Waste-water purification

Table 12.22 Analysis of communal influents to sewage waste-water purification plants...

The aims of this study are to investigate the removability of resorcinol and catechol from aqueous solutions by adsorption onto ACC in relation to waste water purification and to determine kinetic and equilibrium adsorption models. 

The use of perchloroethylene as a cleaning agent, the use of chemicals containing Ni, Cu and Sn for surface treatments, and the use of activated charcoal for waste water purification are preferred areas for Chemical Leasing implementation. 

Example 31 Scale-up of flotation cells for waste water purification... 

Following the biological waste water purification, an easy separation of activated sludge flocks can be achieved by flotation. To facilitate this separation, the flotation cell is subdivided into two parts, each having equal superficial areas, Fig. 58. The inner cylindrical vessel serves as the aeration chamber, this being equipped with the forementioned funnel-shaped nozzle. Here, particles are brought into intimate con-... 

Example 30 Fine grinding of solids in stirred media mills 129 Example 31 Scale-up of flotation cells for waste water purification 133 Example 32 Description of the temporal course of spin drying in centrifugal filters 140... 

This section describes the properties of [M(L)(S )J complexes in which L represents various small molecules. The NO complexes, for example, are considered important intermediates in many reactions, ranging from waste water purifications to the bacterial nitrate-ammonia or nitrate-dinitrogen conversion or the mammalian bioregulation, in which NO acts as neurotransmitter (99-104). 

Efforts are being made to reduce waste water by recycling in the milling process and to decrease its environmental pollution by treatment with biological or physical processes prior to its discharge (22). A number of alternative technologies are available for waste water purification (18-21) however, they are costly and difficult to apply. 

Tsygankov, A.A., Fedorov, A.S., Talipova, I.V., Laurinavichene, T.V., Miyake, J., Gogotov, I.N. (1998a). Application of immobilised phototrophic bacteria for waste water purification and hydrogen production. Appl. Biochem. Microbiol. 34,362-366. 

If /tpias, = constant, it is a Bingham plastic. This class of materials includes mineral slurries, highly concentrated suspensions of fine particles, meat soup extracts and the activated sludge in waste water purification. If the yield value is first exceeded at a particular shear rate, this is termed Herschel-Buckley viscosity behavior, an example being tomato soup concentrate [36]. 

For surface aeration (the system pressure p is at least in biological waste water purification atmospheric pressure) the following applies ... 

A considerable disadvantage of the sulfite method is that the liquid contains much salt, making the gas bubble coalescence not comparable with those in material systems with low salt contents (see Section 4.10). This disadvantage first attracted attention in studies of the absorption behavior in gassing devices for biological systems and for waste water purification and was the reason for looking for an alternative. This was found in the hydrazine method [624]. 

Coalescence processes are not only important in industrial chemistry and in biotechnology, but are ever more important in aerobic waste water purification, since so-called fine bubble aeration became established over surface aeration. It is therefore hardly surprising, that there has recently been strong research activity in this field [32, 570], (Bubble coalescence is not involved in surface aeration [625].)... 

Sintered glass or ceramic plates and perforated metal plates are classical gas spargers (dispersers) for bubble columns. Static mixers and nozzles became available with the emergence of biological waste water purification. They all realize gas... 

If the injectors are utilized for supplying activated sludge with aerial oxygen in a biological waste water purification plant, it is of particularly interest that they... 

Biological waste water purification (aerobic) Onken [109], Deckwer [28]... 

The system operates as a rotary drum screen with continuous washing to prevent clogging of the meshes (Fig. 3.48). Such systems are part of a technological line as a substitute for sedimentation in the case of waste-water purification they can replace flotation equipment. The efficiency of separation carried out in this way is about 60%. 

The choice of a particular drying method is also partly dictated by the scale of the operation. Where it is necessary to remove vast quantities of water from a very dilute solution, e.g. for purposes of waste water purification, freeze-drying is completely unrealistic. On the other hand, the method has been successfully used to dry valuable books and documents in libraries that have suffered flood damage. 

The principal advantages of this type of cyclic system with transient operating techniques are apparent in bioprocesses whose maximum productivity is in a transient region. The products of secondary metabolism (Pirt, 1974) are a typical example of this group of processes. Another group consists of processes whose optimal operation requires an optimal substrate concentration— biomass production with bakers yeast, for example (Aiba et al., 1976)—or where the process is subject to substrate inhibition. An important area of application for this is in biological waste water purification. These periodic modes of operation generally show increased productivity. More systematic and detailed study is needed in this area. 

Figure 5.38. Kinetics of adsorption (biosorption) in biological waste water purification. Time course of chemical and biological oxygen demand expressed as eliminated substrate and degraded substrate following the reaction scheme of substrate degradation and substrate elimination, and evaluation of the rate of adsorption from the difference in chemical and biological rates (Theophilou et al., 1978). The final level Si represents the undegradable substrate. The value of S a represents the maximal capacity of cells (sludge) to adsorb substrate (phenomenon of biosorption ).

Figure 5.55. Reaction with a mixed population of microorganisms in a low-loaded waste water purification operation as a function of the time course of environmental changes (mixed substrate, Sc.n.p)- saprophytic bacteria X2, nitrification bacteria X3, denitrifying bacteria X4 to Xi, organisms in the food chain. (Adapted from Wilderer and Hartmann, 1978.)...

Figure 5.63. The time-dependent change in the maximum rate of substrate use, s,max as an illustration of nonstationary behavior (dynamic kinetics) of a bioprocess such as this example of waste water purification (1) easily metabolizable, synthetic medium, (2) difficult to metabolize medium such as starch, (3) mixture of easily metabolized substrate and suspended particles in waste water. Tli = delay time for s,max- (Adapted from Mona et al., 1978.)...

Poly(methyl acrylate)/Fe304 Waste-water purification [257]... 

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