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Over a period of about 30 years, Prof. Helmut Löffler at the TH Dresden, Germany, under the authoritative co-work of Dipl.-Ing. Dieter Burschil adapted the principle of sewage treatment to sewage treatment plants of a type which, with the help of plants, achieves a cleaning performance which is comparable to the commercially operated large-scale plants, which is much lower in operating costs. In fact every question raised in this context was scientifically investigated and the answer was scientifically supported.

Prof. Löffler originally developed these sewage treatment plants as a self-assembly kit for smaller farms, farms etc. with few people living there. The team of PFC project, mainly project manager Hansjürgen Gase, has succeeded in implementing these installations on a larger technical scale for a whole community with 600 inhabitants and to pass through the approval process.

The resulting plant is the largest of its kind in Germany and has now been in operation for more than 15 years. It is under permanent, thorough monitoring by the TÜV and various authorities.

The cleaning performance achieved was so excellent in many years that the inspection report of the TÜV shows a BOD value of "<3 or not measurable".

The IBK is currently working on the further large-scale implementation of this environmentally friendly and cost-conscious way of clarifying sewage water.

The target areas are predominantly rural areas without existing own infrastructure such as India, parts of Spain, Vietnam and the like.

We are in constant contact with Hansjürgen Gase of the PFC Project in Leipzig and are glad that Prof. Löffler is always friendly to us in individual technical matters. Almost every subject in this context was scientifically investigated and the correct answer was found.

What does "wastewater treatment" or "recycling" mean when it comes to household wastewater? In or treatement process we make water reusable, hence our water treatment is among a broad range of specialsied techniques a water clarification process. Here's a brief introduction to the subject:

Drinking water

Apart from the basic building block H2O, drinking water consists of additions of lime and mineral salts. More so, drinking water should be clear of opacifying co-formulation agents, even if they are biochemically harmless. "Biological additives", i.e mainly bacteria, should not be included either in drinkng water, and this is where water differs from sewage, as sewage carries biological additives.

For drinking water, in Europe, the enterprise of treating drinkable water is subject strict regulations that limit values ​​for individual co-formulation agents. Perfectly clarified (cleaned) wastewater means that you can or could drink it as there is no immediate risk of infection. Nevertheless, drinking water is not permitted in the sense of the regulations. This is not an advantage, but it depends on the applicable regulations of the location.

Water for domestic hygiene

Water for cleaning and irrgation, as well as for showering and bathing, does come into contact with human skin, but it is not as strictly regulated as designated drinking water. This is mainy due to the non-oral use of the water. 

Domestic sewage

Domestic wastewater contains bacteria, i.e. organically active components which, in addition to the bad smell, can cause or transmit diseases. 

EEC = Quantity of domestic wastewater

In this context the concept of the EEC must still be explained. EWG (Amount of wastewater per person per day) is German for "inhabitant equivalence" and means the amount of domestic wastewater that is caused by one inhabitant per day. In terms of German regulations, this value is around 90 liters per day. This amount of daily wastewater includes not only direct water consumption from cooking, personal hygiene and toilet flushing, but also indirect water consumption from car washing, watering plants, etc. 

This value, multiplied by the number of inhabitants to be connected, is decisive for the design of a system and should be significantly lower in accordance with the actual conditions in African countries. 

Inorganic co-formulants

Our treatement processes limit the use of inorganic components such as drug residues and mineral oil products. These do not belong in domestic sewage and also cause major problems for large municipal sewage treatment plants.

Scientific limits: BOD (and COD)

In order to make organic pollution generally measurable, science has come up with the so-called BOD value, which is internationally recognized. This is a total value for the oxygen that is required in order to "burn" or oxidize all organically active component, in particular bacteria, that are still present in the wastewater; the best BOD value water can be tested for is 0.0. The COD is defined a little differently, but basically says the same thing.  

Note: a bacterium that has been oxidized in this way is still physically present after the oxidation, as it were as a corpse or dead suspended particle. But it is no longer biochemically reactive and therefore harmless. 

limit values BOD

For comparison: the highly concentrated wastewater from pig fattening has a BOD of approx. 5,000; the so-called domestic wastewater, which is heavily diluted by showering has a value of 500. Ideally, this input value is reduced in sewage treatment plants to 0.0 where possible, providing a quantifiable measure of "clean". The limit for bathing water according to the European standard (in which infants can be bathed or they drink) is a BOD of approx. 70. 

Good sewage treatment plants manage 20 to 30 BOD values, compared to our model plant which offers a value of "0 or not measurable or <3" according to official protocols.

Optical clarification = particle filtering

After lowering the BOD, the task remains to make the water as clear as possible; But this is pure filter technology and has nothing to do with the biologically active substances (germs). Note: not every cloudy broth is also harmful to health. Conversely, the clarity of water does not mean that it is harmless to health.

Alternative approaches

There are loads of approaches to the (re-) use of contaminated water (fresh or already used) after some clarification. These depending on the area of application and the intended purpose, the methods may well have their right. A simple example is the famous tablets that you take on a trekking tour across Asia or seawater desalination tablets for circumnavigators. And certainly the mobile container solutions used by the American armed forces for water treatment fulfill their purpose, but the gas turbine for the energy supply is in the container next door.

Something like this works for limited use, but it is not a cost-effective permanent solution. A good example are the actually highly efficient activated carbon filters: they manage the disinfection but only as long as they are new or within their maintenance cycle. The carbon filters have to be replaced and this is the problem that arises with all filter solutions: everything looks intact on the outside and the internal fixture of the filter overtime becomes a bacterial den. 

The problem with all filter solutions is that constantly replacing the filter costs money and that adds up - extrapolated to a community. A biological sewage treatment plant of our type would involve less operational costs and life span maintenance. 

For example, it is also possible to work with UV irradiation to reduce the BOD by oxidation, but this method costs the high production costs for corresponding UV systems permanently. A solution which, for reasons of cost, does not exist precisely in developing countries. Membrane osmosis-based systems have a problem with the durability of the membrane.

Summary

As a result, it can be said that apart from the optical clarification = elimination of suspended particles the reduction of the BOD value in direction 0 is indispensable for a (re) use of the water in the hygiene area and as drinking water no matter how this is done. This is a basic rule, which applies from the activated carbon filter through our biological sewage treatment plants to the municipal large-scale plants. (The biochemical oxidation processes are always the same)

Fats and mineral oils are problematic for sewage treatment plants; these must already be stopped in the inlet by means of appropriate monitoring devices or separation devices since they damage the bacterial cultures of clarification processes. Non-oxidable additives such as drug residues and similar substances can be tolerated in small doses as long as the process water is only used for body hygiene but not as drinking water.

the plant size

The question is, therefore, only how small the basically common principle can be packaged and what the implementation costs in (a) production / procurement and (b) in ongoing operating costs.

small plants for 3-4 inhabitants

Prof. Löffler, who has now emerged from the University of Dresden, has been thinking about this topic for more than 30 years. Prof. Löffler, with whom we a friendly relationship, has originately developed the type of biological treatment plants on a reed bed basis, redeveloped by us. First of all, it was specially designed for very small needs: small farms without an external sewage connection with 3-4 inhabitants. These small systems were designed as self-assembly sets: the inhabitants finally get a building instruction and can build themselves. (Prof. Löffler is still regarded as one of the leading German "sewage experts".)

further reductions

In attempting to carry out the biochemical process of oxidation in an even smaller space, we are very cautious in optimism, for the necessary surface is necessary, and in our case this consists of the surface of sand-globules, which is summed together. Take a surface area of only 10 m ^ 2 and calculate the total surface area of the sand if the total thickness of the sand layer is 1.6 m and the diameter of the individual sand ball is assumed to be 0.4 mm. The resultant surface is huge and on this surface the oxidation necessary for the reduction of the BOD takes place.

In principle, the choice of the method should be based on: 

1. The type of contaminated water to be processed and, 

2. What treatment goal is to be achieved: is it sufficient to obtain water for industrial cleaning purposes, or drinking water quality and if YES to either of these conditions, 

3. Then we adapt our design process according to the local water infrastructure regulations to produce the treated water as per its intended use.  

Low Cost

The costs of the methods in question as well as soft factors such as technical failure safety must be taken into account. Technology ideally makes systems efficient, but it is also expensive and more susceptible to failure than the use of approaches that use nature's mechanisms and organic processes of action alone: ​​nature gets the work done, and to our benefit, (almost) for free. 

After weighing up all the relevant criteria, we decided to base our water treatement solution on the natural material and harness its organic forces and techniques. Both the quality of the results and the costs, especially in areas where money and water are scarce resources, show the feasibility as well as the viability of this eco-friendly biological approach.  

Minimal Technology - minimal risk 

Minimal technology equals minimal system failures: our systems have an electric pump as the only active component that runs in a clocked manner and pumps water. In areas without a power supply, if there is a slope height difference of approx. 3 m, this pump can also be replaced and the system can be operated without electricity.

Water loss through vaporization

The plants used, i.e. usually  reeds, carry part of the water to be fed into the air via their leaf surface. This proportion depends on the type of plant and the site conditions and can be up to 30% or more. Whether this is a disadvantage or an advantage depends on the goal or approach. If such a system is used as a so-called soil filter for the infiltration of polluted rainwater (airports, highways and other sealed surfaces), this return of the water to the environment is more of an advantage. In addition, the quantity of water loss is put into perspective by the comparative loss in conventional systems, in which losses of 20-30% occur due to leaks in the public sewer. Conventional sewage treatment plants lose water through evaporation over the large surface of the clarifier.  

Plant sewage plants

The plant-based sewage treatment plant page is specifically about the approach we use. The presented high cleaning performance is confirmed there. The reference to the high space requirement on this page is countered by the fact that the technology specially developed by Prof. Löffler made it possible to clarify in three phases in bed areas, which normally extend horizontally on the surface of the earth, deep below one another to be stacked, so that the result is only 1/3 of the space normally required. 

Our systems therefore build in depth instead of in surface. In the calculation, this leads to the fact that building on an area with single-family houses with a plot size of 1,000 sqm and an average of 3 residents, which 3 EEC, results in a space requirement of around 3% of the total area.  

Degradation of nitrates

This topic has been given a special focus on the topic of denitrification, that is, the conversion of nitrate to molecular air nitrogen, since this is a central theme, particularly in the field of agriculture.

The knowledge of the functional mechanisms of wastewater treatment has become industry wide common with international standards regualting practices. So, what makes Kaufmann Engineering SA different and a better choice?  

The answer: It's a bit like in engine construction; every manufacturer knows how to do it, but there are still differences in the power output, the reliability, the speeds achieved, the long-term load capacity and other important factors in energy effeciency and sustainable engineering