10 Process Principles of Wastewater Treatment
1. Purification mechanism of biofilm method
1.1 Biofilm consists of aerobic and anaerobic layers, the degradation of organic matter mainly occurs in the aerobic layer.
1.2 Oxygen in the air is dissolved in the flowing water layer, from where it passes to the biofilm through the attached water layer for microorganisms to use for respiration, and the organic matter in the sewage passes to the attached water layer from the flowing water layer and then enters into the biofilm and is degraded through the metabolism activities of the bacteria, so that the sewage will be purified gradually in its flowing process, and the microorganism’s metabolites such as water enter into the flowing water layer through the attached water layer and are The metabolites of microorganisms, such as water, enter the flowing water layer through the attached water layer, and are discharged along with it, while carbon dioxide and the decomposition products of the anaerobic layer, such as H2S, NH3, and gaseous metabolites, such as CH4, escape from the water layer and enter into the air.
1.3 When the anaerobic layer is not thick, it maintains a certain balance and stability with the aerobic layer, and the aerobic layer can maintain the normal purification function, but the anaerobic layer is gradually thickened and reaches a certain level, the metabolism products are gradually increased, and in the process of their escape, the aerobic ecosystem of the stabilization of the state has been destroyed, and weakened purification function.
2. Main features of biofilm treatment method
2.1 Microbial phase characteristics: (1) participate in purification reaction microbial diversity (2) biological food chain is long (3) can survive a long generation of microorganisms (4) segmented operation in the predominant species
2.2 treatment process: (1) water quality, water changes have a strong adaptability (2) sludge settling performance is good, suitable for solid-liquid separation (3) to deal with low concentrations of sewage (4) easy to maintain the operation, energy saving.
3. Aeration pool biofilter process and features
Process: the bottom of the pool is equipped with a support layer, the upper part of the filler as a filter material, set up in the support layer of the aeration of air tubes and air diffusion devices, treated water collector pipe also used as a backwash water pipe is also set in the support layer. The raw sewage being treated enters the tank from the upper part of the tank and passes through the filter layer composed of filler layer, forming a biofilm on the surface of the filler formed by the microorganisms inhabiting the formation of the biofilm. In the sewage filter filter layer more at the same time, from the lower part of the pool through the air pipe to the filter layer for aeration, the air from the gap between the filler rises, and the downstream sewage contact, the oxygen in the air transferred to the sewage, to the microorganisms on the biofilm to provide sufficient dissolved oxygen and rich in organic matter, in the microorganisms of the metabolism, the organic pollutants are degraded, sewage is treated.
Features: (1) gas-liquid-solid three-phase contact, high volumetric loading of organic matter, short hydraulic retention time, low capital investment, O2 transfer efficiency, low power offset (2) can retain SS, shedding of biofilm, do not need to sedimentation tanks, occupies a small area (3) 3-5mm filter media, large surface area, microorganisms adsorption capacity (4) strong impact resistance (5) do not need sludge reflux, no sludge expansion, such as backwashing If the backwash is fully automated, the maintenance and management is also convenient. (6) large biomass in the pool, and then due to the retention effect, the sewage treatment effect is good.
4. What is biofilm method? What are the advantages compared with activated sludge method?
A: Biofilm method is the use of bacteria and fungi, a class of microorganisms and protozoa, after a class of micro-animals attached to the filter media or some carrier growth and development and the formation of membrane biological sludge (biofilm) to treat sewage treatment of a biological treatment technology.
Advantages: Due to the large number of microorganisms on the biofilm, the ecosystem formed is more stable than the activated sludge system. The food chain on the biofilm is longer than that of activated sludge, and the amount of sludge is less than that of activated sludge system, which reduces the cost of sludge follow-up treatment. Due to the longer age of sludge, the biofilm can survive long generation time microorganisms like nitrifying bacteria and nitrosifying bacteria, thus it has certain digestive function. He has strong adaptability to water quality and water quantity changes, even if a period of time to interrupt the water intake, the biofilm will not have a fatal impact, easy to recover after the water, while the activated sludge needs a longer time to recover. Due to the high inorganic composition of the biofilm, the specific gravity is larger, his sludge sedimentation is good. Easy solid-liquid separation. Biofilm method is able to deal with low concentration wastewater, while activated sludge is not suitable for dealing with low concentration of sewage, if the BOD is lower than 50-60mg/L for a long time, it will affect the formation of sludge floc. Compared to activated sludge, biofilm is easy to maintain movement, energy efficient and has low power costs. If run properly, the biofilm method can also realize synchronous nitrification denitrification reaction.
5. Stabilization pond features and advantages and disadvantages
Characteristics: (1) generally not artificially strengthened (2) similar to the self-purification process with the water body (3) long residence time (4) through the combined effect of microorganisms + aquatic organisms of a variety of organisms, so that organic degradation, and thus purify the wastewater (5) purification process, including – aerobic, parthenogenetic, anaerobic three states (6) DO comes from the photosynthesis ( (7) applicable to a variety of sewage (8) applicable to a variety of climatic conditions (9) can be realized from primary to secondary to the depth of the whole process of treatment technology, generally equivalent to secondary
Advantages: (1) investment, simple engineering (2) able to sewage resources, agricultural irrigation (3) low energy consumption
Disadvantages: (1) covers a large area (2) purification effect is controlled by natural factors (3) the impact on groundwater (4) sanitary conditions
Poor sanitation.
6. Stabilization ponds on the purification of sewage
(1) Dilution: the role of wind, water and pollutant diffusion ___ physical processes (2) sedimentation and flocculation: SS natural sedimentation, small SS, microbial flocculation (3) metabolism of aerobic microorganisms: heterotrophic aerobic bacteria and parthenogenetic bacteria (4) anaerobic microorganisms metabolism: parthenogenetic ponds on the bottom of the pond + anaerobic ponds within the DO = 0 hydrolysis stage, hydrogen production and production of acetic acid, methanogenesis stage (5) Role of plankton: main role of algae 。。。。 Oxygen supply; main function of plankton 。。。。 Swallow free bacteria to clarify water. Secretion of mucus that produces bioflocculation; Benthic organisms —— Shaking mosquitoes ingest algae or bacteria from the sludge layer. Reduces the sludge layer; fish —— prey on micro aquatic animals and fouling. (6) Role of vascular plants in water; a Absorption of N and P. b Enrichment of heavy metals; c Oxygenation of pond water; d. Rhizomes provide a growth medium for cells.
(7) There is a change in the pH value of pond water stabilizing the pond’s purification of sewage; CO2+H2O—-H2CO3——HCO3-+H+
CO3-+H2O————-HCO3-+OH- During the day light and action is strong, CO2 is consumed, the equilibrium of one equation is shifted to the left and the equilibrium of two equilibrium is shifted to the right, so PH rises, and at night the light and action stops, CO2 accumulates in the right row, and the equilibrium of one equilibrium is shifted to the right and the equilibrium of two equilibriums is shifted to the left PH decreases.
8. Purification mechanism of land treatment system
Physical filtration — the pores between soil particles have the function of retaining and filtering out SS in water. 2, physical adsorption and physicochemical adsorption of van der Waals force metal ions (sub exchange, adsorption and chelation) 3, chemical reaction and chemical precipitation —— metal ions and some components in the soil. 4, microbial metabolic effects
9. Principles and processes of biological nitrogen and phosphorus removal
In untreated fresh sewage, the main forms of nitrogenous compounds exist are organic nitrogen and ammonium nitrogen, generally dominated by organic nitrogen, ammonification reaction is organic nitrogen compounds in the ammonia bacteria, the decomposition of the process of conversion to ammonium nitrogen. The reaction is: RCHNH2COOH+O2————–RCOOH+CO2+NH3 Nitrification reaction is under the action of nitrifying bacteria. Ammoniacal nitrogen is further oxidized to form nitrate nitrogen process, the reaction formula is NH4+2O2——NO3-+H2O+2H+-△F (△F=351kj) Nitrification should maintain aerobic conditions, and the mixture should not be too high in organic matter. Denitrification reaction when nitrate ammonia and nitrite nitrogen in the denitrifying bacteria, is reduced to gaseous nitrogen process. In the denitrification process, nitrate nitrogen through the metabolic activities of denitrifying bacteria, there may be two transformation pathways, namely, assimilation denitrification, and ultimately the formation of organic nitrogen compounds, which become an integral part of the bacterial body, and the other is heterogeneous denitrification, the final product is gaseous nitrogen.
Process: activated sludge denitrification traditional process: sewage into the first aeration tank to remove BOD, COD, so that organic nitrogen is converted to form NH3 NH4, to complete the ammonia process. After precipitation, the sewage into the second nitrification aeration tank, nitrification reaction, so that NO3- —–N, nitrification needs to consume alkalinity, so to throw alkali, in order to prevent PH decline. The third extreme denitrification reactor, here in anoxic conditions, NO3- ——–N reduction to gaseous N2, and escape to the atmosphere, at this level should take anaerobic —- anoxic alternating mode of operation, the carbon source can be cast methanol can also be introduced into the original sewage as a carbon source.
Anoxic —– aerobic activated sludge denitrification and phosphorus removal system: nitrification reactor has been fully reacted part of the digestive solution back to the denitrification reactor, denitrification reactor denitrification bacteria in the wastewater as a source of carbon in the organic matter, to the return of oxygen in the nitrate as a receptor for respiration and life activities, nitrate nitrogen is reduced to gaseous nitrogen, do not need to be added to the carbon source.
10. The principle and process of biological phosphorus removal
Biological phosphorus removal is the use of phosphorus removal bacteria, a class of microorganisms, can be excessive, in quantities exceeding their physiological needs, from the outside are ingested phosphorus, and phosphorus in the form of polymerization of storage in the body of the bacterium, the formation of high-phosphorus sludge, exclude the system outside the road from the wastewater phosphorus removal effect.
| Phosphonates Antiscalants, Corrosion Inhibitors and Chelating Agents | |
| Amino Trimethylene Phosphonic Acid (ATMP) | CAS No. 6419-19-8 |
| 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid (HEDP) | CAS No. 2809-21-4 |
| Ethylene Diamine Tetra (Methylene Phosphonic Acid) EDTMPA (Solid) | CAS No. 1429-50-1 |
| Diethylene Triamine Penta (Methylene Phosphonic Acid) (DTPMPA) | CAS No. 15827-60-8 |
| 2-Phosphonobutane -1,2,4-Tricarboxylic Acid (PBTC) | CAS No. 37971-36-1 |
| 2-Hydroxy Phosphonoacetic Acid (HPAA) | CAS No. 23783-26-8 |
| HexaMethyleneDiamineTetra (MethylenePhosphonic Acid) HMDTMPA | CAS No. 23605-74-5 |
| Polyamino Polyether Methylene Phosphonic Acid(PAPEMP) | |
| Bis(HexaMethylene Triamine Penta (Methylene Phosphonic Acid)) BHMTPMP | CAS No. 34690-00-1 |
| Hydroxyethylamino-Di(Methylene Phosphonic Acid) (HEMPA) | CAS No. 5995-42-6 |
| Salts of Phosphonates | |
| Tetra sodium salt of Amino Trimethylene Phosphonic Acid (ATMP•Na4) | CAS No. 20592-85-2 |
| Penta sodium salt of Amino Trimethylene Phosphonic Acid (ATMP•Na5) | CAS No. 2235-43-0 |
| Mono-sodium of 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid (HEDP•Na) | CAS No. 29329-71-3 |
| (HEDP•Na2) | CAS No. 7414-83-7 |
| Tetra Sodium Salt of 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid (HEDP•Na4) | CAS No. 3794-83-0 |
| Potassium salt of 1-Hydroxy Ethylidene-1,1-Diphosphonic Acid (HEDP•K2) | CAS No. 21089-06-5 |
| Ethylene Diamine Tetra (Methylene Phosphonic Acid) Pentasodium Salt (EDTMP•Na5) | CAS No. 7651-99-2 |
| Hepta sodium salt of Diethylene Triamine Penta (Methylene Phosphonic Acid) (DTPMP•Na7) | CAS No. 68155-78-2 |
| Sodium salt of Diethylene Triamine Penta (Methylene Phosphonic Acid) (DTPMP•Na2) | CAS No. 22042-96-2 |
| 2-Phosphonobutane -1,2,4-Tricarboxylic Acid, Sodium salt (PBTC•Na4) | CAS No. 40372-66-5 |
| Potassium Salt of HexaMethyleneDiamineTetra (MethylenePhosphonic Acid) HMDTMPA•K6 | CAS No. 53473-28-2 |
| Partially neutralized sodium salt of bis hexamethylene triamine penta (methylene phosphonic acid) BHMTPH•PN(Na2) | CAS No. 35657-77-3 |
| Polycarboxylic Antiscalant and Dispersant | |
| Polyacrylic Acid (PAA) 50% 63% | CAS No. 9003-01-4 |
| Polyacrylic Acid Sodium Salt (PAAS) 45% 90% | CAS No. 9003-04-7 |
| Hydrolyzed Polymaleic Anhydride (HPMA) | CAS No. 26099-09-2 |
| Copolymer of Maleic and Acrylic Acid (MA/AA) | CAS No. 26677-99-6 |
| Acrylic Acid-2-Acrylamido-2-Methylpropane Sulfonic Acid Copolymer (AA/AMPS) | CAS No. 40623-75-4 |
| TH-164 Phosphino-Carboxylic Acid (PCA) | CAS No. 71050-62-9 |
| Biodegradable Antiscalant and Dispersant | |
| Sodium of Polyepoxysuccinic Acid (PESA) | CAS No. 51274-37-4 |
| CAS No. 109578-44-1 | |
| Sodium Salt of Polyaspartic Acid (PASP) | CAS No. 181828-06-8 |
| CAS No. 35608-40-6 | |
| Biocide and Algicide | |
| Benzalkonium Chloride(Dodecyl Dimethyl Benzyl ammonium Chloride) | CAS No. 8001-54-5, |
| CAS No. 63449-41-2, | |
| CAS No. 139-07-1 | |
| Isothiazolinones | CAS No. 26172-55-4, |
| CAS No. 2682-20-4 | |
| Tetrakis(hydroxymethyl)phosphonium sulfate(THPS) | CAS No. 55566-30-8 |
| GLUTARALDEHYDE | CAS No. 111-30-8 |
| Corrosion Inhibitors | |
| Sodium salt of Tolyltriazole (TTA•Na) | CAS No. 64665-57-2 |
| Tolyltriazole (TTA) | CAS No. 29385-43-1 |
| Sodium salt of 1,2,3-Benzotriazole (BTA•Na) | CAS No. 15217-42-2 |
| 1,2,3-Benzotriazole (BTA) | CAS No. 95-14-7 |
| Sodium salt of 2-Mercaptobenzothiazole (MBT•Na) | CAS No. 2492-26-4 |
| 2-Mercaptobenzothiazole (MBT) | CAS No. 149-30-4 |
| Oxygen Scavenger | |
| Cyclohexylamine | CAS No. 108-91-8 |
| Morpholine | CAS No. 110-91-8 |
| Other | |
| Sodium Diethylhexyl Sulfosuccinate | CAS No. 1639-66-3 |
| Acetyl chloride | CAS No. 75-36-5 |
| TH-GC Green Chelating Agent (Glutamic Acid,N,N-diacetic Acid, Tetra Sodium Salt) | CAS No. 51981-21-6 |