CS269561B1 - Waste water treatment or purification method - Google Patents

Abstract

It takes place in the coarse pre-treatment facility and/or in the pumping sump and/or in a selected part of the sewage treatment plant, by processing the sludge pre-treated by aeration, supplied from the treatment facility. Its essence lies in the fact that the wastewater is treated with short-term aerated raw sludge taken from the primary sedimentation tank, or with a short-term aerated mixture of this raw sludge and activated sludge taken from the biological stage of the treatment facility. The method uses bacterial revitalization of short-term aerated raw sludge or its mixture with activated sludge, which, even with a short-term supply of air, allows for reaction changes in the aerobic and facultative aerobic range. As a result of these processes, the ability to break down high-molecular substances increases, sorption forces and other physical, chemical and biological processes develop. It allows to intensify overstretched water treatment plants with lower investment costs, or to directly treat wastewater where complete treatment is not required. It is suitable for municipal wastewater and for industrial wastewater containing easily degradable organic compounds, such as wastewater from the food industry.

Description

The invention relates to a process for the purification or pre-purification of wastewater and industrial wastewater containing more easily degradable substances in coarse pre-purification facilities and/or in a pumping station and/or in a selected part of a sewer system.

Currently, several methods of treating or pretreating wastewater in a sewage treatment plant or in facilities for rough pretreatment are known. They are based either on the construction of an aeration reactor in a sewage treatment plant (e.g. USSR patent 491,351, Czechoslovakia patent 186,414), or they use the injection of oxygen or oxygen-rich gas into the wastewater in a sewage treatment plant (US patent 4,148,726), or alternatively into a sewage treatment plant, which requires pumping water from the treatment plant, its aeration and boiling it back into the sewage treatment plant (US patent 4,196,074). The aforementioned methods are investment-intensive and, above all, energy-intensive.

In the ČSSR a.o.č. 240.534 a method of pre-treatment or pre-treatment of wastewater in a sewage treatment plant is described, in which the wastewater is treated with pre-treated activated sludge in an aerobic state. Excess activated sludge from the treatment facility is used. The disadvantage is the relatively small amount of available excess activated sludge.

The disadvantage of the described procedures is largely eliminated by the method of cleaning or pre-cleaning wastewater in rough pre-cleaning facilities and/or in a pumping sump and/or in a selected part of the sewer 181010, according to the invention.

The essence of the invention lies in the fact that the wastewater is treated with raw sludge taken from the primary sedimentation and aerated for 1 to 3 minutes or with a mixture of this raw sludge and activated sludge taken from the biological stage of the treatment facility, aerated for 1 to 30 minutes. The mutual ratio of the activated and raw sludge in the mixture is 0.01 to 40: 99.99 to 60 parts by weight.

In the process according to the invention, bacterially activated short-term aerated raw coal is used and its capacity for activated sludge is increased, which even with short-term air supply allows for reactive changes in the aerobic and facultative anaerobic regions. As a result of these changes, the ability to absorb high-molecular substances increases, sorption processes and other physical, chemical and biological processes develop.

Aeration is carried out in a suitable aeration device.

The method of wastewater treatment or pre-treatment uses the volume of a selected part of the sewer system, the pumping sump, mechanical pre-treatment facilities and a partial settling tank as reaction spaces. This allows for the intensification of existing treatment plants with lower investment costs and the treatment of wastewater where complete treatment is not considered.

The method of purification or pre-purification of wastewater according to the invention is illustrated by the technological scheme shown in the attached drawing and the attached examples. Fig. 1 shows purification using the spaces of the pumping sump 1, mechanical pre-purification objects 2 and the settling tank 3. Raw sludge from the settling tank 3, pre-treated by short-term aeration in the aeration device 6, is fed into these spaces through the pipe 5 and the pump 4. Clean wastewater flows into the settling tank 3, where sludge is separated from it by sedimentation, which is returned to the purification (pre-purification) process. If necessary, the pre-treated water is further purified by flowing into the biological reactor 7 and the settling tank 8. The separated excess sludge from this stage of purification flows through the pipe 9 into the aeration device 6 and together with the raw sludge from the settling tank 3 into the pumping sump 1. The excess sludge from the process leaves the system through the pipe 10. The sludge can be advantageously brought through the pipe 12 to the selected sewer outlet 11 and thus use the natural biologically active parts of the surface of the sewage sewer and the contact time of the sludge and wastewater. In the case of sufficient contact time of the wastewater and sludge, it is possible to bring the sludge directly into the premises of the mechanical pre-treatment facilities 2 through the pipe 13.

Example 1

In municipal wastewater, which also contains wastewater from a septic tank characterized by 215 and 387 mg.l ^-1 BOD _& 320 and 585 mg.l ^-1 COD, aa was introduced into the selected part of the sewer before the culvert, aerated sludge from primary sedimentation for 17 to 22 minutes.

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The contact time of the wastewater:alkali. was > 18 to 25 seconds. The purification efficiency < according to the invention was on average 75% for BOD_; 77% for COD and 75% for suspended solids.

Example 2

Municipal wastewater characterized at the inflow by 145 to 162 mg/l BOD, 290 to 339 mg/l COD was fed into the pumping station in front of the treatment plant with sludge from the primary sedimentation and excess sludge from the aerobic reactor, aerated for 12 to 18 minutes.

The contact time of the wastewater and sludge was 12 to 21 seconds. The purification efficiency according to the invention showed an average of 66.8% for BOD, 67.0% for COD and 78.0 for suspended solids.

Example 3

Poultry processing wastewater characterized at the inflow by 600 - 900 mg.l~^ BOD ₅ , 1000 - 1700 mg.l! COD aa was fed into the pumping sump before the sludge from the sedimentation tank was aerated for at least 20 minutes.

The contact time was 10 to 20 minutes. The purification efficiency according to the invention showed an average of 69.0% according to BSKg, 62% according to COD and 60% according to NL.

Claims (1)

SUBJECT OF THE INVENTION Method of cleaning or pre-treating municipal wastewater and intermediate waste water containing more easily degradable organic substances in rough pre-treatment facilities and/or in a pumping pit and/or in a selected part of the sewer system, characterized in that the wastewater is treated with raw sludge taken from the primary treatment plant, aerated for 1 to 30 minutes, or with a mixture of this raw sludge and activated sludge taken from the biological stage of the treatment plant, aerated for 1 to 30 minutes, wherein the mutual ratio of active and activated sludge in the mixture is 0.01 to 40 parts by weight and 99.99 to 60 parts by weight.