Wastewater and Effluent Parameters

Nitrates are a form of naturally occurring nitrogen compounds found in several different forms in aquatic ecosystems. Nitrates are essential plant nutrients but can cause significant water quality problems in excess amount. It can accelerate eutrophication, causing dramatic increases in aquatic plant growth and thus, affects dissolved oxygen, temperature, and other indicators. Nitrate can be measured by nitrate-selective electrode meters.

Fluorine is a natural trace element and exists in almost all soils. Fluoride is classified as any binary compound of fluorine with another element. Perhaps the most widely known use of fluoride is its addition to public drinking water supplies at about one milligram per liter (mg/L) of a fluoride salt, measured as fluoride, for the purpose of reducing tooth decay.

Dissolved Oxygen (DO) refers to the level of free, non-compound oxygen present in water or other liquids. Oxygen is perhaps the most well-established indicator of water quality. It is an important parameter in assessing water quality because of its influence on the organisms living within a body of water.  A dissolved oxygen level that is too high or too low can harm aquatic life and affect water quality. DO can be measured through classical method of azide modification or by membrane-electrode DO meters.

Cyanide is a carbon-nitrogen chemical unit which combines with many organic and inorganic compounds. It is an extremely toxic substance that is produced naturally and artificially. Cyanides are generally not persistent when released to water or soil, and are not likely to accumulate in aquatic life. But high levels of cyanides can cause rapid toxicity among aquatic life. One of the easiest and cheapest method available for the determination of cyanide concentration is the cyanide-selective electrode method.

The presence of dissolved natural organic material, usually from aquatic humic matter, causes water to have color. Certain industries rely to the aesthetic appearance of water suitable for their industrial applications. Color may also affect photosynthetic processes of some underwater plants and algae which may interfere sunlight to pass through. The standard method for color of water is the platinum-cobalt method.

Chlorides are salts resulting from the combination of the gas chlorine with a metal. Chlorine alone as Cl 2 is highly toxic and it is often used as a disinfectant. In combination with a metal such as sodium it becomes essential for life. Small amounts of chlorides are required for normal cell functions in plant and animal life. But excessive amounts of chlorides can also be harmful, such that it can corrode metals and affect the taste of food products. It can also contaminate freshwater streams and lakes. Some aquatic animals cannot survive in high levels of chlorides. By using chloride-selective electrode meters, concentrations of chlorides can already be measured accurately.