DE10316380A1 - Process to co-treat effluent water and water-based filtrate by progressive change in the ratio of the two in a sequential batch reduction reactor - Google Patents

Abstract

In a waste water treatment process, filtrate effluent water is co-treated within a given cycle in a sequential batch reduction (SBR) process. During the (essentially only the first) filling phase, water effluent and supplementary filtrate water are introduced to the SBR reactor. The effluent water may be selected as tending to zero content. During the (essentially last) filling phase, essentially only effluent water (and little filtrate) is introduced to the reactor. The sludge excess containing nitric/nitrate bacteria and bio-phosphate bacteria is surrendered to conventional biological treatment. From 10-50% of the total effluent water is co-treated with filtrate water in an SBR reactor, while the remainder of the effluent water is treated in a conventional biological process. The relative proportion of effluent water and filtrate water to be combined and treated is determined by NH4-N and/or NO3-N sensors.

Description

The The invention relates to a method for wastewater treatment with cycle-specific Filtratabwassermitbehandlung. A filtrate wastewater treatment in an SBR partial flow treatment plant, i.e. a plant that Wastewater is cleaned discontinuously (see previous patent applications 196 40 762 and 198 02 957 of the applicant) is usually used with impoundment activation systems causes, in contrast to plants with classic activation processes no over have a separate clarifier, but the biological cleaning phases through aeration / mixing and sedimentation drain one after the other in a pool.

By improved measurement and control techniques has increased performance of the impoundment revitalization process significantly improved so that it because of cheaper Construction costs are becoming more and more attractive.

task the invention is the operational management of the shocking in such a way to improve that more nitificants are accumulated in the sludge and stable, low sludge indices are made possible.

In particular by intermittent Charging the SBR reactors with the features of the main claim this will be solved. The subclaims give advantageous designs of the procedure again.

On Another advantage of the new process is an improvement in Wastewater treatment, d. H. of nutrient elimination (which is essentially denitrification and biological P-elimination goes, while minimizing the operating costs).

there becomes the management the cycle strategies in the DIC-SBR process or other SBR processes with at least 2 internal cycles or with at least two separate ones Befüllphasen in the course of an overall cycle in such a way that despite the treatment of highly contaminated filtrate wastewater from sludge digestion or another separate partial wastewater stream with high nitrogen concentrations (all these wastewater are referred to as filtrate wastewater) not too elevated Nitrogen drainage values are coming.

• • Die Nitratbildung nach Abschluss der ersten internen Belüftungsphase auf einen (für jeden Zyklus automatisch neu zu ermittelnden) Maximalwert zu setzen (und begrenzen), so dass nach der nachfolgenden zweiten Beschickung ohne Filtratabwasser eine Mindestmenge an Nitrat denitrifiziert wird, damit nach der zweiten internen Belüftungsphase der N_ges,anorg Überwachungswert oder ein selbst gewählter N_ges,anorg Ablaufwert nicht überschritten wird.
• • Der Nitrat-N-Gehalt am Beginn der ersten Beschickungsphase unterhalb einer Grenzschwelle von ca. 6 mg/l liegt, die die biologische P-Elimination beeinträchtigt,
• • Dadurch bedingt: Der Anteil an Nitrifikanten und Bio-P-aktiven Bakterien in diesen SBR-Überschußschlämmen maximiert wird, damit in einer gegebenenfalls parallel zur SBR-Anlage vorhandene konventionelle Belebtschlammbiologie, in die die SBR-Überschußschlämme geleitet werden, die oxischen Phasen bzw. Volumina bedarfgerecht reduziert werden können zwecks Verbesserung der Denitrifikation und biologischen Phosphor Elimination.

According to the invention, the object is achieved by simultaneously carrying out a maximum possible supply of filtrate water as part of the first internal feeds in such a way that

• • After the first internal aeration phase, the nitrate formation must be set (and limited) to a maximum value (to be automatically determined for each cycle) so that after the subsequent second feed without filtrate waste water, a minimum amount of nitrate is denitrified, so that after the second internal aeration phase the N _{tot, anorg} monitoring _value or a self-selected N _{tot, anorg expiry value is} not exceeded.
• • The nitrate N content at the beginning of the first loading phase is below a threshold of approx. 6 mg / l, which affects the biological P elimination,
• • As a result: The proportion of nitrificants and bio-P-active bacteria in these SBR excess sludges is maximized, so that the oxic phases or, respectively, in a conventional activated sludge biology, possibly parallel to the SBR plant, into which the SBR excess sludges are led, Volumes can be reduced as needed to improve denitrification and biological phosphorus elimination.

Generally better utilization of the reaction volumes is possible and this effect can occur in new sewage treatment plants if necessary for a saving in operating costs or construction costs (savings of design reserves).

For the proposed regulation / control, online measurements are required in the reactors for the continuous determination of the current NH ₄ -N and NO ₃ -N concentrations. On the basis of the known, directly or indirectly measured concentrations of these two substances in the "normal" inlet wastewater and in the filtrate wastewater, the maximum feed quantity is determined and the resulting concentrations are monitored with the online measurements. An indirect determination consists, for example, in that the previous cycle can be automatically calculated back to the current concentrations in both the filtrate and the feed waste water.

This ensures that after the end of the first aeration phase, ie the first nitrification phase (and thus after reducing the NH ₄ -N concentration to, for example, a maximum of 1 mg / l), the NO ₃ -N value does not have a value of, for example, 15 mg / l exceeds.

The subsequent second feed without filtrate waste water (and thus a significantly lower nitrogen concentration) is then carried out in such a quantity that within a maximum of Available phase without aeration Denitrification rates (ie the microbiological conversion of NO ₃ to N ₂ ) can be realized, which lead to a reduction of the nitrate concentrations to eg below 4 mg / l. At the same time, this controlled operation ensures that the NH ₄ -N concentration does not exceed a selected limit value of 5 mg / l, for example, during this second loading. This ultimately ensures that after the subsequent second and last aeration phase the total nitrogen concentration is <5 + 4 = 9 mg / l.

In order to ensures that the total nitrogen concentration in the clear water drain is always below this value and at the beginning of the first loading phase the nitrate concentration does not exceed 6 mg / l, since a corresponding proportion during the Sedimentation phase of the activated sludge has been denitrified.

Based several detailed studies as well as based on the results many on an industrial scale operated systems are the nitri and denitrification rates of SBR plants, especially those with an upstream buffer tank, exceptionally small fluctuations subjected. The regulated operational management explained in the above paragraph, the is based on the nitri and denitrification rates of the previous ones Cycles, lets can therefore be realized with a very high degree of forecasting certainty.

Therefore essentially the advantage is realized that a considerable Volume saving for both the SBR reactors due to the exact control of the filtrate water metering in the reactors will, as well conventional biology due to constant vaccination achieved with high concentrations of nitrificants and Bio-P bacteria becomes. There are also other advantages in terms of what is required Fällmittelbedarfes for the supportive P elimination as well as regarding a very extensive N and P elimination.

The permanent Feed excess SBR sludge into one Experience has shown that conventional biology also affects the sludge index there Cheap because this, at least for SBR systems with batch feed is generally significantly lower than that of comparable conventional ones Investments.

Claims (4)

Process for wastewater treatment with cycle-specific filtrate wastewater treatment in an SBR plant, characterized in that wastewater and additional filtrate water are introduced into the reactors of the SBR plant during the filling phases only in the context of the essentially first feeds), the wastewater fraction being selectable to zero , and during the filling phases in the course of the essentially last feed essentially only feed waste water is passed into the reactors. A method according to claim 1, characterized in that the excess sludge as excess sludge enriched with nitrificants and Bio-P bacteria is introduced into a conventional biology. Method according to one of the preceding claims, characterized characterized that 10-50% of the total amount of wastewater treated with the filtrate waste water in an SBR biology and the remaining Wastewater is treated in a conventional biology. Method according to one of the preceding claims, characterized by NH ₄ -N and / or NO ₃ -N sensors for determining the amount of the wastewater and filtrate water to be added in each case to effect the desired and controlled N-elimination in the reactors.