SynopsisOn the basis of small capacity wastewater treatment works done in residential clusters and confectionery factories, the treated water reaches column A quality according to QCVN 14:2008/MONRE (BOD<30) mg/l), Nam An company has gradually completed the model of a 6.1-block wastewater treatment tank to meet the needs of local wastewater treatment in residential clusters, high-rise buildings, and processing plants. food….The article aims to share knowledge and experience in calculating, designing, constructing and operating a small-scale wastewater treatment station applying the block tank model 6.1.Synthetic tank architecture 6.1 and wastewater treatment plant technologyThe block tank 6.1 is a tank with many compartments to simultaneously carry out 6 different processes in the domestic wastewater treatment line or food processing wastewater, acacia cake production, etc. with high BOD using microorganisms including microorganisms. including biological treatment process anoxic (anoxic), aerobic (aerotank) and sedimentation, filtration, sterilization, sludge incubation.Depending on the wastewater capacity, we choose the structure of the tank with reinforced concrete or built with solid bricks.The tank can be placed semi-floating, semi-submersible in apartment buildings, food processing factories or fully submerged in high-class villas, can be built in the underground floors of high-rise buildings...There have been many articles on the technology of domestic wastewater treatment with microorganisms, so the article goes straight to the scale of construction and installation of a specific station with a wastewater capacity of Q= 200 m3/day, the type of domestic wastewater. has an average level of organic matter pollution BOD = 250 mg/l.Tank built of reinforced concrete, semi-submersible and semi-floating.Wastewater treatment station 6.1 small capacity to meet the demand of domestic wastewater treatment for an apartment building with about 320 households, each household has an average of 4 people according to the municipal wastewater standard Q0= 150 liters/person .day.The article presents the calculation of the technology and how to properly divide the tank compartments in the 6.1 block tank, the structures to be noted in order for the station to operate stably with the quality of wastewater after treatment reaching column A according to QC 14: 2008/BTNMT, the treated water has residual pressure so that it can be supplied to the irrigation system or discharged into the stormwater drainage system.Domestic wastewater contains pollutants originating from human waste, mainly organic compounds (BOD, COD), N, P compounds, grease and bacteria... .Its basic features are shown in Table 1.Technology for treating domestic wastewater with microorganismsMicrobiological technology is used almost 100% in domestic wastewater treatment.This is a technology that consumes the least chemicals, has the least energy, and has the least secondary emissions compared to other technologies.The domestic wastewater treatment plant uses a 6.1 block tank, applying activated sludge technology with MBC carrier layer, MBBR technology in the tank has a block structure of functional tank compartments into one block.The compound tank consists of the following 6 functional tanks: V1- compartment for conditioning tank, V2- compartment for anoxic tank (Anoxic), V3- compartment for aerobic tank (Aerotank) V4- compartment for lamen settling tank, V5- compartment for storage tank intermediate, V6- prevents sludge incubation.The total volume of functional tank compartments is calculated correctly and sufficiently to ensure thorough treatment of organic and inorganic pollutants, lowering BOD, N, P and heavy ions below the permissible standards according to column A of QCVN 14:2008/BTNMT.Air blower is the most important equipment in domestic wastewater treatment equipment because it works continuously 24/24 hours a day under prolonged blowing mode, so choose many high quality air blowers. have a reasonable capacity to be able to supply gas in many modes, reduce gas supply during the time when wastewater is not generated (midnight to morning) or generated low (office hours) in order to reduce electricity costs and increase life expectancy of equipment.Applying MBBR technique in Aerotank tank to achieve high treatment efficiency, choosing MBC (Moving Bed Carrier) with high porosity to create a high density of adhesion bacteria.MBC microbiological carrier material is made from polyurethane in the form of foam containing calcium carbonate additives with content up to 30% by weight.Increasing the additive component in the microbial carrier aims to create conditions for the development of aerobic autotrophic microorganisms (Nitrifiers), which use inorganic carbon sources as substrates for cell building and digestion. alkali during nitrification.Currently, this type of material can be produced domestically. Therefore, domestically produced MBC materials are used so as not to push up the cost of investment.Working principle of wastewater treatment plant 6.1 Q= 200 m3/dayWaste water from the apartment building flows into the G collection pit, through the garbage screen, flows into the conditioning tank, here are arranged 02 submersible pumps with capacity Q = 10 m3/h, H = 6m (01 running pump, 01 pump). backup) push wastewater into the Anoxic V2 lack of gas treatment compartment.Here the incoming wastewater is mixed with return water from a self-cleaning closed filter system.Part of the organic matter will be reduced to decompose the nitrogen component.The technology chain model is shown in Figure H2.From the V2 tank, the water flows automatically into the Aerotank V3 compartment.At the Aerotank tank, air will be supplied to the bottom of the tank at a depth of 3.2 m above the operating water level.Aerobic bacteria operating in the Aerotank tank decompose all organic matter in the water, lowering the BOD to an acceptable level with BOD < 30 mg/l.Putting MBC microbiological material into Aerotank tank to enhance the ability to store and maintain biomass density in the treatment tank and more importantly increase the cell retention time of slow-growing microorganisms.Changing the ratio of the carrier material in the reaction mass allows flexible application of the surface load of the treatment system, achieving high processing rates per unit volume.The moving carrier avoids clogging and enhances the metabolism of the microorganism attached to the carrier, and also allows more efficient use of oxygen because, when in motion, they prevent and slow down particles. air bubbles come out of the water.From the Aerotank V3 tank, the wastewater automatically flows into the Lamen V4 settling tank to remove the sludge.The activated sludge settles at the bottom of the Lamen clarifier along the sludge push pipe operated by the air supply from the aeration unit, flows into the sludge tank compartment, a part is returned to the Aerotank tank compartment by adjusting the valve arranged on the sludge path. return.In addition, at the bottom of the Lamen tank, there is a sludge discharge pipe to periodically discharge solid sludge to the sludge tank compartment.The water after settling the laminar flows automatically into the V5 tank compartment, the water from the V5 tank compartment is pushed by the booster pump into the self-cleaning closed filter system LK200 including 3 pressure filters D600.This is the difference of station 6.1 compared with conventional wastewater treatment systems that do not have a post-settlement water filter.The filtered wastewater is pushed through the static mixing tank to receive the chlorinated chlorine.In a sealed static mixing tank under pressure, wastewater and chlorine solution go from bottom to top through 3 floors of mixing discs, when coming out of the static mixing tank, the water is of high quality, the turbidity is much lower than the standard, it can be into the pipe to water plants or bring to the water tank for fire fighting.Treated water that meets standard A according to QCVN 14:2008/BTNMT is allowed to be discharged into the environment.Technological calculationCalculate the volume of Aerotank V3 tank:The volume of the Aerotank tank is calculated as follows:V= [Y .Q .Ok .(S0 – S)] : [ X.(1 + Kd.θc)]Where: θ c - mud age: θc = 10 days;Q - wastewater capacity in m3/day: Q = 400 m3/day;X - biomass density: X = 2500 g/m3 ÷ 3500 g/m3;Y - biomass production efficiency: Y = 0.5 ÷ 0.6 g/g (g.biomass/g.BOD);S0 - influent BOD concentration: S0 = 150 ÷ ​​350 mg/l (average ~ 250);S - BOD concentration of wastewater after treatment: S = 30 mgO2/liter = 30 mg/l;Kd - endogenous decomposition constant: Kd = 0.03 0.07 d-1The volume V of the Aerotank tank depends on the organic pollution level of domestic wastewater.If you choose the average to calculate S0 = 250, Kd = 0.06, X = 3000, Y = 0.55, then:V3 tank compartment volume should not be less than 54 m3.Choose V3=60 m3.Calculation of air blower:The amount of oxygen required to clean the BOD is calculated as follows:OC0 = Q x ( S0 – S ) : 1000.F – 1.42.PxWhere: OC0 is the amount of oxygen required under standard reaction conditions at 20oC;Q is the volume of wastewater to be treated (m3/day);S0 is the input BOD5 concentration, S0 = 250 (g/m3);S is the output BOD5 concentration, S = 30 (g/m3) according to grade A wastewater standard;F is the conversion factor from BOD5 to COD or BOD20 usually choose F = 0.6;Px is the excess of cells that are discharged into the microbial sludge.px = Yb x Q x (S0-S) x 10-3 = 0.1 x 200 x (250-30) x 10-3 = 4.4 (kg/day)The station operates under the air blowing mode for 24 hours/day, the amount of oxygen needed in 1 hour is: 2.8 kg.The density of oxygen is ~ 1.4 Kg/m3, so it requires 2.8 : 1.4 = 2 m3 of oxygen gas, corresponding to 9 m3 of air.If using a gas disc with an absorption efficiency of 8%, the amount of gas supplied to the water needs to be: Mk = 9 : 8% = 112.5 m3/h.Install 2 blowers with capacity Q = 120 m3/h, H = 4m (1 backup machine).3.3 Calculation of V4 laminar deposition:Lamen sedimentation compartment area is determined by the formula:Where: Q (m3/h) = 10 (m3/h)W = 50 mm = 0.05 m (lamp slot)h = 1.0 m (height of the lamellar block after tilting 600 )a = 600 (lamp stacking angle) ® cosa = 0.5.The PE laminate has a filter height h = 1.0 m.The depth of the laminar groove d = 25 mm, so the slot W = 25 × 2 = 50 mm = 0.05m, the settling velocity of the floc: U0 = 0.15 mm/s = 0.54 m/h.Substituting the values ​​of the parameters, we have the area of ​​the station's laminar deposition compartment:Lamen deposition compartment installed 3 m3 of PE settling plate with a settling area of ​​3 m2 is satisfactory.V = S( m2) × H(underwater depth - m) = 3 × 3.5 = 10.5 m3.Choose V4 = 30 m3.Calculation of sludge incubation tank V6:The sludge flows into the sludge tank and settles to the bottom.The upper layer of water automatically flows to the conditioning tank.The amount of sludge G collected into the sludge incubator and compaction tank consists of two components, inorganic G1 and organic component G2.Component G1 calculated by total insoluble residue TSS:G1 = (TSS-50) × Q = (220-50) × 200 = 34 000 g = 34 kgThe main component G2 is the residual biomass generated during the biochemical reaction under the prolonged aeration regime, calculated on an average of 0.3 kg/1kg COD input:The amount of sludge G collected in a day is calculated as follows:G = G1 + G2 = 4.4 + 34 = 38.4 kg.G = 38.4 kg/day corresponding to 3.84 m3 of 1% solid mud water.In the incubation tank, the sludge is compressed to a concentration of Ω = 10%.To choose the incubation time Tb = 60 days, a sludge incubation tank with volume:V = 60 × 3.84 × Ω = 23 m3.The volume of V6 must be more than 23 m3.Choose V6= 30 m3.After the incubation period of 60 days, the sludge can be sucked up to dry to be used as microbial fertilizer or sucked by a specialized vehicle and dumped into the landfill.Calculate the volume of the flow-regulating tank V1:The amount of wastewater generated unevenly during the day depends on the peak and low time of domestic water consumption.Choose a disadvantageous period of continuous growth for 8 hours.Choose the highest value of the inharmonious system K = 1.4.Then the volume V1 is determined as follows:V1 = 8 (hours) × 0.4.Q(m3/h) = 8 × 0.4 × (200: 24) = 26.6 m3 .Choose V1= 30 m3Calculate volume of Anoxic V2 anoxic tank:Choose the water retention time at V2 to be 6 hours for the tank to achieve the highest treatment efficiency then:V2 = T(h) x Q(m3/h)/h = 6 x 10 = 60 m3.Choose V2= 60 m3.The volume of this tank can be reduced if an agitator is arranged in the tank.Construction of block tank with reinforced concreteBuilding all functional tank compartments in a large tank with a clearance height of 4.0 m.Flooded height 3.5 m, open space 0.5 m.The functional tank compartments are divided in the block tank by 220 reinforced concrete walls or built with bricks marked with cement mortar #100, plastered with cement mortar #200.The tank compartments have the same submerged volume V=30 m3, then the functional compartments are divided as follows:Air conditioner compartment V1 occupies 1 compartment of 30 m3, installs a submersible sewage pump Q = 10 m3/h, thrust height H = 6 m, Quantity of 2 pumps (1 working pump, 1 backup pump)Anoxic V2 compartment occupies 2 compartments V2 = 2 x 30 = 60 m3.Aerotank V3 compartment occupies 2 compartments V3 = 2 x 30 = 60 m3.Lamen V4 settling compartment occupies 1 compartment V4 = 30 m3.Intermediate compartment V5 = 30 m3.Sludge compartment V6 = 30 m3.The 6.1 block tank needs an area of ​​about 80 m2.The area of ​​​​the house to place the wastewater treatment equipment needs to be about 60 m2, which is used to install the self-cleaning closed filter system, the blower, the metering pump, the control cabinet and the equipment: The general electrical cabinet and the electrical control cabinets for the equipment. wastewater treatment;Cluster of 2 blowers with capacity Q = 110 m3/h;Cluster of 2 booster pumps Q = 12 m3/h, H = 20m;Cluster of self-cleaning filter equipment LK400 capacity Q = 200 m3/day including 3 pressure filters D600;Disinfectant chlorine supply equipment includes metering pump 0-11 l/h and tank of Javen solution V= 500 liters.The total area required by the station is not large, about 300 m2, see Figure 3.Points to note in the construction and operation of wastewater treatment systemsThe main shaft gas pipeline is not flooded, so the SUS 304 stainless steel pipe should be used.The distribution pipes for supplying and collecting wastewater in anoxic tanks must be arranged reasonably and conveniently for the treatment of clumps causing blockages.Lamen sedimentation tank needs a manipulator, the bottom of the sludge collection tank must be sloped 60 degrees, additionally placedSubmersible sewage pump here to pump circulating water to Aerotank tank with capacity Q = 3m3/h, pushing pressure H = 6m.The sus304 stainless steel mesh frame blocks the carrier material in the compartments of the Aerotank tank compartment, the frame size is 1m × 1m, the sus 304 stainless steel mesh is 5 × 5 × 1mm.Arrange the water return line after the closed filter to self-wash before the chlorine filling head.The filtered water returns to the anoxic tank, creating a denitrification process and an amount of organic matter is consumed in this process.The return water flow after the filter depends on the power selection of the booster pump, increasing the pump capacity will significantly increase the treatment efficiency of the system, which has special significance when treating wastewater. from food processing plants.Build the sludge tank compartment adjacent to the conditioning tank compartment and open the overflow window to create overflow from the sludge incubation tank compartment to the conditioning tank compartment to collect residual water after settling of the sludge incubation tank compartment.In fact, the wastewater treatment plant 6.1 is capable of treating very high BOD wastewater generated from the confectionery factory.The image of wastewater station 6.1 built for a confectionery factory is shown in Figures 4 and 5.The station has been operating stably for many years, the treated wastewater meets column A standards according to QCVN 14:2008/BTNMT.Nguyen Thanh HungChairman of Nam An Hi-tech Environment Company© Vietnam Electronic Cities and Environment TCAgency of Vietnam Urban Environment and Industrial Zones IndustryEditor-in-Chief: Dr. LS. Dong Xuan ThuChairman of the Board of Directors: Dr.Tran Quang DaoJournalist Nguyen Thi Anh HongOperation License of Electronic Newspaper No: 182/GP-BTTTT of the Ministry of Information and CommunicationsAdvertising contact: 0912 233 702Editorial office: 17th Floor, Office Area, C1 Thanh Cong Building, Ba Dinh, Hanoi.Newsroom Information - RssBanner Quotes - Online PR Quotes - Print QuotesPlease cite "moitruongvadothi.vn" when you redistribute information from this website.