The Biological Process

The efficacy of the biological mercury removal process has been adequately demonstrated from a microbiological and biochemical viewpoint. The kinetics of the biological process, bioreactor design and the the effects of process parameters such as aeration rate, SRT and HRT variations on removal of 

---

Prepare the aqueous waste for biological treatment by removing excessive load or components that will inhibit the biological processes. 

The process of target identification analyzes a complex disease process by dissecting it into its fundamental components. This makes it possible to identify the one that is most integral to the manifestation of the disease. Target identification aims to understand the biological processes related to a disease, and to identify its mechanism and the structure of individual elements of the disease. Commonly these individual elements are receptors, enzymes, etc., which become the target of new drugs. 

Dinitrogen is fixed either by natural processes or by industrial ammonia (qv) production (1,8,9). The estimates for the aimual biological contribution range around 100-200 x 10 t. Industrial fixation contributes about 50 x 10 t/yr for fertilizer uses (see Fertilizers). Other processes, eg, lightning and combustion, are estimated to fix about 30 x 10 t/yr. Thus the biological process represents the majority (ca 65%) of the total aimual fixation rate, contributing about three times as much as the commercial production of fertilizer. 

Water reuse is usually a question of the tradeoff between the costs of raw water and the costs associated with treatment for reuse and for discharge. If biological treatment is to be employed, several factors must be considered. These are an increase in concentration of organics, both degradable and nondegradable. This may have a negative effect in terms of final effluent toxicity. An increase in temperature or total dissolved soHds may adversely affect the performance of the biological process. 

Virtually all the biological processes, in which vitamin Bn is active, involve substituent exchange of the type ... 

Oxidation-reduction reactions in water are dominated by the biological processes of photosynthesis and organic matter oxidation. A very different set of oxidation reactions occurs within the gas phase of the atmosphere, often a consequence of photochemical production and destruction of ozone (O3). While such reactions are of great importance to chemistry of the atmosphere - e.g., they limit the lifetime in the atmosphere of species like CO and CH4 - the global amount of these reactions is trivial compared to the global O2 production and consumption by photosynthesis and respiration. 

The epidemiological evidence suggests that diet is a significant factor in the development of cancer. In their classic epidemiological study, Doll and Peto (1981) estimated that diet was responsible for as many as 35% of cancers in the West. An encyclopaedic report on nutrition and cancer by the World Cancer Research Fund (1997) has confirmed the central importance of diet as a major determinant of many forms of cancer across the globe. The interactions between diet and the biological processes leading to the... 

One common application of liquid-liquid extraction is the removal and recovery of phenol and compounds of phenol from wastewaters. Although phenol can be removed by biological treatment, only limited levels can be treated biologically. Variations in phenol concentration are also a problem with biological treatment, since the biological processes take time to adjust to the variations. 

Silicones are ecologically inert, having no effect on aerobic or anaerobic bacteria. Thus they do not inhibit the biological processes taking place during waste water treatment. 

SCHEME 1 Schematic illustration of the biological process of 02 dismutation into 02 and H202 catalyzed by Cu, Zn-SOD via a cyclic oxidation-reduction electron transfer mechanism. (Reprinted from [98], with permission from Elsevier.)... 

The biological processes in biofilms are either described by 1-order or 0-order kinetics. However, the 0-order reaction is of specific importance for sewer biofilms as is also the case for treatment processes of wastewater in biofilters. The saturation constant, Ks, is normally insignificant compared with the substrate concentration, and the biofilm kinetics [cf. Equation (2.20)], is therefore 0-order. As shown in Figure 2.8, two different conditions exist the biofilm is either fully penetrated or partly penetrated, corresponding to either a fully effective or a partly effective biofilm. The distinction between these two situations can be expressed by means of a dimensionless constant, P, called the penetration ratio (Harremoes, 1978). For each of these two situations, the flux of substrate across the biofilm surface can neglect the stagnant liquid film being calculated [Equations (2.23) and (2.25)] ... 

A number of chemicals have been used to control sulfide. The following are the most commonly used with different effects on the biological processes. 

The flow rate and concentration of wastewater do not remain constant but vary during the course of the day and are also dependent on the time of year. If the flow rate is too high, loss of micro-organisms by washout may occur in secondary treatment processes. If the flow rate is too low, then the lack of nutrients will lead to a reduction of the micro-organism population. Wastewaters entering a treatment plant usually flow first into an equalisation basin, so that the flow rate out of the basin is maintained constant, or between prescribed limits, to protect the subsequent processes. The equalisation tank also reduces the effect of toxic shocks on the biological processes within the main treatment plant. 

---