What Are Filamentous Bacteria and Why Are They a Problem?
Filamentous bacteria such as Microthrix parvicella, type 021N and other filamentous organisms are a natural part of the biocenosis in wastewater treatment plants. In controlled quantities they are harmless - they even help with floc formation. However, under certain conditions, such as increased fat content in the influent or insufficient oxygen supply, they can multiply excessively. The result: bulking and floating sludge.
Conventional control strategies such as the regular addition of precipitants are often costly, unsustainable and not always effective. Without regular monitoring, the growth of bacteria goes unnoticed until it causes visible problems.
VIT® gene probe technology enables the precise identification and quantification of microorganisms directly in wastewater. Microbiological wastewater monitoring enables targeted control of measures, optimum dosing of precipitants and preventive avoidance of bulking sludge.
Efficiently Combat Bulking and Floating Sludge
Without precise data on the causes and exact knowledge of the type of bacteria causing the problem, control strategies can be ineffective or even counterproductive. Each type of filamentous bacteria requires specific countermeasures. For example, Microthrix parvicella responds positively to an increase in oxygen levels and the targeted addition of precipitants such as polyaluminum chloride (PAC). In contrast, bacteria such as type 021N require an adjustment of the sludge parameters in order to be effectively controlled.
However, conventional analytical methods such as microscopic examinations or staining techniques do not provide reliable results. The morphovariability and similar morphology of the filamentous bacteria make their clear identification difficult. PCR analyses are also problematic, as they cannot distinguish between living and dead microorganisms and the complex composition of wastewater samples makes reliable quantification impossible.
The VIT® gene probe technology overcomes these limitations by enabling accurate identification and quantification of microorganisms through its unique and direct approach.
Microthrix parvicella
These filamentous bacteria can be controlled by reducing the fat supply in the wastewater and increasing the oxygen content to over 2 mg/L in all aerobic zones in combination with increasing the sludge age. In addition, the addition of aluminum salts or iron (III) salts can be helpful to promote the precipitation of phosphate and thus worsen the nutrient conditions for the bacteria.
Thiothrix spp. and type 021N
Type 021N: Increasing the sludge load and the F/M ratio with adjustment of the sludge age and phosphate precipitation.
Thiothrix: Use of sulphur-binding chemicals such as iron(III) chloride to bind hydrogen sulphide and control the bacteria.
Haliscomenobacter hydrossis
Can be controlled by increasing the sludge load and improving the oxygen supply. The addition of certain precipitants, such as aluminum salts or iron (III) salts, can also help.
Nocardioform actinomycetes
Possible control through the reduction of grease in the inlet as well as through the use of precipitants such as aluminum salts or iron (III) salts. Improved aeration and an increase in the sludge load are also effective. In addition, the addition of surfactants can promote the separation of bacteria from the surface.
Practical Examples: AZV Südholstein / Hetlingen Sewage Treatment Plant
- Challenge: Recurrent bulking sludge due to Microthrix parvicella with sludge indices above 200 ml/g.
- Solution: Introduction of VIT® gene probe technology, which optimized PAC dosing and enabled an early response.
- Result: Reduction of the sludge index with simultaneous reduction of operating costs.
The Hetlingen wastewater treatment plant has been using direct monitoring of microbiology by means of gene probes since 2004. In this way, the sewage treatment plant can start to combat bulking sludge as soon as there is a slight increase in the disturbing filamentous bacteria in order to prevent a critical increase in filamentous bacteria and a deterioration in the discharge values. This has made it possible to permanently reduce expenditure on PAC and at the same time reduce the burden on the environment.
Why Is Microbiological Wastewater Monitoring with VIT® so Important?
Direct Analysis
Fluorescence-labeled gene probes enable the specific identification and quantification of living cells - regardless of their morphology.
The microorganisms are detected even at the lowest concentrations, long before they cause bulking sludge.
Targeted Measures
The analysis provides precise data on the type and quantity of bacteria, which enables exact dosing of precipitants. Data is available within a few hours, which enables early intervention.
Efficiency and Environmental Protection
Optimized dosing of precipitants reduces costs and improves operating efficiency. Reduced use of chemicals relieves the environment and protects the plant's biocenosis.
Regular monitoring with VIT®
Regular monitoring with VIT® allows the filaments to be tracked in a highly specific manner. Countermeasures can be initiated even before visible problems such as bulking and scum formation occur.
Regular monitoring can be carried out directly on the system with the products or as a service in the form of our annual packages, which offer an optimum price-performance ratio.
VIT® test kits recommended by experts
VIT® Chloroflexi / 1851
Test kit for rapid and quantitative analysis of the problem-causing Chloroflexi filamentous bacteria and parallel Eikelboom type 1851 in wastewater samples.
VIT® Haliscomenobacter
Test kit for rapid and quantitative analysis of the problem-causing filamentous bacteria Haliscomenobacter hydrossis in wastewater samples.
VIT® Microthrix
Test kit for rapid and quantitative analysis of the undesirable filamentous bacterium Microthrix parvicella in wastewater samples.
VIT® Nocardia
Test kit for the rapid and quantitative analysis of nocardioform actinomycetes, a group of filamentous bacteria, in activated sludge samples.
VIT® Nostocoida limicola II
Test kit for rapid and quantitative analysis of the filamentous bacteria Nostocoida limicola II and Alysiosphaera in wastewater samples.
The Advantages of Monitoring with VIT®
effective direct monitoring of the microorganisms | |
continuous monitoring of the relevant process engineering parameters | |
early detection of deviations and faults | |
enables targeted process control | |
increased operational reliability and stability of the wastewater treatment plant | |
cost reduction thanks to timely and efficient use of countermeasures | |
sustainable optimization of treatment performance |
Without VIT® Monitoring | With VIT® Monitoring | |||
|---|---|---|---|---|
| Poorer discharge values: Deterioration of sedimentation and pollution of the receiving water. | Efficiency: Targeted measures thanks to precise data. No unnecessary experiments, no waste of resources. | |||
High operating costs: Due to high addition of precipitants such as PAC or aluminum salts. | Cost savings: Optimized PAC dosing and fewer operational interruptions. | |||
Environmental impact: Due to high use of chemicals, which pollutes the wastewater treatment plant and the environment. | Environmental friendliness: Minimized use of precipitants reduces the impact on the biocenosis and the environment. | |||
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