The Cell as a Physico-chemical System

Tannery wastewater is one of the most pollution sources. It can cause environmental problems related to its high organic matter, suspended solids and chromium. Chromium (III) salts are the most widely used chemicals for tanning processes, causing the tannery wastewater to be highly pollutant with chromium. The main objective of this study is to investigate the pre-treatment of an actual Egyptian tannery wastewater using two systems; the first electrolytic system and the second physico-chemical system. The performances of electrolytic system at current of 10, 20, 30 and 40 A were discussed. Poor removal efficiencies of chemical oxygen demand (COD), total suspended solids (TSS), chromium (III), ammonia (NH4+ and sulfide (S2−) were obtained. In the second physico-chemical system, calcium hydroxide was used as a coagulant material for chromium precipitation and plain sedimentation was applied for reducing of COD, biochemical oxygen demand (BOD5) and TSS. The results demonstrate 98.8% removal of chromium, 31% removal of COD, 25.8% removal of BOD5 and 51.2% removal of TSS.

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The Kinetics of Growth

Journal of Experimental Biology ◽

10.1242/jeb.6.3.248 ◽

1929 ◽

Vol 6 (3) ◽

pp. 248-274 ◽

Cited By ~ 1

Author(s):

J. GRAY

Keyword(s):

Growth Rate ◽

Growth Curve ◽

Direct Proof ◽

Graphical Analysis ◽

Chemical System ◽

Accurate Analysis ◽

Quantitative Expression ◽

Rate Of Growth ◽

Physico Chemical ◽

External Conditions

A quantitative expression for the growth rate of living systems can only be obtained when the systems are homogeneous (or of known heterogeneity), and when the external conditions are constant. When more than one type of cell is present, or when the external conditions are varying, the known data (concerning even unorganised growth), are insufficient for the construction of a real equation defining the rate of growth in a given set of conditions existing at a particular instant of time. An equation representing the size of a population of cells or of an organism in terms of age, yields, on differentiation, a quantitative but empirical representation of the factors controlling the rate of growth, but since more than one equation can always represent a typical growth curve within the limits of probable error, a selection of one particular equation rests solely on the intrinsic probability of its differentiated form. The degree of probability can only be established by direct experiment. In the growing body of a metazoon the conditions of growth are extremely complex, and it is difficult to express the growth rate of the whole organism in terms of rational units. Graphical treatment of the data underlying a typical growth curve is liable to produce errors of considerable magnitude, and often tends to confuse the facts. The units which compose a metazoon's body form a very heterogeneous system, in which the rate of growth of one organ is dependent on that of others. It is, therefore, intrinsically improbable that the behaviour of such a system should conform to that of a simple chemical system in which the variables are few in number and capable of accurate analysis. The conception of growth as a simple physico-chemical process should not be accepted in the absence of very rigid and direct proof; at present, it rests on the results of a process of graphical analysis which is often, if not always, of a relatively inaccurate nature.

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Investigation of the properties of the brominated phthalate-containing system and determination of its application areas

Proceedings of the Voronezh State University of Engineering Technologies ◽

10.20914/2310-1202-2021-1-290-296 ◽

2021 ◽

Vol 83 (1) ◽

pp. 290-296

Author(s):

R. N. Plotnikova

Keyword(s):

Solubility Parameter ◽

Phthalic Acid ◽

Classical Model ◽

Multicomponent System ◽

Polymer Materials ◽

Chemical System ◽

Spectral Studies ◽

Physico Chemical ◽

Carbon Carbon Bonds

The structure of a multicomponent system including phthalic acid esters has been studied using the methods of infrared spectroscopy and proton magnetic resonance. The obtained spectrograms are analyzed, indicating the presence of peaks corresponding to certain radicals present in the assumed structure of the main organic compounds of the multicomponent system. The presence of bromine atoms in the radicals of the molecules that make up the phthalate-containing system is established. The structure of the molecules of the basic component of the brominated system is shown. Spectral studies have confirmed the classical model of bromine addition at the site of double carbon-carbon bonds in the phthalate radical. It is established that the brominated multicomponent physico-chemical system is represented to a greater extent by esters of o-phthalic acid. The solubility parameter of the system under study is determined by the calculation method. The solubility parameter 35.3 (kJ/m3)0.5 was experimentally confirmed for a brominated phthalate-containing system. It is shown that the Small formula used to calculate the parameters of individual substances can be used to estimate the parameters of complex multicomponent systems. Polymer materials with the minimum values of deviations in the solubility parameter with the system under study, for which ~±1.5, are determined. It is established that the system under study can be used as an effective plasticizer of polybutyl acrylate, polyisoprene, polyvinyl chloride, and polyvinyl acetate.

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A high rate clarifier for load levelling in sewerage systems

Water Science & Technology ◽

10.2166/wst.2003.0632 ◽

2003 ◽

Vol 47 (12) ◽

pp. 89-94

Author(s):

R.A. Jago ◽

A. Davey ◽

H. Li

Keyword(s):

Water Reuse ◽

Sewage Treatment ◽

Sewage Treatment Plant ◽

Treatment Plant ◽

Quality Parameters ◽

High Rate ◽

Chemical System ◽

Operational Conditions ◽

Plant Environment ◽

Physico Chemical

The combining of chemically assisted clarification with a proprietary physical separation technology has led to a high rate process for clarifying flocculated sewage and other waste streams. This hybrid physico-chemical system, known as the CDS Fine Solids Separation (FSS) System, was developed over a two year period within a sewage treatment plant environment. This paper summarises the results of a recent field trial of the system with a Victorian water authority which experiences heavy loading of sewers in a coastal town during holiday periods. The trial sought to evaluate the FSS as a tool for smoothing the load on the 11 km long sewer to the sewage treatment plant (STP). The FSS system could possibly enable the costly augmentation of the sewer to be deferred, particularly as the capacity of the existing sewer pipe is satisfactory for most of the year. Water quality parameters were determined for a range of flowrates and operational conditions over a two month period. Large reductions were achieved in TSS, TP, FC, turbidity and BOD5, with only minimal reductions in NH3 and TON. These results showed that the FSS could meet the authority's objectives for load levelling and would provide a 20-25% increase in effective sewer capacity. The data are also discussed in terms of possible use of the effluent from the FSS for water reuse applications.

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