Gray water treatment with advanced technologies, your kind hints ?

Rafik Karaman

Dear Saifeldin,

The following publications cover the answer to your question:

1-Greywater Recycling and Reuse

What is greywater?

Greywater is all wastewater that is discharged from a house, excluding blackwater

(toilet water). This includes water from showers, bathtubs, sinks, kitchen,

dishwashers, laundry tubs, and washing machines (Figure 1). It commonly contains

soap, shampoo, toothpaste, food scraps, cooking oils, detergents and hair.

Greywater makes up the largest proportion of the total wastewater flow from

households in terms of volume. Typically, 50-80% of the household wastewater is

greywater. If a composting toilet is also used, then 100% of the household

wastewater is greywater.

Not all greywater is equally "grey". Kitchen sink water laden with food solids and

laundry water that has been used to wash diapers are more heavily contaminated

than greywater from showers and bathroom sinks. Therefore, different greywater

flows may require different treatment methods that would render the water suitable

for reuse.

http://www.fbr.de/fileadmin/user_upload/files/Englische_Seite/Greywater_Recycling_Introduction.pdf

2- Another type of recycled water is "gray water".Gray water, or gray water, is reusable wastewater from residential, commercial and industrial bathroom sinks, bath tub shower drains, and clothes washing equipment drains. Gray water is reused onsite, typically for landscape irrigation. Use of non toxic and low-sodium (no added sodium or substances that are naturally high in sodium) soap and personal care products is required to protect vegetation when reusing gray water for irrigation. National Science Foundation (NSF) International has established a wastewater treatment task group on onsite residential and commercial gray water treatment systems. They have developed a draft new standard – NSF 350 – Onsite Residential and Commercial Reuse Treatment Systems. This standard encompasses residential wastewater treatment systems (similar to the scope of VSF/ANSI Standards 40 and 245) along with systems that treat only the gray water portion. For more information visit the NSF website . EPA and CDC brought together agency and academic experts to explore the science available for addressing high-priority regional needs in the areas of:

Gray water exposure risk to humans and ecosystems;

risk management options for gray water;

water scarcity,

and trends in water use.

For more information visit EPA's Regional Science Workshop website.

Through the natural water cycle, the earth has recycled and reused water for millions of years. Water recycling, though, generally refers to projects that use technology to speed up these natural processes. Water recycling is often characterized as "unplanned" or "planned." A common example ofunplanned water recycling occurs when cities draw their water supplies from rivers, such as the Colorado River and the Mississippi River, that receive wastewater discharges upstream from those cities. Water from these rivers has been reused, treated, and piped into the water supply a number of times before the last downstream user withdraws the water.Planned projects are those that are developed with the goal of beneficially reusing a recycled water supply.

How Can Recycled Water Benefit Us?

Recycled water can satisfy most water demands, as long as it is adequately treated to ensure water quality appropriate for the use. The Treatment and Uses chart shows types of treatment processes and suggested uses at each level of treatment. In uses where there is a greater chance of human exposure to the water, more treatment is required. As for any water source that is not properly treated, health problems could arise from drinking or being exposed to recycled water if it contains disease-causing organisms or other contaminants.

https://www3.epa.gov/region9/water/recycling/

3- New Approaches and Technologies for Wastewater Management

Author: Glen T. Daigger

Integrated closed-loop systems for recycling water and waste material can meet consumer demands and satisfy environmental imperatives.

In the past decade, practical applications of a variety of new wastewater-treatment technologies, such as membrane filtration systems and advanced oxidation, have led to new ways of managing urban water systems and water resources (Daigger, 2003). These new treatment regimes, especially the integration of urban-water and waste-management systems, promise to dramatically improve the sustainability of our water resources.

These new systems are creating new needs, which are driving further technology development. In this paper, I discuss the circumstances that have necessitated change in urban water and resource management; describe some of the changes that are already being implemented; and describe technological advances that are under development.

The Need for Change

The major driver of change is, quite simply, population growth coupled with a rising global standard of living, a combination that has resulted in resource consumption (including water use) that exceeds the current resources of planet Earth (Daigger, 2007b, 2008a; Wallace, 2005). Let’s say the current population of slightly more than 6 billion consumes the resources of one planet Earth. By about 2050, when the population is expected to reach about 9 billion, and if standards of living continue to rise, the amount consumed will be the resources of about three planet Earths. Obviously, this scenario is not sustainable.

When the population of Earth was much smaller (e.g., fewer than 2 billion) and when per capita use of resources was much smaller, our traditional “take, make, waste” pattern of resource consumption was sustainable. Now, however, we need to recycle and reuse all types of resources (including water), and we must increase our use of renewable resources.

Water Stress

In contrast to many other natural resources, water is inherently renewable. Mother Nature has been recycling water since the origin of life on the planet. When the rate of net abstraction and use of water prior to its being returned to the environment exceeds the natural rate of recycling, water stress develops. Water-management practices can add to water stress by reducing the amount of water available, for example by returning water to the environment in a polluted state or by altering land configurations in ways that adversely affect natural water-restoration processes, such as those provided by wetlands.

Water stress currently affects only a modest fraction of the human population, but it is expected to affect 45 percent of the population by 2025 (Daigger, 2007b; WRI, 1996). This situation will be further exacerbated by global climate change, which is altering water-supply and storage patterns in ways that make existing water-management infrastructure less effective.

Recycling technologies can significantly reduce net water abstraction from the environment, but many of those technologies require an increase in the consumption of other resources, especially energy. In our resource-constrained world, increasing the consumption of any resource, even for necessary functions such as water management, must be carefully considered.

A further aspect of water stress caused by urban water-management systems is the increase in the amount of nutrients, especially phosphorus, in the aquatic environment (Steen, 1998; Wilsenach et al., 2003). Mined as phosphate rock, phosphorus is used to manufacture fertilizer, which in turn is used to grow crops that are subsequently consumed by humans. Phosphorus (and other nutrients) then pass through us as we metabolize food and end up in the wastewater stream. When these effluents are discharged to the aquatic environment, the excess nutrients can cause eutrophication. At the current rate of consumption, the supply of phosphate, an essential nutrient with no known replacement, is expected to be exhausted in about 100 years. Thus, there are at least two urgent reasons for us to recover phosphate from the wastewater stream.

Two other factors must be taken into consideration. First, although water service is uniformly provided in the developed world, approximately 1 billion of the people on Earth do not have access to safe drinking water, and more than 2.5 billion do not have access to adequate sanitation. Clearly, we need more efficient urban water management to meet global needs. Second, water and wastewater utilities around the world are hard pressed to find sufficient funding to maintain, let alone extend, their infrastructure to meet growing needs.

https://www.nae.edu/Publications/Bridge/V38N2/NewApproachesandTechnologiesforWastewaterManagement.aspx

GREY WATER RECYCLING

Sandeep Thakur*1

, M.S. Chauhan 2

*1 Research Scholar, Department of Civil Engineering, Maulana Azad National Institute of Technology Bhopal, India-462051.

Email: [email protected]

2 Professor, Department of Civil Engineering, Maulana Azad National Institute of Technology Bhopal, India-462051.

Email: [email protected]

Abstract— Water is one resource that has no substitute. Even though water covers three quarters of the planet, 97% of the Earth's water is saline water, and thus useless for drinking and other purposes. Less than 3% of water is fresh water. In the recent years, many events have occurred which point towards the decreasing fresh water resources of the world. As the needs for water increase in agriculture, industry and households with the increase in cities and populations the problem is getting worse globally. This situation necessitates that the need of conservation of

water be understood and put into practice. Therefore it is essential to reduce surface and ground water use in all sectors of uses and to substitute fresh water with alternative and to use water efficiently through reuse options. Rainwater and greywater are good alternative resources. Rainwater Harvesting is one of the most

useful options of water conservation but it has some limitations such as it is only useful in the area where rainfall occurs. Greywater recycling is the viable option that can be very useful in the water arid areas. The aim of the study is to implement a grey water-recycling scheme at Household level. Since the intended use

of water is for irrigation and toilet flushing, the required treatment standards are therefore less stringent as compared to that for drinking purposes. The treatment methods would nevertheless depend on the quality of grey water.

http://jessresearch.com/wp-content/uploads/2013/12/v1-i4-p4.pdf

4- Journal of King Saud University - Engineering Sciences

Volume 25, Issue 2, July 2013, Pages 89–95

Open Access

Original Article

Studying the efficiency of grey water treatment by using rotating biological contactors system

Amr M. Abdel-Kader,

doi:10.1016/j.jksues.2012.05.003

Get rights and content

Open Access funded by King Saud University

Under a Creative Commons license

Abstract

The need for water is growing with increasing population and the adverse impacts of climate change especially in the Mediterranean basin. Innovative concepts and technologies are urgently needed to close the loop for water. Among the options for innovative water resources, segregation of grey water and reuse is receiving crucial attention for decentralized areas as a sustainable approach. Grey water represents substantial portion of household water consumption in volume. Treated grey water to a level complying reuse rules and regulations can be reused for several purposes including agriculture, landscaping and toilet flush. The mathematical model was used to investigate the performance and treatment capability of Rotating Biological Contactors (RBC) to treat the grey water. The GPS-X (version 5.0) simulation program was used in this study to simulate the proposed RBC plant. The proposed Rotating Biological Contactors (RBC) plant is composed of three parts, first is the RBC tank unit, second is the settling tank unit and third is the disinfection tank unit. After the model optimization, three different concentrations of the grey water were used to run the proposed mathematical model. Low, medium and high concentrations of the grey water were used to run the model. The proposed model was verified by using data from RBC experimental pilot plant. The results of this study showed that, the treatment efficiency of the RBC system based on BOD removal was ranged between about 93.0% and 96.0%, and based on TSS removal was ranged between about 84.0% and 95.0 % for all concentrations of influent grey water. Also, the proposed model results indicated that grey water can be properly treated by RBC system and can be reused for many purposes after disinfection and sand filtration.

http://www.sciencedirect.com/science/article/pii/S101836391200013X

5- California is facing a serious drought that prompted Governor Arnold Schwarzenegger to declare “This drought is having a devastating impact on our people, our communities, our economy and our environment…This is a crisis, just as severe as an earthquake or raging wildfire, and we must treat it with the same urgency by upgrading California's water infrastructure to ensure a clean and reliable water supply for our growing state.” After three years of dry weather, and with forecasts of precipitation and snowpack below normal levels, California is preparing for the likelihood that 2010 will be a fourth year of drought [1, 2] with the State's key water reservoirs projected to be at only about 70% of their average storage. Unless precipitation leads to significant restoration of the State water supply and demand is reduced, the situation in California will become unsustainable.

WATER USE IN CALIFORNIA

The California Department of Water Resources has pursued a multifaceted approach to address the severe water shortage in California, with water conservation as a key element of its plan. Among its various elements, the approach considers reduction in water use efficiency and conservation, as well as the reclamation and reuse of municipal, industrial and agricultural wastewater streams. Various California local governments have already implemented and/or are encouraging water conservation measures, including water rationing and water reuse. The largest percentage of water consumption (77%) in California is attributed to agriculture (Figure 1) with an estimated 13% for urban residential use (both single- and multi-family). In Southern California (the South Coast Hydrologic Region), however, about 54% of the water consumption (Figure 2) is attributed to urban residential use, which accounts for the largest usage of potable water by the municipal and industrial (M&I) sector (i.e., the urban sector). Although use of water by the M&I sector in the South Coast Hydrologic Region represents a small fraction of California’s total water use (~6%), the loss of even a small percentage of this potable water apportionment can have significant impact on the quality of life in urban areas. For example, in order to cope with water shortages, the Los Angeles Department of Water and Power (LADWP) has implemented a program that includes restrictions on urban irrigation, guidelines for residential water conservation, and shortage-year water price increases.

http://www.environment.ucla.edu/reportcard/article4870.html

6-http://www.zapmeta.ws/ws?q=gray%20water%20filter%20system&asid=ws_gc3_10&mt=b&nw=g&de=c&ap=1o1

Hoping this will be helpful,

Rafik

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