Biosolutions Newsletter
 

                               Vol. 3, Issue 10,  March  2003

Contents

1.  Nitrification Makes for Good Regulatory Relations/Troubleshooting Guide

2.  New Drain and Trap Cleaners

3.  High Efficiency Floating Aerators

4.  Powerpoint Presentations and Application Guides  Available

5.  Next Issue

6.  Feedback

Introduction
In a typical wastewater treatment plant, nitrification – the reduction of ammonia to nitrogen oxide salts – is the icing on the cake. It occurs when the biomass is healthy and the plant is functioning at top efficiency. It is also the first to go when the plant is hit by cold weather or an influx of toxic and inhibitory compounds (such as antifreeze, for example).  Most nitrifying bacteria are sensitive to low temperatures.  Winter can thus produce a double whammy on either municipal or industrial wastewater treatment plants, resulting in out-of-permit effluents and potentially toxic discharges.

Attacking the Problem
The cold weather problem can be attacked in several ways: directly, by bioaugmentation with microorganisms selected for their ability to nitrify ammonia, or indirectly by improving the overall performance of the plant by adding microorganisms that degrade the toxic and inhibitory compounds that interfere with the native nitrifying populations, or by doing both.

An Example
The first, or direct, approach was successful recently in a 3 MGD municipal treatment plant receiving high volumes of industrial and food processing wastes. Cold weather caused ammonia-nitrogen content in the aerated lagoon to exceed the 3 mg/l permit limit. Addition of ammonia-oxidizing bacterial strains, in the form of MICROCAT®-XNL Nitrifying Microbes, to the second of the two lagoons, connected in series, plus pH control using soda ash, improved removal rates to 83% versus 51% and 43% during previous winters when lagoon temperatures typically fall to 10 to 14 degrees C (see chart.) MICROCAT-XNL was added directly to the second aerated lagoon using a chemical pump system housed in an insulated shed to prevent the water-based microbial suspension from freezing.  Prior to addition to the system, ammonia-nitrogen content in the effluent averaged 2.85 mg/l during bioaugmentation when influent levels averaged 17.41 mg/l.  MICROCAT-XNL is a blend of ammonia-oxidizing bacterial strains found in nature and is formulated for use in wastewater discharge generated by chemical, food processing, petroleum refining, textileand other industries generating wastes with a high level of nitrogen, as wellas municipal plants.

Process Control
Because there may be many causes of poor nitrification, it would be a good idea to consult the Bioscience, Inc. technical staff for recommendations to overcome a specific problem, whether caused by cold weather, inhibitory compounds, or a combination of factors. Nitrifying bacteria are delicate organisms,comparatively speaking, and, thus, require tighter control over process conditions to enable their continued growth and performance.