Biological waste water treatment

The collected excess sludges of the different sedimentations are mechanically dewatered to about 35 - 50 % dry substance and incinerated by fluidised bed combustion. The press water is also collected and combined with the sewage from the plant. 

Excitation of the pH-vaiue, zinc reduction, removing severai buiky materiais 

Waste water treatment with micro-organisms 

Separating the sludge including the micro-organisms from the cleaned water 

The treatment of the sewage sludge has to be taken into account. Operational data 

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LINPOR [Linde porous medium] A biological waste water treatment process, using an open-pore plastic foam for retaining the biomass. Its use enables the capacity of an activated sludge plant to be increased without adding extra tanks. Invented at the Technische Universitat, Munich, and further developed by Linde, Munich. See also CAPTOR. 

APEOs and their acidic and neutral metabolites can be halogenated to produce chlorinated and brominated products. The formation of these compounds has been reported during the chlorination processes at drinking water treatment plants [1,35,36] and after biological waste-water treatment [37]. 

Cresols may be disposed of by landfill, land applications, biological waste water treatment, or incineration. In an activated sludge system, cresols exhibit a 96% reduction of the chemical oxygen demand and a biodegradation rate of 55 mg of oxygen/g-hour. Cresols may be disposed of in a rotary kiln incinerator with a temperature range of 820-C-1600-C and a residence time of seconds. Cresols may also be disposed of in a fluidized bed incinerator with a temperature range of 450 C-980 C and a residence time of seconds (HSDB 1989). 

Figure 2.16 One example of a group of widely used chemicals that, as a consequence of biological waste-water treatment, are converted into persistent objectionable degradation intermediates.

Horan, N. Biological Waste Water Treatment Systems, 2nd Edition, John Wiley Sons, Inc., New York. NY, 2001. 

Meakins, N.C., Bubb, J.M., Lester, J.N. (1994) The behaviour of the. v-triazinc herbicides, atrazine and simazine, during primary and secondary biological waste water treatment. Chemosphere 28, 1611-1622. 

Gas/liquid contacting is frequently encountered in chemical reaction and bioprocess engineering. For reactions in gas/liquid systems (oxidation, hydrogenation, chlorination, and so on) and aerobic fermentation processes (including biological waste water treatment), the gaseous reaction partner must first be dissolved in the liquid. In order to increase its absorption rate, the gas must be dispersed into fine bubbles in the liquid. A fast rotating stirrer (e.g. a turbine stirrer), to which the gas is supplied from below, is normally used for this purpose (see the sketch in Fig. 34). 

Biological Conversion and Degradation 3.1 Biological Waste Water Treatment... 

A comparison between the performance of conventional biological waste-water treatment basins and the reciprocating bioreactor is given in Table XXVI. As shown, the conversion rate in the reciprocating reactor can be as high as more than four times that obtained in a conventional bioreactor. 

The surface aerator has been used for decades in biological waste-water treatment with H < 4 m. For various sizes of turbine stirrers whose disks were positioned exactly in the surface of the liquid, the mass-transfer coefficient can also be related as... 

For best performance aerobic biological waste water treatment plants must be maintained at a constant dissolved oxygen (DO) level. Under certain conditions, e.g. adverse weather conditions or under biological oxygen demand (BOD) overloaded conditions, DO levels drop and treatment effectiveness can be seriously reduced. Continuous running under lower than optimum DO levels leads to biological upsets such as proliferation of anaerobic or filimentous... 

Waste water, containing a variety of colloids, is often treated by polymeric flocculants such as polyacrylamides to precipitate the colloidal material and make it better filterable. Quite often these flocculants are high-molecular-weight weakly charged polyelectrolytes. Bacterial suspensions resulting from biological waste water treatment must also be flocculated before they can be properly separated from the purified effluent by sedimentation or filtration. 

In the course of the advent of biological waste water treatment, civil engineers have developed very different types of surface aerators (see [628] and surface aeration, Section 4.12.2). 

Glass-lined equipment is necessary with respect to the corrosiveness of the chemicals used. Approximately 7.5 tons of chemicals (without solvents) are used to produce 1 ton of 7-ACA. Because of the low biodegradability and bacterial toxicity of the chemicals used, biological waste water treatment is prohibited and the aqueous phase has to be incinerated. The organic phase (chlorinated hydrocarbons) has to be distilled and recycled. Distillation residues are incinerated too. In total about 31 tons of residues per ton of 7-ACA have to be incinerated. 

Biological waste water treatment (no toxic chemicals)... 

Biological waste water treatment has been intensified by application of special microbe preparations with a capacity for higher degradability. A polyfunctional population compiled from different bacterium strains, a mixture containing a wide metabolic spectrum mainly of fat-degrading organisms, has been prepared. By application of 1 - 2 % inoculum, the efficiency of waste water treatment could be raised from 40 - 60 % to 95 - 97 %. 

Beck, M.B., 1986. Identification, estimation and control of biological waste-water treatment processes. lEE Proceeding 133, p.254-264... 

Foam flotation during biological waste water treatments is not considered, because of the undefined properties of these systems. Aqueous media have unknown and often changing compositions and the mixed cultures consist of uninvestigated and only partly identified organisms, respectively. 

Neopentyl glycol and isobutanol are separated by distillation. Some of the recovered isobutanol is used to extract the aqueous phase formed in the aldol condensation, and the remainder is used to produce synthesis gas. The isobutanol extract contains hydroxypivalaldehyde and starting materials. It is therefore recycled to the aldol condensation reactor. The isobutanol transferred into reactor 1 then enters reactor 2 via the organic phase. This leads to an increase in the amount of isohutanol so that, after separation by distillation, some of the isobutanol can be used to produce synthesis gas. Wastewater from the bottom of the extraction column is fractionated. The low-boiling compounds formed as overhead products are also used to produce synthesis gas (Fig. 25). Wastewater from the fractionating column is treated in the biological waste-water treatment plant. 

The treatment of amine-containing scrubbing solutions requires a nitrification/denitrification stage. These treatment steps can also be carried out in an external biological waste water treatment plant. An alternative to discharge is the recovery of the amines. 

Phenols and cyanides can be biologically degraded or removed by physical-chemical treatment. Normally they are present in such low concentrations that there is no need for targeted pretreatment. Combined treatment in a sufficiently large biological waste water treatment plant is sufficient. 

If the amine is not recycled, the scrubbing concentrates can be treated in a biological waste water treatment plant with nitrogen elimination. 

The stripped water can be sent to a biological waste-water treatment plant for further processing. The gases require further treatment, such as ammonia recovery, sulfur removal recovery, or incineration/combustion. 

Table 1.2. Process engineering comparison between simple fermentation and complex fermentation bioprocess (e.g., biological waste water treatment).

The various types of plug flow bioreactors were recently surveyed by Moser (1985a). They utilize surface aeration by means of a variety of rotating brushes, rotors, cone aerators, or gas or fluid jets such as are found in biological waste water treatment plants. Beyond all mechanically driven systems, reactors can also be both aerated and mixed pneumatically, or one pump can serve for both mixing and hydrodynamic stirring. 

This method is known as the Walker plot method (Walker and Schmidt, 1944), and it is often used in the area of biological waste water treatment (Wilderer, 1976). The Walker plot has the advantage that, for various types of kinetic models (power law equations with different reaction orders as well... 

For the case of low substrate concentration, such as in biological waste water treatment, one can ultilize a formal first-order equation. From Equ. 4.29... 

In addition to the laws of enzyme microkinetics, the kinetic equations from chemical reactions based on the type 1 situation shown in Fig. 4.12 also provide a suitable approach. The power law equations with various reaction orders, n, differ in the cjt relationship of their reaction components. In Fig. 5.15, the time course of substrate concentration is compared for n = 0,1/2,1, and 2 and for Michaelis-Menten enzyme kinetics. The substrate disappearance and the oxygen utilization in biological waste water treatment may be cited as realistic examples. For the simple case, integration is possible (Levenspiel, 1972). The integrated solutions for various reaction orders are... 

Obviously, this model is of practical interest in case of biological waste water treatment (see Sect. 5.9), because it accounts for the transition between limiting and nonlimiting conditions. In these situations, Monod-type kinetics are not applicable to conserved substrates, because ju is controlled by the amount of intracellular substrate, which may deviate significantly from extracellular concentration. 

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