Euro-CASE European Council of Applied Sciences and Engineering 28. rue Saint Dominique-75007 Paris-france Te:+33153595340-Fax:+33153595341 E-mail:mail@euro-case.org-www.euro-case.org Euro-CASE Workshop: Wastewater as a resource Institut de france, paris, 7 July 2000
Euro-CASE European Council of Applied Sciences and Engineering 28, rue Saint Dominique - 75007 Paris - France Tel: +33 1 53 59 53 40 - Fax: +33 1 53 59 53 41 E-mail: mail@euro-case.org - www.euro-case.org ________________________________________________________________ Euro-CASE Workshop: "Wastewater as a Resource" Institut de France, Paris, 7 July 2000
Content Overview Wastewater as a resource- what are the options? Prof H Odegaard (N), Norwegian University of Science and Technology, Trondheim, Norway Reuse/recycling of reclaimed wastewater Achievements and challenges in the reuse of reclaimed wastewater Prof R. Mujeriego(E), ETS Ingenieros de Caminos, Barcelona, Spain Recycling of treated wastewater for agricultural and landscape irrigate treatment options and challenges 14 Prof. G. Oron(IL), Ben-Gurion University of the Negev, Israel Recycling of treated wastewater for industrial reuse-treatment options and challenges Prof L. BonomoD), Politecnico di milano, Italy Recycling of treated wastewater for indirect potable and urban reuse -treatment options and challenges Prof. Takashi Asano, University of California, Davis, USA Public health aspects in wastewater reclamation, recycling and reuse -treatment options and challenges Prof J. Bontoux(F), Universite Montpellier, Montpellier, France Reuse/recycling of resources in wastewater sludge Challenges in the reuse of resources in wastewater sludge Dr Peter Matthews(UK), Pelican Portifolio, Cambridge, UK Use of sludge on farmland as fertiliser/soil conditioner Prof. Jens Aage Hansen(DK), University of Aalborg, Denmark The production and utilization of constructed soil conditioner/compost made from wastewater sludge and other components Dr Ing. Ludovico Spinosa(D), C NR-Nat. Res. Council, Bari, Italy Alternatives to agricultural use of sludge Prof Helmut Kroiss(A), Technische Universitat, Wien, Austria Wastewater as a resource- What is the future? Ms Valentina Lazarova(f), Suez lyonnaise des eaux
2 Content Overview Wastewater as a resource – what are the options?……………………………………………. 3 Prof. H. Ødegaard (N), Norwegian University of Science and Technology, Trondheim, Norway Reuse/recycling of reclaimed wastewater Achievements and challenges in the reuse of reclaimed wastewater……………………….. 9 Prof. R. Mujeriego (E), ETS Ingenieros de Caminos, Barcelona, Spain Recycling of treated wastewater for agricultural and landscape irrigation – treatment options and challenges …………………………………………………………… 14 Prof. G. Oron (IL), Ben-Gurion University of the Negev, Israel Recycling of treated wastewater for industrial reuse – treatment options and challenges…… 16 Prof. L. Bonomo (I), Politecnico di Milano, Italy Recycling of treated wastewater for indirect potable and urban reuse – treatment options and challenges……………………………………………………………………………………… 24 Prof. Takashi Asano, University of California, Davis, USA Public health aspects in wastewater reclamation, recycling and reuse - treatment options and challenges……………………………………………………………………………………… 28 Prof. J. Bontoux (F), Université Montpellier, Montpellier, France Reuse/recycling of resources in wastewater sludge Challenges in the reuse of resources in wastewater sludge……………………………………. 31 Dr. Peter Matthews (UK), Pelican Portifolio, Cambridge, UK Use of sludge on farmland as fertiliser/soil conditioner……………………………………….. 38 Prof. Jens Aage Hansen (DK), University of Aalborg, Denmark The production and utilization of constructed soil conditioner/compost made from wastewater sludge and other components…………………………………………………………………. 43 Dr. Ing. Ludovico Spinosa (I), C.N.R.-Nat. Res. Council, Bari, Italy Alternatives to agricultural use of sludge…………………………………………………….. 48 Prof. Helmut Kroiss (A), Technische Universität, Wien, Austria Wastewater as a resource – What is the future?……………………………………………… 53 Ms Valentina Lazarova (F), Suez Lyonnaise des Eaux
WASTEWATER AS A RESOURCE- WHAT ARE THE OPTIONS? Hallvard odegaard Faculty of Civil and Emvironmental Engineering, Norwegian University of Science and Technology(NTNU), N-7491 Trondheim, Norway. E-mail: hallvard odegaard(@byggntnu. no INTRODUCTION Control of the epidemics, especially cholera, that ravaged many of the major European cities in the middle of the 18th century, was the driving force behind the development of wastewater systems The sanitation conditions had become a threat to the urban human health. Since the introduction of centralised water supply and sewerage systems, the cities of Europe has, however, been essentially free of water-borne epidemics. Around the middle of the 19'th century, discharges of wastewater (sewage as well as industrial waste)for the ever expanding industrialised society, resulted in unacceptable pollution in receiving waters, threatening aquatic life as well as human health. The cceptance of the need for pollution control, leads to the construction of wastewater treatment plants. Today these are taken for granted as part of the infrastructure of a city. Even though people living in the countryside did not experience the epidemics development caused by poor sanitation to the same extent as the cities did, centralised wastewater systems were also established for small communities and villages. Even in scattered dwellings the convenience of using water toilets lead to small on-site wastewater systems that required treatment With respect to management of the water resources, the links between the cities and the countryside become ever more evident. The wastewater treatment plants produce sludge and this sludge has to be taken care of in the countryside somehow. The countryside needs water to produce food for the cities, but the cities water is used by the cities that are also polluting the water. This clash of interests has lead to the focus on" Sustainable Urban Water Systems'". Two schools of thought have eme 1. The present centralised wastewater systems are unsuitable in the future and should be replaced by alternative systems based on local handling 2. The present system is the only realistic one in an urban environment and will be maintained in foreseeable future, but it should be modified to be more in agreement with the principles of sustainable development It is very difficult to comprehend how Europe can meet the vast economical consequences of a total system change. Therefore, we have to take our present system as the stepping-stone for a development towards a more sustainable society. Wastewater has traditionally been looked upon a problem or waste. This work-shop aims at showing that wastewater should rather be regarded as a RESOURCES IN WASTEWATER There are principally 3 resource components in wastewater 1. The water itself 2. The heat of the water(energy 3. The constituents in the wastewater(primarily nutrients and carbon
3 WASTEWATER AS A RESOURCE – WHAT ARE THE OPTIONS? Hallvard Ødegaard* * Faculty of Civil and Environmental Engineering, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway. E-mail: hallvard.odegaard@bygg.ntnu.no INTRODUCTION Control of the epidemics, especially cholera, that ravaged many of the major European cities in the middle of the 18’th century, was the driving force behind the development of wastewater systems. The sanitation conditions had become a threat to the urban human health. Since the introduction of centralised water supply and sewerage systems, the cities of Europe has, however, been essentially free of water-borne epidemics. Around the middle of the 19’th century, discharges of wastewater (sewage as well as industrial waste) for the ever expanding industrialised society, resulted in unacceptable pollution in receiving waters, threatening aquatic life as well as human health. The acceptance of the need for pollution control, leads to the construction of wastewater treatment plants. Today these are taken for granted as part of the infrastructure of a city. Even though people living in the countryside did not experience the epidemics development caused by poor sanitation to the same extent as the cities did, centralised wastewater systems were also established for small communities and villages. Even in scattered dwellings the convenience of using water toilets lead to small on-site wastewater systems that required treatment. With respect to management of the water resources, the links between the cities and the countryside become ever more evident. The wastewater treatment plants produce sludge and this sludge has to be taken care of in the countryside somehow. The countryside needs water to produce food for the cities, but the cities water is used by the cities that are also polluting the water. This clash of interests has lead to the focus on “Sustainable Urban Water Systems”. Two schools of thought have emerged: 1. The present centralised wastewater systems are unsuitable in the future and should be replaced by alternative systems based on local handling 2. The present system is the only realistic one in an urban environment and will be maintained in foreseeable future, but it should be modified to be more in agreement with the principles of sustainable development. It is very difficult to comprehend how Europe can meet the vast economical consequences of a total system change. Therefore, we have to take our present system as the stepping-stone for a development towards a more sustainable society. Wastewater has traditionally been looked upon as a problem or waste. This work-shop aims at showing that wastewater should rather be regarded as a resource. RESOURCES IN WASTEWATER There are principally 3 resource components in wastewater 1. The water itself 2. The heat of the water (energy) 3. The constituents in the wastewater (primarily nutrients and carbon )
When purifying the wastewater, one gets primarily two outgoing streams, 1)the treated water stream and 2)the sludge stream. Both of these streams contain all the three resource components mentioned above, but these resources will be utilised differently depending on in which stream they such)and the heat of the water is most important. The sludge stream is more important Wh ater(a are present. The water stream is quantitatively much larger that the sludge stream and the wa to recovery of nutrients and energy based on its carbon content carbon (biogas, heat from incineration) REUSE OF THE TREATED WATER Generally the use of water has been supply driven. As it has been an abundant commodity in most places, water has been supplied in large quantities at a very cheap price. This will have to change in therefore changing fion ns that are short of fresh water supplies. The policy of water management is the future in many regi n being supply driven to demand driven. In a demand driven situation the price of water will increase and it is possible that even extensive treatment of wastewater may turn out to be cost effective in order to produce the necessary amount of freshwater There are many possibilities for reuse of reclaimed wastewater, such as 1) for agricultural and landscape irrigation, 2)for urban reuse, 3)for industrial reuse and 4) for potable water supply. The different uses require different degrees of purity of the water, and water quality standards for this has been established (WHO, 1973, 1989). Today there are treatment technologies available that can produce reclaimed water from wastewater for these applications( Mujeriego and Asano, 1999). The greatest challenges in the reuse of reclaimed wastewater are: 1)the safeguarding of the hygienic quality, 2) the prevention of soil contamination and 3) the prevention of ground water contamination Reclaimed wastewater for agricultural and landscape irrigation In most countries the greatest demand for water is for agricultural and urban irrigation. The wastewater resource to be utilised is firstly the water as such and secondly the nutrients in the wastewater Wastewater purification at"sewage farms" was an example of zero discharge based on the"assimilative"and"self-purification power of soil(Bouwer, 1993). Even though there are a few remaining of these"sewage farms", the vast area required close to the city as well as health regulations, has made them disappear. After WHo in 1973 proposed unrealistically stringent guidelines for the quality of the effluent to irrigate crops, WHO issued in 1989 new guidelines for aqua-culture and non-potable urban uses. This new set of guidelines is controversial but has allowed a real development of wastewater reuse for irrigation purposes(WHO, 1973, 1989) Reclaimed wastewater for urban reuse Urban reuse can primarily be divided in two 1. Reuse of reclaimed wastewater for toilet flushing in dual distribution systems 2. Reuse of reclaimed wastewater for recreational lakes and brooks as well as for creation of wetlands and wildlife habitat Dual distribution systems segregate the potable water supply from the non-potable system distribution systems can be developed in two ways. One approach is to construct a city-wide sy in which the wastewater is returned to a central wastewater treatment plant for processing before being redistributed to the population to be used in the non-potable water supply system. The other approach is using small-scale individual systems where"grey"water, the wastewater from washing operations(sinkS, bathtubs, showers, wash machines) and other non-faecal wastewater is treated
4 When purifying the wastewater, one gets primarily two outgoing streams; 1) the treated water stream and 2) the sludge stream. Both of these streams contain all the three resource components mentioned above, but these resources will be utilised differently depending on in which stream they are present. The water stream is quantitatively much larger that the sludge stream and the water (as such) and the heat of the water is most important. The sludge stream is more important with respect to recovery of nutrients and energy based on its carbon content carbon (biogas, heat from incineration). REUSE OF THE TREATED WATER Generally the use of water has been supply driven. As it has been an abundant commodity in most places, water has been supplied in large quantities at a very cheap price. This will have to change in the future in many regions that are short of fresh water supplies. The policy of water management is therefore changing from being supply driven to demand driven. In a demand driven situation the price of water will increase and it is possible that even extensive treatment of wastewater may turn out to be cost effective in order to produce the necessary amount of freshwater. There are many possibilities for reuse of reclaimed wastewater, such as 1) for agricultural and landscape irrigation, 2) for urban reuse, 3) for industrial reuse and 4) for potable water supply. The different uses require different degrees of purity of the water, and water quality standards for this has been established (WHO, 1973, 1989). Today there are treatment technologies available that can produce reclaimed water from wastewater for these applications (Mujeriego and Asano, 1999). The greatest challenges in the reuse of reclaimed wastewater are: 1) the safeguarding of the hygienic quality, 2) the prevention of soil contamination and 3) the prevention of ground water contamination. Reclaimed wastewater for agricultural and landscape irrigation In most countries the greatest demand for water is for agricultural and urban irrigation. The wastewater resource to be utilised is firstly the water as such and secondly the nutrients in the wastewater. Wastewater purification at “sewage farms” was an example of zero discharge based on the “assimilative” and “self-purification” power of soil (Bouwer, 1993). Even though there are a few remaining of these “sewage farms”, the vast area required close to the city as well as health regulations, has made them disappear. After WHO in 1973 proposed unrealistically stringent guidelines for the quality of the effluent to irrigate crops, WHO issued in 1989 new guidelines for aqua-culture and non-potable urban uses. This new set of guidelines is controversial but has allowed a real development of wastewater reuse for irrigation purposes (WHO, 1973, 1989). Reclaimed wastewater for urban reuse Urban reuse can primarily be divided in two: 1. Reuse of reclaimed wastewater for toilet flushing in dual distribution systems 2. Reuse of reclaimed wastewater for recreational lakes and brooks as well as for creation of wetlands and wildlife habitat Dual distribution systems segregate the potable water supply from the non-potable system. Dual distribution systems can be developed in two ways. One approach is to construct a city-wide system in which the wastewater is returned to a central wastewater treatment plant for processing before being redistributed to the population to be used in the non-potable water supply system. The other approach is using small-scale individual systems where “grey” water, the wastewater from washing operations (sinks, bathtubs, showers, wash machines) and other non-faecal wastewater is treated
and redistributed to the non-potable water supply system. The latter of the systems have been more extensively used that the first one, caused by the fact that it can be implemented without interfering with the public city water and wastewater system. It is especially used in high-rise buildings, hotels, resorts etc The environmental movement has more and more focused on restoring natural environments within cities by establishing or restoring brooks and lakes as well establishing the basis for wetlands and wildlife habitats. For this purpose, reclaimed wastewater (or run-off water)is being extensively more used Reclaimed wastewater for industrial reuse Internal water recycling has been implemented successfully in several industries, while use of reclaimed municipal wastewater is less common. Because of the large volume, reclaimed wastewater can be particularly suitable for cooling-system make-up water, boiler feed water process waters for various production industries (i.e. iron and steel, textile etc)and wash-down waters(car wash etc). While requirements for irrigation applications tend to vary seasonally industrial water needs are more consistent. This makes reclaimed wastewater for industrial reuse easier to plan for Reclaimed wastewater for potable water supply Planned direct potable reuse of reclaimed wastewater is seldom used. The most well known is the operation in Windhoek, Namibia( Harhoff and van der Merwe, 1996). This fact is not caused by inability to produce potable water from wastewater or even to the cost of this, but rather by the public acceptance or, more accurately, public rejection of reclaimed wastewater as a potable water supply. The fact that people do not seem to object to reclaimed water from polluted rivers that carries water in which a very substantial fraction originates from sewage, is probably a matter of not knowing"(as long as I do not know, it does not matter) Much more common is planned indirect potable reuse in which treated wastewater is discharged to the groundwater, recharging this before used as a potable water source. The purpose of groundwater include: 1)arresting the decline of groundwater levels due to excessive groundwater withdrawals 2) protection of coastal aquifers against salt water intrusion from the ocean, and 3)to store the surface water(including reclaimed wastewater)for future use(Asano, 1998) RECLAMATION OF RESOURCES IN THE SLUDGE The wastewater sludge contains many different components, both valuable resources such organic matter, nutrients and metals(i.e. residual coagulants), as well as problematic components such as heavy metals and bacteria, virus's etc. The valuable resources in sludge may be reclaimed/reused in three ways 1. by direct use of sludge on farmland as fertiliser/soil conditioner 2. By use of a constructed soil conditioner(bio-soil) 3. By use of reclaiming resources(energy, nutrients, metals, etc) from the sludge through treatment Wastewater sludge may turn out to be a very valuable phosphorous source for producing P-fertiliser in the future. In 1989, the Phosphorous Resources Institute of Japan estimated that the phosphate rock in the world would remain for only 50 years at the use of the resources as at that time Watanabe et al, 2000)
5 and redistributed to the non-potable water supply system. The latter of the systems have been more extensively used that the first one, caused by the fact that it can be implemented without interfering with the public city water and wastewater system. It is especially used in high-rise buildings, hotels, resorts etc. The environmental movement has more and more focused on restoring natural environments within cities by establishing or restoring brooks and lakes as well establishing the basis for wetlands and wildlife habitats. For this purpose, reclaimed wastewater (or run-off water) is being extensively more used. Reclaimed wastewater for industrial reuse Internal water recycling has been implemented successfully in several industries, while use of reclaimed municipal wastewater is less common. Because of the large volume, reclaimed wastewater can be particularly suitable for cooling-system make-up water, boiler feed water, process waters for various production industries (i.e. iron and steel, textile etc) and wash-down waters (car wash etc). While requirements for irrigation applications tend to vary seasonally, industrial water needs are more consistent. This makes reclaimed wastewater for industrial reuse easier to plan for. Reclaimed wastewater for potable water supply Planned direct potable reuse of reclaimed wastewater is seldom used. The most well known is the operation in Windhoek, Namibia (Harhoff and van der Merwe, 1996). This fact is not caused by inability to produce potable water from wastewater or even to the cost of this, but rather by the public acceptance or, more accurately, public rejection of reclaimed wastewater as a potable water supply. The fact that people do not seem to object to reclaimed water from polluted rivers that carries water in which a very substantial fraction originates from sewage, is probably a matter of “not knowing” (as long as I do not know, it does not matter). Much more common is planned indirect potable reuse in which treated wastewater is discharged to the groundwater, recharging this before used as a potable water source. The purpose of groundwater include: 1) arresting the decline of groundwater levels due to excessive groundwater withdrawals, 2) protection of coastal aquifers against salt water intrusion from the ocean, and 3) to store the surface water (including reclaimed wastewater) for future use (Asano, 1998). RECLAMATION OF RESOURCES IN THE SLUDGE The wastewater sludge contains many different components, both valuable resources such as organic matter, nutrients and metals (i.e. residual coagulants), as well as problematic components such as heavy metals and bacteria, virus’s etc. The valuable resources in sludge may be reclaimed/reused in three ways: 1. By direct use of sludge on farmland as fertiliser/soil conditioner 2. By use of a constructed soil conditioner (bio-soil) 3. By use of reclaiming resources (energy, nutrients, metals, etc) from the sludge through treatment Wastewater sludge may turn out to be a very valuable phosphorous source for producing P-fertiliser in the future. In 1989, the Phosphorous Resources Institute of Japan estimated that the phosphate rock in the world would remain for only 50 years at the use of the resources as at that time (Watanabe et al, 2000)