Using Respirometry to Evaluate the Impact of Macronutrient Application in Pulp and Paper Aerated Stabilization Basins, 2003 Environmental Conference Proceedings

Microorganisms consume organic matter to get the energy they need for cell maintenance and reproduction. The major chemical elements for bacterial growth are carbon (C), oxygen (O), nitrogen (N) and phosphorus (P). In the context of an ASB system, the carbon comes from the BOD in the mill effluent, the oxygen from the ASB aeration system, and the nitrogen and phosphorus from nutrient addition and benthic feedback. Nitrogen and phosphorus are collectively referred to as macronutrients, or simply nutrients, in the context of wastewater treatment.

While it is possible for bacteria to consume BOD without nutrients, the complete synthesis of new cells requires nitrogen and phosphorus in the proper amounts. Without sufficient numbers of bacteria, an ASB cannot achieve optimum BOD removal. Other problems caused by insufficient nutrient levels are well documented in the literature and include excessive filamentous organisms and polysaccharide or slime bulking.

Respirometry is the technique of measuring bacterial metabolism and respiration via dissolved oxygen uptake rates. This technique has long been used to determine the relative treatability or toxicity of waste streams in industrial wastewater treatment facilities. This paper discusses the use of respirometry for developing and optimizing macronutrient applications in pulp and paper aerated stabilization basins (ASBs). Data are presented showing the impact of both nitrogen and phosphorus on oxygen uptake, as well as results from studies evaluating the effects of varying the applied nitrogen to phosphorus (N:P) ratio for an ASB influent at a Southeastern pulp and paper mill.