ABSTRACTS

Conference report

Managing the Wastewater Resource - A summary of the Conference in Aas, Norway (June 7-11, 1999)

By: Bjørn Kløve, Jordforsk, Norwegian Centre for Soil and Environmental Research

The growing global interest in ecological engineering is reflected in the number of countries participating in the conference: about 200 people from 30 countries attended the conference. In Western Europe the driving forces for ecological wastewater treatment are government regulation and cost. More and more, states are increasing their requirements for purifying wastewater, especially in rural areas. In addition, there is a growing awareness that local treatment of wastewater is less expensive than traditional solutions in which pipelines transport the wastewater to large treatment units. Many examples show that small-scale local treatment, with soil infiltration or constructed wetlands, are both cost-effective and highly efficient for the removal of P, N, organic material and bacteria – even in cold climates. However, new techniques are needed where suitable soil is not available for infiltration.

The use of wastewater for aquaculture, irrigation and fertilizer has deep historical roots in Asia, especially in China and India. In both the East and West, innovative applications for wastewater are being tested. In Italy, for example, wastewater irrigates greenhouses; in Sweden it nurishes energy forests; and in the Netherlands and Germany it produces plankton for fish and poultry farms.

Separating wastewater from stormwater is an efficient method for exploiting wastewater nutrients. Separate systems also decrease the risk of overflow at sewer treatment plants during large rainfalls, which is a water quality problem in many countries. Another division principle is source separation in which black- and greywater are separated at the source (e.g. house). This technique uses nutrients from the greywater for, say irrigating local vegetation, and the partially purified water is reused for toilet flushing. Solids from blackwater can be efficiently collected with a vacuum toilet and composted with household organic waste from the kitchen and garden to produce energy. Experiences with a full scale pilot system in Germany have shown that the economical viability of these systems is closely connected to their size and to whether there already is an existing sewer network.

Source separation also reduces concentrations of heavy metals and organic pollutants in wastewater. Since urine contains 80 % of wastewater's nitrogen and 50 % of its phosphorus, urine holds promise to be a rich fertilizer for agricultural, horticultural and forestry purposes. However, urine is also a major source for microcontaminants such as antibiotics or hormones in the wastewater. Future research must take this into account.

Local treatment of wastewater must meet rigorous hygiene requirements because of the health and safety issues associated with contaminated well water. Some microorganism can survive in groundwater due to low temperatures and lack of UV-radiation. Empirical data show that bacteria can be transported several hundred meters if the flow occurs in macropores. Since problems related to the source and transport of pathogenic organisms are not well known, this topic will remain an important issue in the future. For example, a Swedish study shows that storm runoff can be the recipients' largest source of pathogenic bacteria. In many cases, storm water treatment is required for continued improvement of water quality.

The conference demonstrated the increasing demand for creative and imaginative methods to treat and use wastewater. A conference delegate summarized:

"A new approach to on-site wastewater management is emerging: Utilization instead of disposal. In this model, effluents are used on site - they'regrown away not thrown away."

However, this also means that it is getting more and more difficult to decide which one of these solutions suits best in terms of sustainability, economic viability and performance. There is a growing need for system planning tools for engineers. There is also a need for decision support tools for decision makers. Any future conference on ecological engineering must take this into account.

Annual course in Sweden

"Ecological alternatives in sanitation"

By our Swedish correspondents Anneli Carlander, Caroline Höglund and Björn Vinnerås

Most cities in the world are short of water and many are subject to critical environmental degradation. Their periurban areas are among the worst polluted and disease ridden habitats of the world. Sewage discharges from centralised water-borne collection systems pollute surface waters and seepage from sewers, septic tanks and pit latrines pollute groundwater. Urbanisation and general population growth increase the stress on natural resources.

Most cities cannot rely on further exploitation of virgin water sources. At the same time, more people have to be fed, and the need for fertilisers increase. Therefore, local groundwater needs to be protected and used water as well as nutrients from consumed food has to be treated and reused in order to obtain reasonable amounts of water and food. Major changes in urban water management are anticipated and will involve professional groups and authorities as well as households.

Ecological alternatives in sanitation have recently been given prominence on the development agenda and a number of projects, supported by SIDA, from no-mix toilets to the use of urine in urban agriculture. This multidisciplinary field concerns cultural and social desirability, hygienic risks, potential of reuse of nutrients from human excreta in agriculture, affordability, technical construction and promotional issues.

The program is conducted in English and the participants are professionals engaged in town planning, water supply, waste management and socio-economic development; researchers and trainers in fields of environmental sanitation and key persons engaged in NGOs with projects related to improved sanitation.

The course is given for the first time this year and will be given every year for five weeks during late July and August.

The objective is that participants through the programme will acquire information and knowledge about new options in sanitation in order to support urban dwellers in reducing environmental health risks, improving their nutritional status and protecting their nutritional status and protecting their water sources.

The course is given with pedagogy based on problem based learning (PBL) and except the participation in Stockholm water symposium the course is divided in four cases.

• The first case concerns water scarcity and how to get access to healthy water.
• Case number two is about hygienic quality and how to make the latrines safe.
• Case three is a more socio-economic case about how to get reliable information especially when investigating issues that can be found sensitive as for example toilet habits.
• Case number four gives more emphasis on how to reuse the nutrients found in the collected excreta; its fertiliser-value and in which amounts the nutrients should be expected.

During the course a lot of different geographical areas in Sweden are visited to give an idea about how different techniques can be implemented in the society and to see how it works in reality. The date for application is during late April.

To get application papers contact jandr@tema.liu.se

Conference report

Stockholm Water Symposium 1999

By our Swedish correspondents Anneli Carlander, Caroline Höglund and Björn Vinnerås

This year Professor James J. Morgan from USA held the Stockholm Water Prize Laureate Lecture with the title "Aquatic chemistry for protection of water ecosystems and human health". Approximately 700 participants from around 70 different countries attended the Symposium taking place in the centre of Stockholm during the same week as the Stockholm Water Festival.

According to the Final Program the 1999 Symposium had its focus on future strategies for urban water management through qualified and dialogue-based problem analysis, identification of potential solutions, and attention to implementation barriers that have to be overcome. It uses as a platform a 1996 UNESCO Symposium on "Integrated Water management in Urban Areas" and a number of workshops in earlier Stockholm Water Symposia. Its aim is to identify and formulate (based on a systems approach) criteria and strategies for urban planning and development, paying adequate attention to different perspectives, stakeholder groups, and the environmental preconditions as defined by the "water address" of the city.

All over the world people are moving to cities, expecting improved standards of living. This tendency puts extreme stress on water supply and sanitation authorities. Water supply and sanitation are key preconditions for stability. Water scarcity makes recycling and rainwater harvesting increasingly interesting as a city grows. Achieving safe sanitation for all by 2025 would demand providing almost half a million new inhabitants daily for 30 years. Realism in sanitary technique is therefore a fundamental challenge.

The first one and a half day was devoted to plenary sessions and the following one and a half to various workshops with the following topics:

1. Water reuse within the city
2. Mitigation of flood hazards in urban areas
3. Interaction between urban and peri-urban water-related activities
4. Water and social stability
5. Town planning and urban metabolism: integrating water-waste-energy management
6. Challenges to urban water management in developing countries
7. Urban areas as seen in the river basin context
8. Long-term water supply an sanitation solutions
9. Sustainable sanitation

During the workshops many case studies as well as more general issues were dealt with. As a presenter and participant of workshop 9 I can say that this workshop was very well held together with inputs from many parts of the world. Several participants of the course "Ecological Alternatives in Sanitation" were presenting.

A common feature of many of the alternative sanitation solutions tested and promoted in different countries was urine diversion. The urine and faeces are diverted already in the toilet and either fraction may be used in agriculture. Compared to the traditional pit latrines, which still are predominating in developing countries, groundwater contamination by sewage can be avoided, thus improving public health.

The last day of the Symposium was devoted to plenary sessions and the closing session, including distribution of a few more prices. During the whole Symposium there was also a posters session running. Both oral presentations and posters can be found in the Abstracts book compiled prepared before the Symposium. A full Proceedings will later be available.

E-mail: sympos@siwi.org

Report from a field trip

Field experiment at Stockholm on the fertilising value of source separated human urine

By our Swedish correspondents Anneli Carlander, Caroline Höglund and Björn Vinnerås

The project "Source separated human urine - a future source of nutrients for agriculture around Stockholm?" with the main sponsors being Stockholm Water Company, Stockholmshem and HSB (the two latter are housing companies) have been running for about four years and this is the third year of field experiments to compare the fertilising effect of human urine to the effect of mineral fertiliser. The experimental fields are situated south of Stockholm on the land owned by Stockholm Water Company close to their reserve water supply; Lake Malaren being the surface water supply normally used.

Human urine is a complete fertiliser with the composition of the macronutrients N:P:K being approximately 11:1:2.5. Furthermore urine contains several micronutrients and very low amounts of heavy metals. In 1997 the yield of the crop fertilised with urine was ~75% of the cropyield obtained with mineral fertiliser. But in 1998 the results were comparable, both for fertilisation before sowing and for fertilisation in growing crops, urine and mineral fertiliser yielded approximately the same amount of crop. The 1999 crop will soon be harvested and final results will be available sometime this winter.

Looking at the crop during the visit to the field, a trained eye seems to be needed to draw any conclusions. Despite the extremely dry and hot summer in the coastal east of Sweden the crop was judged to look fine and healthy. The summer of 1998 was the opposite; the rain was pouring down most days, so it will be interesting to see if there will be any difference. The nitrogen content of the urine was around 2 mg/l urine solution, that is urine + the flushwater used in the separating toilets and possibly also water from seepage through the pipes.

After the visit to the field Caroline Hoglund, a PhD-student at the Swedish Institute for Infectious Disease Control, talked about the hygienic aspects of the reuse of urine. Thereafter Dr Hakan Jonsson talked about environmental impacts, e.g. the decrease in eutrophication possible to achieve by introducing urine separation, or urine diversion which might be a more appropriate term since the two fractions excreted never are mixed.

Literature review from Canada

Recent developments in naturally-based wastewater treatment, recovery and reuse options

Source: Jackie Foo, Ecotechnology Announcements

The aim of the report is to review recent developments in naturally-based wastewater treatment, recovery and reuse options and to explore how alternative interventions could potentially contribute to the:

• i) provision of sanitation
• ii) conservation/protection of fresh water resources
• iii) improvement of soil integrity
• iv) production of value-added products through linkages with URBAN AGRICULTURE.

The report suggests that alternatives exist to highly capitalised and centralised biowaste treatment systems that are dependent on water-borne conveyance and electromechanical inputs for operation and maintenance.

The report explores the concept of managing urban wastewater flows at zero and intermediate distances, based on urban micro-watersheds, and reviews several technological interventions that may act as key components of integrated bio-systems (IBS). The report is divided into two major sections.

SECTION A is comprised of the problem background and reviews central themes associated with the management of bio-waste in an urban, developing world context. This section also suggests that zero-discharge systems are requisite to decreasing the environmental externals that accrue from community to city to ecosystem to biosphere when linear discharge options are favoured.

SECTION B reviews selected treatment and recovery technologies that were identified as noteworthy and potentially appropriate for treating and recovering bio-waste and facilitating its reuse at the local level.

Gregory Rose: http://www.fes.uwaterloo.ca/u/gdrose/
Report: http://www.idrc.ca/cfp/rep27_e.html