Sewage Technology
© H.-G. Oed
Avoidance of waste water takes priority over treatment. Minimization of fresh water consumption, recycling, and repeated usage of process water, as well as the use of less problematic chemicals and changes in processes, are considered to be the most effective measures for reducing both the amount and the impact of waste water generated by households and commercial and industrial operations.
In Germany, the use of waste water treatment plants for the purification of municipal and industrial waste water is widespread. To a great extent, hazardous and undesirable materials are removed. This ensures that the watercourses, into which the treated waste water is discharged, retain good water quality.
Conventional waste water treatment methods are divided into
• mechanical,
• chemical, and
• biological processes.
They are often combined with each other, or often also supplemented with chemical/physical treatment methods.
Increasing significance is now placed on membrane filtration systems, since only they allow the removal of wastewater germs that are critical for human health, such viruses, bacteria, and parasites. The classical waste water treatment methods do not match this hygienic requirement.
A sewage-free fish farm
A combination of different membrane technologies is used to treat the circulation water in a new fish farm. The facility produces no wastewater and is energy-efficient.
Advanced biological purification of industrial wastewaters for the minimisation of residual COD (part 2)
The exemplary operation of the sequencing-batch-reactor process developed on a semi-industrial scale has been demonstrated using wastewaters from the paper and cellulose industry. Positive results obtained from earlier laboratory investigations have been confirmed, and the practical capability of this process for the minimisation of the sewage load in the Elbe has been demonstrated.
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Advanced biological purification of industrial wastewaters for the minimisation of residual COD: part 1
Using industrial wastewaters from the Czech paper industry, exemplary laboratory analyses have been conducted in biological wastewater treatment installations with a view to achieving the maximum possible reduction of chemically degradable substances. Periodic Sequencing Batch Reactor (SBR) technology has proved to be particularly suitable for this purpose.
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In a paper factory up to 100% waste paper is used for the production of newsprint. The biological waste water treatment plant is extended with a third stage (flotation) in order to reduce the chemical oxygen demand (COD) in the wash water. A goal is to obtain industrial water quality. For the thermal utilization of the residual substances from fiber production and waste water treatment the waste water treatment unit is supplemented by a sludge treatment and drainage facility.
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In comparison with completely stirred installations, the plug flow process has reduced chemical oxygen demand (COD) by 10 – 15%. The treatment of older sludge has resulted in more extensive COD elimination. For denitrification and biological phosphate elimination, this process has also shown clear advantages over conventional practices.
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Advanced oxidation processes in drinking water treatment for elimination of disinfectants and the reduction of potential for reinfection: comparison of oxidation processes
Ozonisation, peroxone, ozone/UV and hydrogen peroxide treatment processes have been applied to three representative waters for the purposes of drinking water treatment. Results obtained for the degradation of trace materials, the formation of disinfection by-products and the tendency towards reinfection have been compared and documented in a comprehensive tabular compilation.
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Advanced oxidation processes in drinking water treatment for the elimination of disinfectants and the reduction of potential for reinfection: analysis of potential applications for the combined hydrogen peroxide/ozone oxidation process
In laboratory and semi-industrial tests, the combined oxidation method has proved to be a fundamentally suitable pre-treatment process. Particular strengths have been observed in the removal of impurities from water containing mineral oil hydrocarbons. In consequence, this method is primarily suitable as a standby process for potential surges in the pollution load.
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Advanced purification of municipal sewage: AOX removal using powdered carbon, microfiltration for the removal of bacteria and phosphorous and catalytic denitrification
The effective elimination of bacteria and phosphorous has been achieved using a process combination of precipitation/flocculation/microscreening-microfiltration. Conversely, the use of powdered carbon has not produced any significant removal of adsorbable organic halogen compounds (AOX). Catalytic denitrification has also failed to achieve the desired success.
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Advanced textile waste water purification by means of flocculation, filtration and adsorption in the local clarification plant Albstadt-Ebingen
The waste water loaded heavily by the waste water from the Textilfaerbereien is biologically cleaned and subsequently treated by means of a combined application of activated carbon adsorption, chemical precipitation/flocculation and filtration (AFF procedure). The visible color could be eliminated, the biologically nondegradable, organic substances including the organic halogen compounds and the phosphorus could be substantially reduced.
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Advanced waste water purification by alternating denitrification with fixed bed reactors
By the parallel operation of a submersed and a fixed bed plant according to the alternating denitrification procedure the transferability of this N-elimination procedure to the fixed bed technology was examined. Also, the suspensa elimination performance as well as the observance of effluent values for filterable materials were compared in both procedures. The procedure of the alternating denitrification could be installed with satisfying results on the fixed bed plant. The ammonium degradation was heavily affected by the suitable procedure, in particular the correct combination of inlet quantities and duration of phase times (detailed information in German).
