Ing Accidental Denitrification

There are several indicators of denitrification. Indicators of denitrification in the secondary clarifier include presence of numerous bubbles, rising solids that have numerous bubbles on their surface, increase in alkalinity, and possibly, pH across the clarifier, and reduction in redox potential across the clarifier. Because the atmosphere contains approximately 80 molecular nitrogen, the capture and measurement of escaping molecular nitrogen from the surface of the clarifier to demonstrate...

Temperature

Of all operational factors affecting nitrification, temperature has the most significant influence on the growth of nitrifying bacteria and, consequently, the rate of nitrification (Table 17.1). The rate of nitrification usually is expressed as pounds of ammonium ions oxidized per pound of MLVSS per day. Because nitrifying bacteria are temperature sensitive, nitrification is temperature sensitive. There is a significant reduction in the rate of nitrification with decreasing temperature and,...

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...

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...

Sources of Nitrite Ions and Nitrate Ions

Unless nitrite ions and nitrate ions are discharged to an activated sludge process in specific industrial waste streams, nitrite ions and nitrate ions that are found in an activated sludge process must be produced in the aeration tank. The production of nitrite ions and nitrate ions is achieved through the biologically mediated reactions of nitrification. The reactions involve the oxidation of ammonium ions and nitrite ions. Industrial waste streams that contain relatively high concentrations...

Zoning

Desired or intentional denitrification is usually achieved in an activated sludge process by establishing an anoxic zone or an alternating series of anoxic zones (Figure 32.1). The anoxic zone is the first corn- Figure 32.1 Alternating series of anoxic zones. In an activated sludge process that has the capability to operate in plug-flow, it is a common practice to control denitrification in the secondary clarifier by using the first aeration tank as an anoxic zone. In this practice, return...

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...