On line chemical analysis has been developed significantly thanks to digital electronics' use of microprocessors together with the application of sophisticated and accurate analytical techniques.
The result of this combination is readily available technology which allows for on line performance of almost any analytical determination for quality control which is normally made in a laboratory. Moreover it allows for the automation of traditional chemical analyses generally considered difficult to do if not manually.
Correct monitoring can only be obtained utilizing sophisticated and modular instrumentation (with capacities of auto-diagnostics, auto-calibration, alarms) which can be easily and efficaciously maintained and repaired.
It is important not to forget the collateral aspects of analysis, i.e. proper sampling and preconditioning of the sample as well as proper data collection.
It is also very important that technicians are available for maintenance and control of the operation of the analytic system .
Nutrients in water
In water analyzed for environmental purposes such as industrial, civil, surface (rivers, lakes, seas) waters, some very important substances can be verified; namely nutritious matter or nutrients.
These are: organic substances, nitrogen compounds (ammonia, nitrates, nitrites) and phosphor (total phosphor or orthophosphate). These substances are called nutrients because they promote the growth and development of several types of microorganisms which are present in water.
In waste water treatment plants, nutrients are fundamental because they assure the greatest growth of microorganisms and consequently the best aerobic and anaerobic treatment
The ideal amount of nutrients in waste waters is normally considered to be the ratio of carbon: nitrogen; phosphor = 100:5:1. The lack of nutrients in waste water, particularly in industrial waters, together with other factors (pH, low dissolved oxygen levels) may promote the growth of undesirable microorganisms which cause plant inefficiency (thready microorganism growth -sphaerotilus, leptotrix, beggiatoa; mold which causes sludge explosion).
The presence of nutrients in surface waters also causes algae growth which diminishes dissolved oxygen. The river therefore becomes poor in oxygen and consequently in animal life. Nutrient control is becoming more and more fundamental to treatment plants' ability to manage and limit pollution.
The total amount of organic matter in water is called the ''organic load' and by definition consists of chemical compounds containing carbon atoms (aliphatic and aromatic hydrocarbons and all of their derivatives, solvents included).
Inorganic compounds which contain carbon atoms are not part of organic load; for example carbon dioxide (CO,) dissolved in water produces carbonic acid (H,C03) and its salts which are widespread in nature (sodium, calcium and iron salts).
Other chemicals that are not part of the organic load are: monoxide (CO), bisulfide (CS), carbon tetrachlo-ride (CCI4), cyanide, thiocyanate, carbide and pure, amorphous and crystalline carbon.
On line analysis of organic in water case study