The chemical process of the brass strip When the total cyanide content is greater than 100mg / L, the pH value is well controlled between 12 and 13. At this time, if the ORP value of the wastewater is less than 300mV, the sodium hypochlorite solution is automatically added to the wastewater ORP value of 300mV Stop feeding, oxidize CN- to CNO- with a delay of 15min; then add sulfuric acid to adjust the pH to 6.5 ～ 7.0, and then add sodium hypochlorite solution, stop feeding when the wastewater ORP value is 450mV, and delay 15min to oxidize CNO- to Carbon dioxide and nitrogen; then the water is automatically discharged into the mixing pool, and the entire process takes about 3 hours. (1) When the total cyanide content is greater than 100mg / L, the pH value is well controlled between 12 and 13, at this time, if the ORP value of the wastewater is less than 300mV, it is automatically added Sodium hypochlorite solution, stop feeding when the wastewater ORP value is 300mV, delay the 15 minutes to oxidize CN- to CNO-; then add sulfuric acid automatically to adjust the pH value to 6.5 ～ 7.0, and then automatically add sodium hypochlorite solution, stop when the wastewater ORP value is 450mV Feed, delay CNO- into carbon dioxide and nitrogen with a delay of 15min; then automatically discharge water into the mixing tank, the whole process is about 3h. (2) Chromium-containing wastewater reduction Chromium-containing wastewater is pumped into the reduction equipment. Under the control of the pH / ORP instrument, the wastewater is automatically dosed with acid (if the pH of the input water is less than 3, the alkali is adjusted) to adjust the pH to 3, such as When the ORP value of wastewater is greater than 350mV, a reducing agent is automatically added to make the ORP value equal to 350mV, and the Cr6 + is reduced to Cr3 + after a delay of 25min, and then the wastewater is automatically discharged into the mixed pool. (3) Degreasing of oily wastewater The oily wastewater is pumped into the degreasing reactor. After demulsifier is added for 30min, the oil scraper is started to scrape off the floating oil, and the lower layer liquid is regularly discharged into the mixing pool by the metering pump. (4) Acid-base heavy metal mixed wastewater Acid-base heavy metal mixed wastewater is pumped into the front pH adjusting tank. The wastewater is automatically added with alkali under the control of pH instrument. After two-stage pH adjustment, the pH is adjusted to 8.5 ～ 9.0 to form metal ions. At the copper strip same time, calcium chloride solution is added to generate hydroxyapatite to achieve the purpose of phosphorus removal. The chemically treated wastewater enters the dosing chamber of the inclined tube settler. (5) After the chemically treated wastewater enters the inclined tube sedimentator dosing chamber, polymerized ferric sulfate and polyacrylamide are added as flocculants and coagulant aids, and then it flows through the inclined tube sedimentation area, and the upper clear water flows into the clear water chamber, and the bottom sludge Drain into the sludge tank regularly. (6) The effluent of the sand filtration and backwash sedimentation tank also contains a small amount of fine particles, so it needs to be further separated. The wastewater in the clean water chamber is pumped into the pressure type double-layer filter material filter, in which solid suspended matter is retained by the filter material. Clean water passes through the filter layer. When the amount of trapped sludge reaches the specified level, the filter layer resistance rises to the specified pressure. At this time, compressed air and clean water in the clear water are automatically used for scrubbing and backwashing, and the backwash sewage is returned to the mixed pool. (7) The water from the cation exchange column sand filter automatically overflows into the cation exchange column. The cation exchange column uses a special cation resin to adsorb the remaining metal ions to ensure that the metal ions reach the first-level emission standard. (8) Later pH adjustment Because the wastewater is weakly acidic after passing through the cation exchange column, the discharged wastewater needs to be monitored by the pH value before entering the biological contact oxidation tower. This process uses automatic control technology to adjust the pH value automatically. Dosing, automatic alarm when exceeding the standard, to ensure that the pH value is controlled between 6-9. (9) Biological contact oxidation Biological contact oxidation belongs to the biofilm method. With the help of a biofilm attached to an elastic filler, wastewater flows in the elastic filler penetrating up and down, making extensive contact with the biofilm, and aerobic conditions with microorganisms on the biofilm. The metabolism function removes organic matter in the wastewater to purify the wastewater; the effective contact time of the wastewater in the tower is 5 hours, and a porous air pipe is connected to the roots blower at the bottom. In order to prevent foam overflow in the tower, the liquid level in the tower should be lower than the top of the tower The height is less than 1m; biofilm cultivation is required before operation. The hanging strains use domestic waste sewage or a mixed solution of domestic waste sewage and activated sludge. After 5 days of suffocation, the sludge becomes yellow-brown, and the surface sludge changes from anaerobic. The state is changed to aerobic state, and continuous water treatment can be performed. (10) The biological sludge falling off the contact oxidation tower pond contains a large number of air bubbles, which is suitable for separation by air flotation; adding polyferric sulfate and polyacrylamide as flocculants in the reaction chamber before the flotation to facilitate solid-liquid separation. The pressure of the dissolved gas tank is automatically controlled between 0.3 and 0.5 MPa. (11) The activated carbon adsorber takes into account the control of the total amount of COD emissions. The water from the air flotation tank is pressurized and enters the activated carbon adsorber to further remove COD and other pollution in the wastewater. (12) The sludge from the sludge dewatering sludge tank is sent to a filter press by a pneumatic diaphragm pump for dehydration. The dewatered sludge is sent to a professional unit for treatment, and the separated water is returned to the mixed wastewater tank.
