are not completely removed, the combination of SS and chroma, odor and minerals, and other common advanced treatment technologies include coagulation precipitation, dielectric filters (including biological filtration) Pool), membrane treatment and oxidation, etc. This tutorial will also include membrane bioreactor (MBR) technology in deep processing technology.

1. Coagulation and sedimentation technology

A method of using a coagulant to coagulate suspended particles and colloidal substances in water to form flocs, and then remove the flocs to settle. Mixed coagulant reaction can use pipeline or mechanical stirring together, etc. Appropriate salt and iron-aluminum salt coagulant choice, add organic polymer coagulant aid if necessary. The precipitation facilities are mainly advection, vertical flow, radial flow and inclined plate (tube) sedimentation tanks, and a clarifier can also be used to remove cotton wool.

(1) (Scope) is suitable for the secondary treatment of urban sewage \\//secondary enhanced treatment depth, but it can also be used as a pretreatment technology to ensure the subsequent treatment process and stable operation.

(2) (Technical Features) Economical, convenient, wide application range, turbidity, phosphorus, and obvious color have a better removal effect.

(3) (Operating parameters) Water quality and coagulant related to the amount of coagulant, the general operating conditions are suitable for 2-10 mg\\ / L (iron or aluminum); the mixing reaction time is suitable for 10 to 15 minutes, and the precipitation time is suitable 60-120 minutes.

(4) (Impact) and secondary treatment sewage water, the turbidity of coagulation sedimentation wastewater can reach 1-5 Nanda; ODCr removal rate is about 10-30%, according to the concentration of total phosphorus and sediment, the removal rate of total phosphorus is usually 40-80%.

2, media filtration technology

includes sand filter, filter cloth filtration, such as SS removal technology, this tutorial will also include biological filter in the filter medium.

2.1 sand filter

Use a certain particle size distribution of quartz sand and other inorganic media to filter and intercept suspended and colloidal substances.

(1) (range) is suitable for coagulation sedimentation water turbidity removal water advanced treatment or other requirements. The secondary treatment of municipal sewage \\//secondary enhancement can be used to treat low-turbidity water with micro-flocculation filtration. Commonly used sand filters have v-type filters, and so on.

(2) (technical characteristics) is simple, economical, practical, stable and reliable operation, including micro-flocculation-filtration of phosphorus has a certain influence.

(3) (Operational parameters) The operational parameters such as filter particle diameter, layer thickness and filtration speed are related to the form of filtration. When using a v-shaped filter, the thickness of the filter layer of the uniform filter material should be about 1.0-1.5 meters, and the filter speed should be 4 to 8 m \\ / h, depending on the water turbidity return cycle.

(4) (Impact) Sand filtration water turbidity; micro-flocculation-filtration to remove phosphorus and water concentration and flocculant dosage, removal rate is usually 20-50%.

(5)(Note) The use of microflocculation, filtration, design, and improper operation will shorten the filter backwash cycle and cause the turbidity of the water.

2.2 filter cloth filtration

Use a filter cloth with a certain pore size to filter and remove the total suspended solids. Filter cloth filtration technology Surface filtration technology can replace traditional deep bed filtration.

(1) (range) is suitable for coagulation sedimentation water turbidity removal water advanced treatment or other requirements.

(2) (Technical characteristics) Energy saving, generally 1 \\ \ / 3 conventional energy consumption water recoil air filter; small filter head, small footprint, easy to maintain and use.

(3) (Operating parameters) The hydraulic load should be 6-16 m3 \\/m²?H(), the filter plate with a diameter of 0.90-3.00 meters, and the speed of the backwash filter plate is usually 0.5-1.0 \/min.

(4) (Impact) The removal rate of SS can reach more than 50%.

(5)(Note) When the SS is too high or the adhesion is strong, the filter cloth is easily contaminated and congested.

2.3 Biological Filter

Use surface-attached biofilm filter material and its removal of nitrogen and organic pollutants and suspended solids. According to different treatment goals, it can be divided into biological aerated filter and denitrification filter.

(1) (Scope) is suitable for the secondary treatment of municipal sewage \\ \/ the advanced treatment of secondary enhanced treatment water, and can also be used for the post-treatment of water ozone oxidation. The biological aerated filter is suitable for the removal of nitric acid from ammonia and the denitrification filter is suitable for removal.

(2) (Technical Features) Removal of ammonia nitrogen (or), total nitrogen and organic pollutants.

(3) Biological aerated filter (operating parameters), the purpose is to remove 0.2--0.6 kg of ammonia nitrogen, the total volume load / / ammonia nitrogen (m3 Liao? D), the appropriate filtration speed 3-6 m \\ \/ h, the supply should be about 70 cubic meters \\ / kg of ammonia nitrogen; when treating the ozone oxidation of the water, the appropriate filtration speed is 4 to 10 m \\ / h. The volume load of the denitrification filter is usually 1-1.5 kg of nitrate nitrogen \\ / (m3 Liao? D), the appropriate filtration speed is 5-8 m \\ / h, and the additional carbon source is based on the removal of nitrate ( CODCr \\ \/ N) 5-6 times.

(4) (Impact) The removal rate of ammonia nitrogen in the secondary treated sewage water and biological aerated filter can reach more than 90%, the removal rate of CODCr can reach 10-30%, and the effluent SS is generally 15 mg / L or less; ozone Oxidized water becomes water, which can effectively remove the ozone oxidation of small molecular organic compounds, such as aldehydes, etc.; the removal rate of nitrate in the denitrification filter mainly depends on the amount of added carbon source, generally 50-90%.

(5) (Note) The nitrification efficiency of the biological aerated filter will decrease when the water temperature is low; the high carbon source for denitrification will add a filter to control the demand, the supply will produce the accumulation of nitrite, and too much will lead to a higher organic content. Attention should be paid to the clogging problem caused by biological growth of the filter bed; in principle, nitrogen removal should be done first in the secondary enhanced treatment unit.

3, membrane treatment technology

The membrane treatment technology in this guide includes solid-liquid separation technology based on microfiltration and ultrafiltration, and technology based on reverse osmosis desalination and soluble pollutant removal. Specifically include: membrane bioreactor (MBR) technology, microfiltration / ultrafiltration membrane filtration technology; reverse osmosis (RO) technology.

3.1 Membrane Bioreactor

membrane separation technology combined with activated sludge biological treatment unit, replacing the traditional two ponds, membrane filtration technology in water treatment. Common component types mainly include plates and two kinds of hollow fibers.

(1) (Scope) is applicable to urban sewage water treatment.

(2) (Technical Features) It can overcome the shortcomings of the traditional activated sludge method, the loss of sludge expansion, high volume load, stable treatment effect, and overall water quality is better than traditional biological treatment technology.

(3) (Operating parameters) The membrane flux is usually 10 to 20 l \\ \/m²?H(), the appropriate operating pressure is less than 0.05 Mpa, and the gas-water ratio is suitable for 10 to 30.

(4) (Impact) Wastewater CODCr <30 mg\\ \/ L, turbidity <1 Nanda.

(5) (Note) Prone to membrane pollution, high-demand operation management, maintenance and chemical cleaning are quite complicated, and regular cleaning is required for online and offline cleaning. The replacement cycle of hollow fiber membrane modules is generally 3-5 years. The replacement cycle is 5-8 years, and the replacement cost of the membrane module needs to be considered; due to the membrane flux, the adjustment margin in the face of hydraulic shock load is small, the sludge concentration in the reactor is high, and the membrane module is damaged. The water quality is safe.

3.2 microfiltration \\ \/ ultrafiltration membrane filtration

Using ultrafiltration membrane microfiltration membrane or removing students and colloidal substances processing technology, mainly including two application modes of external type and immersion. Common component types mainly include three plates, tubes and hollow fibers.

(1) (Scope) is suitable for the depth of the secondary treatment of urban sewage \\//the depth of the secondary enhanced treatment.

(2) (Technical features) It can replace the traditional precipitation-filtration process, and has the ability to effectively remove suspended solids and colloidal substances. The water quality is filtered by traditional media, has a smaller footprint, and has a high degree of automation. It is suitable for precipitation and filtration technology. Upgrade of urban sewage treatment infrastructure.

(3) (Operation parameters) Operation parameters and membrane filtration method. External type: proper working pressure 0.2 Mpa, or less flux suitable for 40-70 l \\ \/m² H(), proper reflux cycle 30 to 60 minutes; immersion: operating pressure should be 0.05 Mpa, or less pass The amount is suitable for 30-50 l \\ \/ square meter? H(), and the appropriate reflux cycle is 30 to 60 minutes.

(4) (impact) is about 5-30%, CODCr removal rate and turbidity <0.2 Nanda, water recovery rate is 90% or higher.

(5)(Note) The water immersion method uses negative pressure suction, and the operating cost is 20-50% lower than that of the external type; the external type and water flux are large, and the same treatment scale uses less membrane area, which saves investment. On-line and off-line regular chemical cleaning, the replacement cycle of membrane modules is about 3-5 years.

3.3 reverse osmosis technology

Membrane separation technology that only uses water, not through reverse osmosis membrane solute removal of water-soluble materials.

(1) (Scope) is suitable for the production of reclaimed water with special requirements for soluble inorganic salts and organic content.

(2) (Technical characteristics) The water quality is good, and the organic matter and inorganic salt content is much lower than other membrane water treatment technologies, which can increase the water production based on reverse osmosis water recovery.

(3) (operating parameter) water pollution index (SDI15) <3, operating pressure is 2.0 Mpa or less.

(4) (Impact) The output of secondary reverse osmosis water can exceed 70%, the level rate of reverse osmosis desalination system is greater than 95%, and the desalination rate of secondary reverse osmosis is greater than 97%.

(5) (Note) Reverse osmosis pretreatment requirements are high, generally ultrafiltration or microfiltration pretreatment is required, and disposable safety filters (usually 5 micron filters are used); reverse osmosis water has a low pH value and requires According to the requirements of water quality, there is a lot of water, and the content of inorganic salts and organic matter in flushing water is high, and its disposal needs to be fully considered; the use of reverse osmosis membranes in sewage treatment is prone to membrane pollution problems, requiring 2-6 membrane chemical cleanings, 3- Replace the membrane module within 5 years; in actual operation, the water pump cannot be used, and appropriate measures must be taken for low-temperature insulation in winter.

4, oxidation technology

Strong oxidants, such as the use of ozone water color, odor and toxic, harmful and other organic matter oxidation removal technology, according to the water quality and water quality requirements can also be ozone, hydrogen peroxide, ultraviolet-hydrogen peroxide and other advanced oxidation technology.

4.1 Ozone oxidation

Use ozone as an oxidant to remove oxides in water for color, odor and toxic and harmful organic matter.

(1) (Scope) is mainly used for water color, odor, toxic and harmful organic substances and the secondary treatment of municipal sewage etc.Suitable \\ \/the depth of the secondary enhanced water treatment.

(2) Website preparation (technical features), simple operation, can comprehensively improve water quality and strengthen the removal of pathogenic microorganisms.

(3) (Operation parameters) The ozone dose is suitable for 3-8 mg\\ \/ L, and the appropriate time of contact is 5-10 minutes.

(4) (impact) The color, odor and toxic and harmful organic compounds contain unsaturated bonds and have a significant effect on removing unsaturated bonds. The color of water is usually below 10 degrees, which can effectively remove odors and reduce the impact of biological toxicity.

(5) (Note) If there is strong oxidation, relevant facilities should be used to contact ozone anti-oxidant materials; ozone is toxic, the smell is unpleasant, and the damage must be equipped with exhaust devices, and measures should be taken to prevent ozone leakage. Post-biological filtration should be adopted Technology, such as biological activated carbon filter to remove ozone oxidation intermediate (aldehyde materials, etc.).

4.2 ozone, hydrogen peroxide

Use ozone and hydrogen peroxide coupling technology to remove oxides of water color, odor, toxic and harmful organic matter.

(1) (Scope) is suitable for the depth of the secondary treatment of urban sewage \\//the depth of the secondary enhanced treatment.

(2) (Technical characteristics) Ozone oxidation with stronger oxidation ability than hydroxyl radicals; flexible operation mode, ozone oxidation, independent-hydrogen peroxide combination can be selected according to the actual situation, the combination method used can be at multiple levels After adding hydrogen peroxide to the ozone contact pool, compared with UV-hydrogen peroxide technology, it is not affected by turbidity and has a shorter reaction time.

(3) (Operating parameters) The ozone dosage is suitable for 3-8 mg\/L, the ratio of hydrogen peroxide and ozone dosage is generally 0.3-0.5 (mass ratio), and the contact time should be greater than 5 minutes.

(4) (Effect), color, smell and removal effect are very lonely with ozone oxidation, and the oxidation ability of loneliness is stronger than that of ozone oxidation.

(5) (Note) It is the same as ozone oxidation, you need to pay attention to ozone oxidation and toxicity; hydrogen peroxide is easy to decompose at high temperature, and storage and transportation should be safe; there may be residual hydrogen peroxide, hydrogen peroxide in water Content requirements, activated carbon bed hydrogen peroxide decomposition should be used. See http:\\ \/ \\ \/ www.dowater.com for more specific technical documents.

4.3 UV-hydrogen peroxide

Using UV-hydrogen peroxide coupling technology to remove oxides of water color, odor, toxic and harmful organic matter.

(1) (Scope) is suitable for the depth of the secondary treatment of urban sewage \\//the depth of the secondary enhanced treatment.

(2) (Technical Features) The ability to use oxidized hydroxyl radicals to oxidize and disinfect at the same time.

(3) (operating parameters) the effective dose of ultraviolet light or 20 mj \\ / cm2, the amount of hydrogen peroxide is suitable for 3-8 mg\\ / L, the contact time should be more than 30 minutes.

(4) It has stronger oxidizing power than ozone (effect), and has a certain color in addition to the olfactory effect.

(5) (Note) SS and UV lamp dirt on the water surface can easily reduce the efficiency of UV disinfection; the life of the UV lamp is generally one year, and it can produce heavy metal waste pipes. Take corresponding safety measures.