Nitrite Ion Accumulation

The production and accumulation of nitrite ions in an activated sludge process can occur during some forms of incomplete nitrification. The accumulation of nitrite ions is due to partial inhibition of enzymatic activity within nitrifying bacteria. This inhibition prevents the rapid oxidation of nitrite ions to nitrate ions. Operational factors responsible for this inhibition include cold temperature, deficiencies in key nutrients, high influent ammonium ion concentration, inhibitory and toxic...

Classification of Nitrification Systems

Nitrification systems within activated sludge processes may be classified according to the degree of separation of cBOD and nBOD oxidation or removal. The removal of cBOD and nBOD may occur in the same aeration tank or in separate aeration tanks. If cBOD and nBOD removal occur in the same aeration tank, the treatment system is termed a single-stage system (Figure 20.1). If cBOD and nBOD removal occur in separate aeration tanks, the treatment system is termed a separate-stage or two-stage system...

Introduction to Denitrification

The term denitrification was first used in France in 1886 to describe the use of nitrate ions by some bacteria to degrade substrate. The bacterial use of nitrate ions (and nitrite ions) to degrade substrate actually evolved before the use of free molecular oxygen. Wastewater denitrification describes the use of nitrite ions or nitrate ions by facultative anaerobes (denitrifying bacteria) to degrade cBOD. Although denitrification often is combined with aerobic nitrification to remove various...

Introduction to Nitrification

Nitrosomonas And Nitrobacter

Biological nitrification is the conversion or oxidation of ammonium ions to nitrite ions and then to nitrate ions. During the oxidation of ammonium ions and nitrite ions, oxygen is added to the ions by a unique group of organisms, the nitrifying bacteria (Figure 6.1). Nitrification occurs in nature and in activated sludge processes. Nitrification in soil is especially important in nature, because nitrogen in absorbed by plants as a nutrient in the form of nitrate ions. Nitrification in water is...

TABLE 141 Types of Biochemical Oxygen Demand

Flatworms Process

There are several types of BOD that enter an activated sludge process. Total BOD is the sum of all types of BOD found in the influent to the activated sludge process. Forms of particulate BOD are the solids such as cellulose that can be degraded. Much particulate BOD is removed in the primary clarifier, and unless adequate HRT is provided in the aeration tank, par-ticulate BOD is adsorbed to the surface of floc particles in the aeration tank and is not degraded. Forms...

TABLE 151 Oxygen Requirement Groups of Bacteria

CBOD removal Denitrification Floc formation Methane production in anaerobic digesters biological and operational purposes. These purposes are (1) the oxidation of cBOD to provide carbon and energy for cellular activity, growth, and reproduction (production of MLVSS), (2) oxidation of cBOD to provide energy for endogenous respiration (destruction of MLVSS), and (3) oxidation of nBOD or nitrification. Of the many operational requirements known to affect nitrifying bacteria or nitrification,...

Methemoglobinemia

Methemoglobinemia

The term ''methemoglobinemia'' or ''blue baby syndrome'' refers to the disease experienced by an infant who consumes groundwater contaminated with nitrate ions. When an infant consumes formulae made with groundwater contaminated with nitrate ions, the ions are easily converted to nitrite ions in the infant's digestive tract. The nitrite ions that enter the infant's circulatory system bond quickly to the iron in the hemoglobin or red blood cells (Figure 1.4). Figure 1.4 Methemoglobinemia. If...