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New biocide dry toilet with improved hygienic functionalities

Final Report Summary - DRYCLOSET (New biocide dry toilet with improved hygienic functionalities)

Executive summary:

In DRYCLOSET we seek three outstanding developments: a new biocide and slippery material, a new anti-struvite precipitation system and an improved biofilter.

We have obtained two specific harmless materials for the toilet. A resistant biocide polymer that can be installed in the toilet bowl, and an anti-bacteria coating that can be deployed over the toilet bowl. In both cases, the material has achieved activity of 5 logs decreasing within 24 h contacts. And also in both cases the material is active against Gram (+) and Gram (-), which includes bacteria as E. Coli, S. Aureus and K. Pneumoniae. These elements will ensure cleanness and hygiene in the toilet.

The second innovative development in the DRYCLOSET project is the identification and validation development of a solution to avoid precipitation of struvite. This material (2mM solution of urease inhibitor compound NBTT) will prevent the struvite precipitation in more than 90 % in one month. This solution should be applied every determined period of time in the pipes for avoiding blockages that could generate bad performance of the toilet. Testing in real toilet has shown that chosen anti-struvite liquid inhibits ureolysis.

A third successful result is the development of a biofilter with an active matrix and designed geometry to remove odours in the drytoilet in a high effective manner. UGNCleanPelletsV were developed to increase moisture content of pellets and to increase ammonia adsorption capacity of filter material. It contains 20 % of vermiculite. The effectiveness of UGN product UGNCleanPelletsB, containing similar material as UGN CleanPelletsV, but without vermiculite, was also tested. Both UGNCleanPelletsB, already commercially available, and UGNCleanPelletsV, developed in DRYCLOSET project, can meet treatment objectives set in description of work. E.g. removal efficiency of ammonia and Volatile organic compound (VOC)s has been more than 99 %, when 60 s contact time was used with UGNCleanPelletsB.

Biological ammonia oxidation was shown in laboratory biofilters. Growth of nitrifying bacteria needs hydrogen carbonate which is present in both UGNCleanPelletsB and UGNCleanPelletsV. Therefore, this material is very suitable for use in biofilters. Regular irrigation of filter material is necessary for removal of odorous compounds.

Two biofilter designs have been proposed assuming both natural and forced ventilation conditions. For natural ventilation conditions a biofilter has been designed and analysed using Computer fluid dynamics (CFD) with the dimensions of the Saniverte 5 toilet from Ecosphere. It has been demonstrated that it is possible to have a natural ventilated airflow in the dry toilet and to achieve the required contact time of 60s within the biofilter which lead to the efficient removal of odours.

The current solutions optimises the performance of the current toilets and hence the exploitation possibilities of the final product.

In summary, we consider the DRYCLOSET results achieved the expected objectives and these results are ready to be launched into the market. In fact, the partners in the consortium have taken already concrete actions to start the commercialisation and Ecosphere will participate in the demonstration project proposal named DRYCLOSET DEMO that has been submitted to the call Research for the benefit of Small and medium-sized enterprise (SME)s Seventh Framework Programme (FP7)-SME-2013, in the demonstration action.

Project context and objectives:

Water is essential for life. This element is also a deciding factor in the economy and ecology of every region. Water affects human life and humans also affect the water cycle. Human activity is responsible for the climate changes affecting the Mediterranean region with drought and desertification due to water shortage. Water resources in Mediterranean countries are presently a big issue. The total abstraction of freshwater across Europe is around 288 km3 / year and represents, on average, 500 m3 per capita / year. Overall, 44 % of the total abstracted is for energy production, 24 % for agriculture, 21 % for the public water supply and 11 % for industry. In fact, toilet flushing amounts to 25-30 % of the domestic use of urban water, about 16km3/ year or 16.329 billion litres / year. This use of water could be significantly minimised using dry toilets thus saving up to 50 litres per capita / year. In addition there are more than 20 million citizens without access to safe sanitation in Europe. This situation is critical in rural areas of eastern European countries, where the most common system consists of pit latrines and septic tanks.

Nowadays dry toilets present several shortcomings, such as unpleasant odours and the necessary manual manipulation of latrine waste, hindering their use on a big scale and therefore minimising their potential impact. There are other problems regarding struvite formation in pipe connections. All this could be changed by means of the technical innovations that will be developed in this project, namely a compact, gas specific biofilter, a struvite prevention system and a rechargeable biocidal surface. This will be particularly important in Mediterranean countries, where the drought menace is more obvious each day. The use of dry toilets in rural areas with poor infrastructure will bring safe sanitation to its citizens.

DRYCLOSET is a project devised by several European SMEs to contribute with solutions that can lighten the growing menace of water shortage in some European countries and the risks associated with unsafe sanitation. The technological approach will consist in obtaining dry toilets that overcome the shortcomings of current dry systems, thus allowing for big scale industrial implementation. The use of standard toilets that need water to work implies the waste of a significant amount of drinkable water. The water saved due to a widespread implementation of dry toilets would be a great help to save drinkable water, and will give previously unavailable access to safe sanitation to a high number of citizens.

In addition, there is a clear impact of drought events in the economy, it possible to estimate the direct economic impact in the past thirty years at a minimum of EUR 100 billion. It should be noted that major consume are due to toilets and shower activities. The consumption in those activities represents the 61 % of the total water consume in a normal house per day.

DRYCLOSET project aims to develop a new technology that allow to get new and efficient toilet that contributes to reduce the use of water by providing a plastic toilet with improved features that could be more acceptable by the consumer, with biocidal properties, low bad odours emissions and low maintenance.

Use of water toilets imply drinkable water waste that some countries, due to the climate change, must be avoided. Water toilets cannot be installed in some rural regions, where the pipe web and wastewater treatment plant systems are not installed, and it installation would be too expensive in economic and ecological terms. In these regions the alternative is the installation of systems such as septic tanks or dry toilets but it has some technical troubles.

The septic tanks produce H2S gas, which is very toxic and there is no way to avoid it. In this system the water consumption is necessary; you can only avoid the installation of pipe web and waste water treatment plants. Because it this is not the possible solution to apply in countries where the drought is a constant menace as is the example of the Mediterranean countries or in flooded areas.

The existing dry toilets are very rudimentary and have several limitations to implant their use for private family use. Nowadays the technology applied to dry toilets is basically resumed in urine diverted systems and composting of the solid materials.

Currently there are some technical troubles to solve in the development dry toilets:

- Bad odour production in the storage step. The fact of not using water to remove the waste makes very difficult to avoid the bad odour associated with free excrement. The provided filter is not able to remove this bad odour because of their bad selectivity to organic compounds responsible of bad odours.
- Due to the fact that this kind of toilet are not flushed with water, makes their surfaces more suitable to microbial growth, therefore it is desirable that the toilet´s surface contains a biocidic features that allow to prevent infections due to spills, leaks and splash during the defecation.
- Another problem concerns the formation of struvite deposits that block the pipe system. This problem is well known in sanitation system in cities, where the struvite formation is a problem not well solved due to the poor efficiency of the actual systems. These toilets have a urine-separating system where struvite precipitation occurs in pipes and valves conducting urine because they do not flush water to conduit the urine container.

Wider installation of dry toilets could help to lighten the clean water scarcity but need resolve the technological troubles which are limiting, by the moment, the expansion of dry toilets. It is necessary to encourage technological improvements in composting dry toilets, in order to allow growth of this market sector. With an appropriate development in the area some other industries can be beneficiated such as the pipe and wastewater industry.

The main scientific and technological objectives planned for the project are as follows:

1. Development of a biocide slippery material

- acquisition of a deeper understanding of the scientific knowledge that will be necessary for developing new polymeric materials with slippery and rechargeable biocidal activity.

2. Anti-struvite precipitation system

- the study of potential biocide compounds of urease producing bacteria and inhibitor compound;
- to develop a system to avoid struvite precipitation.

3. Biofilter improvement

- develop a new material to apply in biofilters which will enable them to be smaller and more versatile;
- study the problems associated with the election of the design parameters that characterise the efficiency of the biofilter.

4. Technology validation and integration

- to proceed with the system integration;
- to develop final product trials and field testing to validate the product;
- to carry out a full cost analysis.

Project results:

In terms of performance we may report in DRYCLOSET we have obtained two specific harmless materials for the toilet. A resistant biocide polymer that can be installed in the toilet bowl, and an anti-bacteria coating that can be deployed over the toilet bowl. In both cases, the material has achieved activity of 5 logs decreasing within 24 h contacts. And also in both cases the material is active against Gram (+) and Gram (-), which includes bacteria as E. Coli,S. Aureus and Klebsiella pneumoniae. These elements will ensure cleanness and hygiene in the toilet.

On the other hand, a 2mM solution of urease inhibitor compound NBTT, available commercially for agricultural use, has been identified as the optimum solution to be developed. This material will prevent the struvite precipitation in more than 90 % in one month. This solution should be applied every determined period of time in the pipes for avoiding blockages that could generate bad performance of the toilet. Testing in real toilet have shown that chosen anti-struvite liquid inhibits ureolysis but the dosage of anti-struvite liquid needs to be increased in real conditions. This is due to presence of fecal matter in urine in real conditions.

Finally, UGN CleanPelletsV was developed to increase moisture content of pellets and to increase ammonia adsorption capacity of filter material. It contains 20 % of vermiculite. The effectiveness of UGN product UGNCleanPelletsB, same as UGNClenaPeletsV without vermiculite, was also tested. Both UGNCleanPelletsB and UGNCleanPelletsV developed in DRYCLOSET project can meet treatment objectives set in DoW. E.g. removal efficiency of ammonia and VOCs has been more than 99 %, when 60 s contact time was used with UGNCleanPelletsB. Biological ammonia oxidation was shown in laboratory biofilters. Growth of nitrifying bacteria needs hydrogen carbonate which is present in both UGNCleanPelletsB and UGNCleanPelletsV. Therefore, this material is very suitable for use in biofilters. Regular irrigation of filter material is necessary for removal of odorous compounds. Two biofilter designs have been proposed assuming both natural and forced ventilation conditions. For natural ventilation conditions a biofilter has been designed and analysed using CFD with the dimensions of the Saniverte 5 toilet from Ecosphere. It has been demonstrated that it is possible to have a natural ventilated airflow in the dry toilet and to achieve the required contact time of 60s within the biofilter which will lead to the efficient removal of odours.

Potential impact:

DRYCLOSET has developed a new toilet device (Dry Toilet) with less maintenance and better functionalities.

This product will help ECOSPHERE to expand their market toilet devices for dry toilets systems through the integration of the new biocide materials, anti-struvite system and the biological filtration of the 'polluted' air.

ECOSPHERE will exploit the new toilet device in the industrial sector related to sanitation and installation of dry toilets.

The exploitable results have been identified:

- anti-struvite solution;
- new polymer material;
- new biofilter (design and material).

ECOSPHERE will expand their market toilet devices for dry toilets systems through the integration of the new biocide materials, anti-struvite system and the biological filtration of the 'polluted' air.

Thanks to the new formulation for the polymeric material, active against Gram (+) and Gram (-), which includes bacteria as E. Coli, S. Aureus and Klebsiella pneumoniae, REPOL will diversify their portfolio in the market of biocide plastics and devices made of, oriented to polymers with rechargeable properties such as biocide ones. These elements will ensure cleanness and hygiene in the toilet which will also benefit ECOSPHERE products.

TECNOVE will have access to a new range of products with new functional features.

A third successful result is the development of a biofilter with an active matrix and designed geometry to remove odours in the drytoilet in a highly effective manner. UGNCleanPelletsV were developed to increase moisture content of pellets and to increase ammonia adsorption capacity of filter material. It contains 20 % of vermiculite. UGN will expand their portfolio in biofilter for excreta treatment plant.

Some dissemination activities took place during the project period:

- start up and up-dating of the web page of the project: http://www.drycloset-project.eu/
- preparation of diverse brochures and flyers presented in fairs, dry toilet exhibitions, inaugurations of Ecosphere's dry toilets;
- preparation of posters and communications in conferences and workshops;
- preparation of scientific papers and newsletters: Sustainable technologies and research for European aquatic management (STREAM) quarterly newsletter (see http://stream-project.eu/newsletters online for further details);
- participation in the following events:

(i) Conferences and exhibitions

(a) 27-30 November 2012: Pollutec Horizons - Today's exhibition for tomorrow's solutions to environmental and energy challenges, Paris-Nord Villepinte, France.
(b) 20-22 November 2012 - Salon des maires et des collectivités locales, Paris - Porte de Versailles, France.
(c) 22-25 August 2012 - Dry Toilet 2012, The 4th International Dry Toilet Conference, Tampere, Finland (see http://www.drytoilet.org online for further details).
(d) 25-27 June 2012 - Ecotechnologies for Wastewater Treatment Conference, Santiago de Compostella, Spain (see http://www.novedar.com/ecoSTP/ online for further details). (e) 25-27 April 2012 - SAM 2012, Alpexpo, Grenoble France, 25-27 April 2012.

(ii) Dry toilet Inaugurations

(a) Inauguration of a drycloset in Nyons (France) : 24 June 2011
Principle participants: Mayor of Nyons, President of the Drôme General Council, officials

(b) Inauguration of a drycloset in Dieulefit (France) : 8 July 2011
Principal participants: Mayor of Nyons, President of the Drôme General Council, Mayor of Dieulefit, Director of Huttopia, others official

Project website: http://www.drycloset-project.eu/