Introduction: Modern Environmental problems
In recent years, environmental issues have become the main problem of human society. The industrial and technological revolution has brought tremendous changes in standards of living and the availability of free knowledge to people everywhere. Still, at the same time, it has created numerous new problems that are more difficult to solve and may even endanger the very existence of humans on earth.
The fast changes we are going through create an unbalanced environment as a result of the over-use of natural resources, destruction of buffering ecological systems, and production of waste in different phases: solid, liquid, and gas. Part of the effects of these processes is air pollution, global warming, soil contamination, freshwater reservoir destruction, and fatal damage to populations of fauna, flora, and humans.
In addition, the escalation in life standards leads to the rapid development of gigantic urban and industrial zones and the creation of substantial local pollution impacts within relatively small areas. This leads to a more unbalanced system without natural or technological buffering components.
Conventional technological purification solutions, even when available, can solve one problem at a time, usually causing other problems that are much more difficult to solve, such as air pollution, contaminated sludge, noise, etc.
Environmental problems in Urban Centers
The Urban environment has a dramatic effect on local resources and on the natural environment: a large concentration of humans and their activities in a relatively small area typically cause an increase in local pollution, a decrease in natural habitat, and more. Beyond these evident and observable effects, urban centers also act as ” heat sinks” or “hotspots” due to the tendency of materials such as concrete and asphalt to absorb heat. This creates micro-climates that induce more energy use (A/C), increasing non-renewable energy and air pollution.
Wastewater as a central problem in the urban area limits
Growing population and rising lifestyle standards accompanied by higher use of fresh water dramatically increase the volume of wastewater to be treated. More significant volumes, together with a larger number of sewage sources, requires highly developed piping systems, pumping stations, a great deal of energy, and highly expensive maintenance. Recent studies show that water & wastewater consumption and purification can consume one-third(!) of the energy used in large urban centers altogether.
Stormwater is a problem on its own in paved surface urban areas. Untreated storm water may become a potential polluting element after flushing numerous pollutants off the paved areas. In newly developed cities and urban areas, completely separating stormwater from sewage is standard practice. In existing cities, typically, there is no separate collection system; this situation often causes a lot of problems, especially after extreme rain events; Piping systems that cannot cope with the high momentary volume and sewage treatment systems collapse under the big loads. NYC is a perfect and severe example of such a situation.
In developing countries, the situation is often even worse: Urban centers in these locations usually need a collection system.
Water and wastewater management policy in developed countries
In recent years, following growing awareness of the complex and accumulative effects of urban centers, many local and national governments have put into practice policies, regulations, and recommendations. These are designed to promote the implementation of a wide array of practices for the conservation, purification, and protection of water resources and energy conservation and to increase the quality of living of city-dwellers:
- Water harvesting and storm-water buffering are now becoming standard practices in many modern developments as water management measures, reducing the loads on collection systems and providing re-charge of groundwater.
- There is a growing trend of increasing green spaces within urban centers for recreational and aesthetic purposes and air purification, storm-water buffering, and carbon sequestration. This trend has translated into national and international recommendations and standards: the World Health Organization (WHO) suggests ensuring at least a minimum availability of 9 m 2 of green open space per city dweller, while a standard of 40 m² urban green spaces and up to 140 m² per capita in high-quality suburbs has been suggested and, in some cases, implemented by experts around the world, mainly in Europe, North America and few developing countries.
These trends are indeed a positive step towards a more balanced environment. However, they, yet, need to address the main issues the cities face, such as heat accumulation, wastewater collection, purification, and reuse.
To deal with the water and wastewater of urban centers, the most pervasive governmental policy is that of Centralized Treatment. This requires collecting all wastewater and stormwater from the entire city and treatment in one or a few treatment facilities, typically outside the city or in industrial zones. Currently, many growing urban centers, particularly in the developing world, still need to have collection and treatment infrastructure. Installation of such systems, when possible, is not only highly costly but very disruptive to everyday life. In developed countries, often the situation is no better: many, if not most, of urban centers in the developed world, are now dealing with inadequate or dated infrastructure that cannot cope with the growing loads or has been damaged over time and requires replacement.
An integral part of modern urban planning and construction, urban landscaping provides an array of functions for the residents and visitors in the form of urban parks, gardens, boulevards, etc. These serve as recreational and aesthetic sites, help to define and differentiate between functional zones, are used for the commemoration of events or figures, and generally create a healthy environment. However, with the proper planning, Urban Landscaping can turn into an active tool that can also provide valuable ecosystem services to buffer the harmful effects of the urban environment and, in the long run, offer a substantial reduction in some operational costs associated with the continuous operation and improvement of the city infrastructure.
Some of the services active landscapes can offer:
- “Green Lungs” – carbon sequestration and removal of atmospheric pollutants
- “Green kidneys” – for wastewater treatment and recycling
- Mitigation of urban heat island effects
- Microclimate regulation
- Groundwater recharge
- Conservation of biodiversity
- Oxygen generation
- Noise reduction
- Reduction of freshwater consumption
- Prevention of soil erosion
- Life quality for generations to come
Natural Biological Systems (NBS), a practical, economical, and sustainable treatment system for water, soil, and air, offers sustainable, on-site solutions for integrating purification zones into densely populated urban centers and creating
Active Parks, reducing the need for complex infrastructure and expensive O&M.
Developed by the Israel-based Ayala Water &Ecology, the NBS is a modular and sophisticated nature-based tool enhanced by modern engineering. The NBS makes use of local biotic and abiotic components such as
- Varying Hydrology methods
- Plant database to match micro-organisms needed to dismantle pollutant sources
- Variety of aggregates, differing physically and chemically
Together, the biological, physiological, and chemical elements degrade, accumulate, extract, and volatilize contaminants of all kinds and offer a complete solution for a wide range of applications: Agricultural wastewater, Industrial wastewater, Landfill leachate, Sanitary & Urban Sewage, River and Lake Rehabilitation and more.
The NBS is constructed using local materials and labor and requires zero energy and negligible maintenance.
Over the past two decades, Ayala Water & Ecology has planned and executed many projects in the NBS method. These projects were executed in the urban, industrial, and agricultural zones and were typically designed as part of the landscaping plan.
Some of these are:
1. Purification and upgrade of contaminated stream water: The system upgrades low-quality water flowing through the heart of an urban center. The system is designed as a by-pass: part of the stream water passes through the system and is returned to the stream after purification or is used for irrigation if required. The system is part of the landscape design of an existing park on the riverbank (see figure 1) in the heart of the dense urban center.
2. Wastewater purification in the center of a commercial urban zone: In this case, the system purifies local domestic sewage. After purification, the water is used for irrigation or is discharged to a nearby stream. The system is designed as an attractive landscape element ( see figure 2)
3. Large urban system for treatment of an entire neighborhood in dense urban settings: This system combines purification ponds with ornamental ponds, and a sub-surface irrigation system stretched over the entire neighborhood landscape (see fig 3)
4. Purification and re-use of industrial wastewater in a cosmetic factory: the system was designed as part of the environmental planning; the treated wastewater is used for irrigation and developing a unique landscaping area nearby
(see fig 4).
5. Purification system for treatment of landfill leachate in the urban zone: The system treats the landfill leachate and garbage trucks cleaning water to a high quality that allows unlimited irrigation of the parameter (see figure 5).
6. Complete planning for the city of Nice and the Var valley (Cote D’Azure): for ecological, sustainable solutions to solve local problems such as flooding, aquifer depletion and contamination, air pollution, and disappearance of local flora and fauna. The city of Nice has been suffering for many years from flooding during the rainy season, which causes a great deal of damage. In addition, the urban and industrial growth in the region has caused continuous and worsening damage to the quality and quantity of the local aquifer. The complete plan Ayala provided included ecologically sustainable solutions integrated into the urban, industrial and rural zones, using natural and local elements and holistic restoration techniques
7. Future planning approach: India is currently one of the countries with the highest rate of demographic and urban changes on earth. The high rate of change, coupled with the need for prior infrastructure, requires innovative and creative solutions for environmental problems. Mumbai, for example, is going through an
immense development process, with the limiting factors being mainly transportation and wastewater.
Conventional, high-energy solutions cannot adequately answer the existing situation and future requirements.
Implementation of the Active Landscape planning approach using the NBS technology will provide an economical, sustainable, and highly efficient solution for many years to come, one that will contribute to high- quality water, enrichment of the depleting aquifer, reduction in air pollution, reduction in urban energy usage
and other costs associated with wastewater treatment, and a general increase in the quality of life in the urban center.
Combining this unique approach with a variety of sustainable eco-management techniques, allows us to focus not only on a localized solution but also on an entire city, watershed, or ecosystem and to create solutions that promote groundwater recharge, flood prevention, restoration of local flora and fauna and reduction of energy use.