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Particles finer than 0.1 μm (10 −7 m) in water remain continuously in motion due to electrostatic charge (often negative) which causes them to repel each other. [citation needed] Once their electrostatic charge is neutralized by the use of a coagulant chemical, the finer particles start to collide and agglomerate (collect together) under the influence of Van der Waals forces.
Finings’ actions may be broadly categorized as either electrostatic, adsorbent, ionic, or enzymatic.. The electrostatic types comprise the vast majority; including all but activated carbon, fining yeast, PVPP, copper sulfate, pectinase and pectolase.
Many substances have historically been used as fining agents, including dried blood powder. [5] There are two general types of fining agents — organic compounds and solid/mineral materials. [4] Organic compounds used as fining agents are generally animal based, a possible cause of concern to vegans. [6]
Choosing a research question is an essential element of both quantitative and qualitative research. Investigation will require data collection and analysis, and the methodology for this will vary widely. Good research questions seek to improve knowledge on an important topic, and are usually narrow and specific. [1]
Econometrics may use standard statistical models to study economic questions, but most often they are with observational data, rather than in controlled experiments. [10] In this, the design of observational studies in econometrics is similar to the design of studies in other observational disciplines, such as astronomy, epidemiology, sociology and political science.
Exploratory research is "the preliminary research to clarify the exact nature of the problem to be solved." It is used to ensure additional research is taken into consideration during an experiment as well as determining research priorities, collecting data and honing in on certain subjects which may be difficult to take note of without exploratory research.
The maximum likelihood method has many advantages in that it allows researchers to compute of a wide range of indexes of the goodness of fit of the model, it allows researchers to test the statistical significance of factor loadings, calculate correlations among factors and compute confidence intervals for these parameters. [6]
A variety of salts may be added to adjust the pH and act as clarifying agents, depending on the water chemistry. These include sodium hydroxide , calcium hydroxide , aluminum sulfate , aluminum oxide , ferric sulfate , ferric chloride , sodium aluminate , with flocculant aids polyaluminum chloride , polyferric chloride . [ 17 ]