DEVICE FOR THE BIOLOGICAL PURIFICATION OF WASTE WATER.

Description

YES one CONSULENZA B!UVÌi,i ih'1.MILAN-Piezza Castollo, j 1.167 / 78A. Description of the invention having the title: j ! "Device for the biological purification of aoq.ua! of waste" idea of ​​the company LINDE AKTIENGESELLSCHAFT I based in Wiesbaden (Germany) filed on : 2 ? (jfjfjr É9170A / 7C The invention relates to a device for the biological purification of waste water in a two-stage purification plant with oxygen supply, in which essentially organic pollutants are degegged in the first stage and essentially oxidized in the second stage | te inorganic nitrogenous compounds. With such a device, waste water is removed; I ne first mixed in the first stage with mud! | activated, with simultaneous supply of oxygen· j i For the activity of aerobic microorganisms, contenu! in the activated sludge, the organic pollutants of the waste water are partly transformed into bacterial substance and partly react with oxygen to form CO2 and water, so |chà in the first stage are oxidized in large mi | sura carbon compounds In the second stage, i after the transfer of the water mixture of rj.i ··♦·• e MMI ··» » · and and and . ·*· Mmi ***** ···*Ί · • · · * • · * ·* ** ·* • · ** ·* * ·····* · ·* * COHSIMILAN STUDY ({LENZA PATENTS WUMÀNN Pia Castello, 2 - 2 waste and activated sludge from the first stage, with a sufficient supply of oxygen, a sufficient temperature of the water and a low load of the sludge, a nitriflection of the waste water then takes place, with which, by means of the autotrophic bacteria present in the sludge, ammonium nitrogen is oxidized to nitrite and nitrate. It is known that the procedure can be implemented in two activation basins, drippers or similar devices, inserted in a box, and that a clarification basin can be inserted downstream of each of the two stages, j From which the sedimented sludge is returned to the respective stage (cf. Lehr- und Handbuoh der Abwassertechnik, vol. XI, second edition, pp.454-457). Generally, in order to guarantee the supply of oxygen in sufficient measure for the feeding of the microorganisms, it is customary to supply pure oxygen to both stages. | The drawback of this device consists in the fact that in the second stage it is possible to establish a pH of such a low value as to hinder a biological oxidation of the nitrogen. The low values ​​of the pH are due to the fact that both the oxidation of the nitrogen and the solution of carbon dioxide in water is accompanied by the formation of ions ·* · *e e IMM ·** Μ··« ♦ * ·* *1. * • · • e e e e * · * * ·• thirst ·.. · • · • » e • » e ee MM e e » e* ee e · • t · MI» • I *tee · e · · * e · · e « M• « ·*··• · · »IM - 3 - studio coHSULraf Botili imm MILAN -Piazza Castello, 2 hydrogen. The extent of the lowering of the pH is related to the initial alkalinity of the waste water, to the concentration of organic pollutants and nitrogenous compounds, as well as to the degree of oxygen utilization. One could indeed raise the pH by adding alcohols, but this measure, in addition to making waste water purification more costly, would also lead to a salification of the waste water. the invention therefore poses the problem of developing a device of the kind described at the beginning for the biological purification of the waste water in a two-stage clarification plant, which without a considerable expenditure of technical resources makes it possible to safely nitrify the aoqua say refusal. According to the invention, said problem is solved in such a way that oxygen or a high oxygen content gas is introduced into the second stage and an oxygen rich exhaust gas stream is withdrawn from the second stage and fed into the first stage, where the exhaust gas stream subtracted from the second stage is scaled to fully or at least pre-open ·· * * "····*... * ···· • · ·. * • · · and!· • ​​MIe MM • ·· and • *• « ·• · · · « and · *! »•••ee e e .. e e * · • e tee · · · * **e * » e ***** e « MM * ♦· • II» e e - 4 JAUMAHMMlLANO PATENTS CONSULTING MAT-Piai'za Castello, 2 i valently the oxygen requirement of the first;stage i With the oxidation of the carbon compounds in the first stage, only a portion of the carbonic anhydride formed is removed along with the offgases. The other part dissolves in the waste water and together with this is transferred to the second stage. Due to the introduction of oxygen or a gas with a high oxygen content in the second stage, this portion of C02 dissolved in the waste water is then absorbed by the water with the consequence of producing a relative increase in the pH of the waste water in this stage . In particular, if the drawn exhaust gas stream is proportioned so as to cover the lar By reducing or completely reducing the oxygen requirement of the first stage, the maximum possible amount of COg is then absorbed. With the consequent increase in the pH of the waste water, the nitriflection can take place without difficulty. THE As we have seen, suitable pH values ​​for nitrification can be achieved, if. i ; according to a further concept of the invention, from second stage all the exhaust gas stream is taken, which contains more than 70jé of oxygen ,*·* ··..·*eee e e *e · e·*e ee ee • eee ee · · • · ·· • e e e • eee # e mi • · ·»··* • e · i* • eee e e e e e e ·*:· ···· • I · e * *· e è • e · e e e · * e e e e · · · ·.· • e* e e · e · *··· .· * • * · • · e e ·*·4• eee* • tee - 5 - STUDIO CONSUL rn BliEVan MUÀHHMlLANO-Fiiazza Castello, 2 and less than 10# of carbon dioxide. The device according to the invention is explained in greater detail, taking into consideration a schematic representation: | In a two-stage clarification plant, a stream of waste water to be purified is first of all fed via a water supply line (5) to a first activation basin (1) in which, with the consumption of oxygen, the organic pollutants are essentially transformed into bacterial substance and are partially reacted to form CO2 and water Subsequently through a clarification basin (3)» from which the separated sludge is recirculated to the first activation basin (1)» the water stream of waste is sent to a second activation unit (2)" in which, also with oxygen consumption", the inorganic nitrogenous compounds are essentially oxidized. To cover the oxygen requirement in the two activation basins, oxygen or a gas with a high oxygen content is first fed via a gas supply line (7) to the second activation basin (2), from which it is then withdrawn e*·· *·· e ·*eee e · ·** -• e e · e e ·*· **· Ϊ* eeee e • they • e e e e:· eeee · *··* • e e • e • e·· • • ••ss *. · • e • 9··' • e ·eeee :> • *• e · • e • tea ···* • · ·eeee I - 6 - COWJLfWA PATENTS STUDY «M.V.VTNMILANO Piazza Castdio, 2 rich in oxygen, which is sent to the first activation basin (1) . There this gas is consumedt except for an exhaust gas stream, which is withdrawn from the first catch basin ( 1 ) via a gas exhaust pipe (9)ￂﾷ The purified waste water is removed from the second basin activation process (2) through a water supply pipeline (6), possibly making it pass through a re-clarification basin (4), inserted downstream of the second activation basin (2) and from which the separated mud can come recirculated in the second basin of, ! activation (2). A numerical example will serve to illustrate the device according to the invention more clearly. The first activation stage (1) is fed with a stream of water with 1000 kg / h BSB5 (biochemical oxygen requirement) and 53 kg / h. NH4-N (ammj>nic nitrogen) and with a pH of 7.5. The water stream a]) releases the activation medium (1) with a rate of 50 kg / h BSB5 and 53 kg / h NH4-N and with a pH of 6.8. The entrained sludge is separated in an intermediate ohd|griffination (3) and recirculated in the activation baoin (1). In the activation basin (1) 1140 kg / h of oxygen are consumed. After the lt ·. » * · · • * · · ... e • «tee • •••ett · · · !* MM» e e* *# · * #** e • e • 9 ## · • IMM M * • ♦ esse e te • e MI* i • *I · · • e · e • · e • · • * ♦• · · · • a* • * · * ···*a a ·a a a a

Claims

1. - 7 - STUDIO COOLCNZA PATENTS JAUMAHHMILANO-Piazz v Castello, 2 intermediate clarification (3) » the waste water stream is still treated in the second activation basin (2) and leaves this, after a final clarification carried out in the clarification basin (4) with sludge recycling, with a load of 30 kg / h BSB5 and 0.5 kg / h NH4-N and with a pH of 6.

5. In particular, an hourly quantity of 99% oxygen is fed to the second activation basin (2), which in normal conditions occupies a volume of 1040 w}. As a septic gas stream, it can be removed and fed to the first basin.activation stage (1) an hourly quantity of exhaust gas, which has a composition of 96# Og3# CO2 and 1# inert gas and under normal conditions occupies a volume of 890 m³. From the first activation stage (1) a stream of exhaust gas is then removed with an hourly quantity of inert gas, which under normal conditions occupies a volume of 100 m³ and still contains approximately 50# oxygen and 100g, the remainder being inert gas. Claim 1. - Device for the biological purification of waste water in a two-stage clarification plant with oxygen supply, in which in the first stage essentially 1|l substances are degraded. ... · · .·· •... * • ··· - e• • eeee • e #a * • aaa* Λ*... •I · ···* • ♦ • e·♦·· M*ll ·· * • I • •se ♦ • MI ee · e >sa* e ·eee ee ♦ ••V ♦ a * a • a * «M» aa aa • 11« a · - 8 - STUDIO CONSULTENZA IiREVEflI JÀUMÀNNMILANO-Piazza Castello.% organic pollutants and in the second stage essentially inorganic nitrogen compounds are absorbed, characterized in that oxygen or a gas with a high oxygen content is introduced into the second stage and an oxygen-rich exhaust gas stream is subtracted from the second stage and fed to the first stage, whereby the exhaust gas stream subtracted from the second stage is proportioned in such a way as to completely or at least predominantly cover the oxygen requirement of the first stage. 2.- Device according to relv. 1, characterized by the fact that a stream of exhaust gas is taken from the second stage, which contains more than 70% oxygen and less than 10% carbon dioxide. ·*·«• ···*· ...