We wanted to get more information about the local tube cleaning processes and issues. Therefore the iGEM-Team Stuttgart interviewed the tube cleaner company Rohr-Fuchs (abbreviated RF in the interview), what can be translated as pipe-fox, on the reasons of clogged drains and on their opinion on our genetically modified biological tube cleanser and the alternative using chemical tube cleaners.

iGEM-Team:

What is your first idea when you hear the word genetic engineering. Do you connect positive or negative associations with this term?

RF:

My first thought is about external influence on DNA. Generally, artificial interferences with complex biological systems are negative connoted due to the difficult predictability. However, if this technique is responsibly used there may be great opportunities.

iGEM-Team:

What is generally your opinion on our biological tube cleaner which is based on a holistic approach using E.coli?

RF:

Generally, this idea seems to be laudable, nevertheless, our experiences on working with lipases showed that applied microorganisms can be a thread to other organisms. Similar experiments led to breakdowns of sewage treatment plants in the past. That is why we remain skeptical about the benefits of such a biological tube cleaner so far.

iGEM-Team:

Is it possible that chemical tube cleaners cause environmental problems?

RF:

We are convinced of that. Aggressive and small molecular components are difficult to neutralize. Furthermore, sewage treatment plants work with microorganisms as well, which have to struggle especially with chemicals in waste water. Another aspect would be that these aggressive chemicals corrode the sewage pipes, damaging them what is followed by the release of such chemicals into the ground water. iGEM-Team:

Do you think that chemical tube cleaners can be the cause of damages in the pipe systems?

RF:

Definitely! Many pipes are made of plastic nowadays and consumers usually use these chemical substances only until the blockage is already there, although, the instructions of such agents usually recommend a prophylactic use. Consequently, these aggressive chemicals cannot flow off causing large quantities of these chemicals to stay in the pipe which get corroded then by the chemicals. Even our metal spirals get damaged by these chemical agents.

iGEM-Team:

These chemical tube cleaners contain substances such as nitrate, sodium carbonate and aluminum components. Can these substances cause problems, as we already have – e.g. in case of the nitrate – to much nitrate in (German) ground water? What happens to the aluminum hydroxide which results from the aluminum components?

RF:

Indeed, the additional nitrate is a problem for the ground water. Same applies for the other aggressive components of chemical tube cleaners.

iGEM-Team:

What do you think is the biggest problem in case of drain cleaning? Which substances, materials or blockages are a risk? RF:

As described before we do not recommend corrosive liquid cleaner. Especially, tube cleaner in granule form should not be used as it accumulates in front of the blockage, swells and gets hard as concrete. Consequently, these substances are counterproductive and even complicate our work then. Blockages are often caused by non-soluble textiles which should be disposed in waste containers and never in the toilet. Furthermore, thin objects such as cotton swabs constitute a big burden for our sewage treatment plants as they are too thin to be removed by the filter system. If large amounts of fat get in to the drain system and it is not rinsed or only rinsed with cold water, fat accumulates till the pipe is totally clogged. Generally, always rinse with lots of water in case of removing any solid materials in the sink.

iGEM-Team:

What do you think about the commercial biological tube cleaners. Are they efficient?

RF:

Generally, we strongly advise against all tube cleaners due to environmental reasons, as they are an additional burden for the sewage treatment plants and the ground water.

iGEM-Team:

How do you proceed in the drain cleaning? Can you explain the typical drain cleaning process?

RF:

After a local inspection we remove the siphons of the sinks or the toilette. Then spirals made of metal are inserted in to the pipe to electromechanically mill it. Thereby the blockage gets solved and is transported to the next bigger pipe where it can flow of more easily. Lots of water while milling and afterwards helps to remove the blockage as well as its cause. iGEM-Team:

Who needs your service more often, industry or households? And what does mostly cause the blockages?

RF:

Industry and households call us equally. Only the causes are different: In households, the blockages are mostly caused by hair and soap while we have to fight with fat clogged pipes in restaurants. Feminine textile products are the main cause for blockages in public toilettes and clogged pipes in the industry are mostly caused due to wrong construction work as the pipes are not made for the increased usage.

iGEM-Team:

It seems like that blockages caused by fat occur more often recently. How do you unclog such blockages? Could lipases be helpful?

RF:

It is laudable that households use less water however you should not save hot water especially in the kitchen. We often have cases in which the kitchen pipes are totally blocked by fat. Here helps only lots of warm water and patience. We cannot recommend the usage of lipases or any other chemical substances.

iGEM-Team:

Does human hair constitute a problem in pipes?

RF:

Indeed! Especially, if people complain about clogged shower or bath tub sinks we can be almost sure that hair is the main cause in these blockages.

iGEM-Team:

Would it be an advantage for the consumer if there is a fragrance produced while degrading the hair.

RF:

As long as these vapors are not harmful it can be a pleasant side effect.
iGEM-Team:

Is it possible that genetically engineered E. coli pose problems in the drain? Do you have problems with biofilms when cleaning pipes? If yes, how do you fight these biofilms?

RF:

No, we do not have such problems.

iGEM-Team: Do you know if GVOs are used to clean drains? If yes, in which way?

RF:

No, as our area of expertise is the mechanical cleaning.

iGEM-Team:

If we can make sure that the E. colis kill themselves in the drain and only enzymes such as keratinases, lipases and esterases stay in the pipe would you use the microbial tube cleaner?

RF:

If these enzymes do not attack other organisms the usage of such a tube cleaner seems to be okay. However, our area of expertise is the mechanical cleaning as this method demonstrably does not burden the sewage in any way.

iGEM-Team:

What would you like to tell consumers for a preventive drain cleaning? Which tips can you give to prevent blockages?

RF:

Do not throw any materials into your sinks which are not soluble in water. Even if they are so small that they go through the sieve, rinse thoroughly! In case of fat, use warm water for rinsing. Although toilet drains have a bigger diameter feminine hygiene products cannot be fully removed, consequently, throw these products into waste containers.