Wastewater treatment and effluent reuse

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Wastewater Treatment

and Effluent Reuse

MEKOROT WATER IS A BUSINESS FOR LEADERS

Mekorot, Israel National Water Company, Public Relations Unit, 9 Lincoln st Tel Aviv 61201, ISRAEL

Tel: 972-3-6230705, Fax: 972-3-6230641, Website: www.mekorot.co.il

Initiated and Produced: Public Relations Unit

-Head Office

Professional Contents: Dan Region Unit - Central District

Waste Water Treatment and Reuse Division - Head Office

Districts' Process Engineers

Copywriter: Zohar Lidovsky

Translation: SET Group

Graphic Design and Production: Trigon Design

Photographers: Albatros, Moshe Barkon, Eli Dgani, Israel

Sun, David Tzadok, Moshe Shai

May 2006

The company invests a lot of efforts and capital in research

and development of related areas such as effluent desalination,

treatment by membranes and development of alternative

methods for chlorine disinfection, in cooperation with leading

Effluent Reuse Project - Ayalon-Latrun

companies throughout the world

One of Mekorot's main goals for the coming decade is to utilize all the effluent in Israel, thereby to stop the disposal of 110 million cu.m./Year of effluent to the environment

Introduction

Since its establishment the State of Israel has

been confronting water shortage due to the dry

climate, the desert expanse and the scarse water

sources

Mekorot, the national water company, has been

constantly searching for solutions in order to

increase the water supply, whether by improving

the utilization of the existing sources or by finding

additional ones

Within the framework of its activities, the

company deals with wastewater treatment and

effluent reuse for agricultural purposes Mekorot

considers the improvement of the wastewater

treatment level and the expansion of the uses of reclaimed water as most important professional and ecological challenges The replacement of fresh water with reclaimed effluent for agricultural irrigation permits the supply of additional drinking water to the population, while maintaining environmental quality by reducing the ecological damages caused by wastewater

Mekorot is responsible for 40% of the treated wastewater in Israel and for more than 50% of effluent reuse for agricultural needs in the country The quantities and quality of the reclaimed effluent are among the highest in the world

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What are the stages of wastewater

treatment?

rags, stones and plastics are removed This stage also

includes coarse filtration by bar screens and removal of sand

and oils in grit chambers

the load on the biological treatment (the secondary),

which consumes great amounts of energy During the primary

treatment, approximately 30%-35% of the organic materials and

40% to 60% of the suspended solids are removed by gravitational

sedimentation

the dissolved organic materials in the wastewater This

process takes place by utilizing bacteria and microorganisms

that digest the waste products, while introducing oxygen into

the liquid by mechanical means (aerators or air difussion) In

order to remove the contaminants from the wastewater, the

bacteria population is multiplied to the extent that there are

enough bacteria to digest the contaminants within a given time

The organic matter found in the wastewater and the oxygen

supplied are requisites for these aerobic bacteria’s existence

During the digestive process the bacteria develop into larger

colonies, which can be separated from the fluid using secondary

sedimentation After sedimentation high-quality effluent result,

suitable for agricultural use in accordance with the Ministry of

Health regulations

What is the principle of wastewater treatment?

Wastewater treatment in Mekorot's facilities is based on the principle according

to which very high concentrations of the microorganisms meet with high-load wastewater, under a massive supply of oxygen (aerobic conditions) This process significantly shortens the natural treatment duration that takes place in the streams

- from weeks and months to less than 24 hours!

removal of contaminants, suspended matter, bacterial and other microorganisms found in the secondary effluent This is done by filtering the effluent through a deep granular (sand) bed filtration and disinfection by the addition of chlorine or other disinfectants At the completion of the treatment, the result is very high-quality effluent, sent to the reclamation systems for unlimited agricultural use, or to streams

What are the wastewater treatment methods?

method was the cheapest and most used According to this method, wastewater is sent to shallow ponds for several weeks, until alga grows and multiplies The alga releases large quantities of oxygen during photosynthesis, utilized by the bacteria to remove the organic materials in the wastewater

determined on "20/30 regulations", according to which each municipality is obligated to treat its wastewater in order

to obtain effluent quality of no more then 20 mg/l BOD and no more than 30 mg/l suspended solids) As a result, many facilities (Wastewater Treatment Plants - S.T.P) have adopted this mechanical-biological method, that was found more advanced and efficient than the Oxidation Ponds By this method, a dense population of microorganisms is maintained in a constant state of mixture/circulation in the reactors to which the raw wastewater

Yavne recharge fields Effluent Reuse Project - Ayalon-Latrun Ashkelon S.T.P

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Wastewater Treatment

is introduced The microorganisms digest the organic material

and the nitrogen and phosphorus compounds, and utilize the

oxygen supplied In this form the microorganisms multiply their

number at a very rapid rate, so that the process continues for

12-18 hours only After their stay in the reactors, the multiplying

bacteria (biological sludge) are separated from the effluent in

sedimentation clarifiers

includes a thickning system for the sludge, before entering

into the digesters In the digesters, which are generally anaerobic, the bacterial digestion process takes place, without oxygen, and at a temperature of 35°-37°C The sludge is transferred

to dewatering facilities for water extraction and the sludge (with 20%-25% solids content) can be disposed of in containers for agricultural use The gas produced in the digesters, mostly methane, can be utilized to generate electricity with a bio-generator The residual heat of this process is used to heat the sludge in the digesters

Ashkelon S.T.P

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Wastewater Treatment by Mekorot

Mekorot treats approximately 40% of the wastewater treated in Israel every year In 2005 the company operated

8 purification plants around the country

Equivalent Value

Daily flow (M3) Annual flow

(millions of M3)

Total 3,005,000 502,000 185.9

Effluent Reclamation by Mekorot

Mekorot aspires to return all of Israel’s effluent to agriculture, thereby to contribute to the water resources in the country At present, Mekorot returns over 50% of the reclaimed effluent to agriculture through 9 reclamation plants which are among the largest and most advanced in Israel:

Plant Connected Wastewater Facilities

Annual Consumption (millions of M3)

The Third Line to the Negev Dan Region Association of Towns

(D.R.A.T)

145

¥

£

Facts & Figures

Drinking water consumption in the urban and industrial sectors in Israel is 800 million cu.m per year (Data from year 2005).

470 million cu m of wastewater are created every year in Israel

430 million cu.m of wastewater are treated every year (about 90%)

340 million cu.m of effluent (treated wastewater) are reused every year for agriculture (about 70%)

110 million cu.m of non-reused effluent are returned to the environment (about 26%)

£

Karmiel S.T.P

µ

The Shafdan - the Dan Region Wastewater Treatment Plant - is owned by the Dan Region Association of Towns (D.R.A.T), which includes seven municipalities and many other settlements

The facility Is one of the largest and complex plants in Israel, and is considered to be the largest and most advanced of its type in the Middle East The Shafdan treats about 130 million cubic meters of wastewater annually, and returns the reclaimed water to the Negev through “The Third Line to the Negev” reclamation system The facility serves a population of about 2 millions of people, in the most crowded and densely populated area in the country - the Dan Region

Mekorot is responsibe for the operation of the facility, guarantees the desired quality level of the

effluent; recharges them to confined aquiter through infiltration fields in order to improve their quality, pumps the reclaimed water through recovery wells and supply them to the Negev at a quality permitting unlimited agricultural crop irrigation

In this way Mekorot provides a solution for Israel’s increasing water needs, by turning more fresh water to urban use.

The fruitful cooperation that has lasted for many decades between the two public organizations: The Dan Region Association of Towns and Mekorot, has guaranteed and will guarantee in the future efficient wastewater treatment and reuse, at a very high professional level.

∂

Shafdan

Effluent Recharge and recovery

After the biological treatment (secondary stage) in the Shafdan

plant, the effluent are sent to infiltration fields in the sands of

Rishon Le-Zion and Yavneh, where they are recharged into the

aquifer (ground water reservoir) by alternate regime of flooding

and drying As it seeps through the ground, the water undergoes

physical, biological and chemical processes that improve their

quality In addition, the underground stay serves as a seasonal

and multi-annual storage for large quantities of water, that are

used for irrigation during “dry” periods After the transfer to

the aquifer, and during the stay and flow there, the water is

pumped by about 150 recovery wells Their purpose is to pump

the reclaimed water and prevent it from penetrating into other

wells in the area, which are used for drinking water supply The

quality of the reclaimed water is very high, suitable for unlimited

irrigation

The “Third Line to the Negev” enterprise consists of a combined

system of pipes, resevoirs and pumping stations whose purpose

is to improve the quality of the Shafdan effluent and transfer

it for agricultural use to the Negev The reclaimed water are

suitable for unlimited irrigation, without fear for the customer’s

health

The third pipeline is separated from the two other pipelines that

supply drinking water to the Negev (the eastern “Yarkon-Negev”

and the western “Yarkon-Negev” pipelines), and is intended to

transfer only reclaimed water for unlimited irrigation for all types

of crops in the Negev

The system is made up of three main pipe sections, whose total

length is 90 kilometers, six operational “floating” reservoirs and

three end reservoirs in the Negev, in order to collect the stored

reclaimed water during the winter and increase the quantity of

water supplied for irrigation during the summer months

“The Third Line to the Negev”

By returning reclaimed water to the Negev, Mekorot has achieved the following goals:

Full utilization of Shafdan effluent and prevention of wasting one of the most precious resources

in Israel – water

Improvement of the water balance in Israel by diversion of a larger quantity of fresh water for domestic and industrial use

Transferring large agricultural areas from the congested center of the country to the expanses of the Negev

Creation of green groves and fertile agricultural fields in previously arid and desolate areas Reduction of the potential contamination of ground water and the spreading of disease to the population due to lack of appropriate wastewater treatment and disposal

Goals

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Initiated and Produced: Public Relations Unit

-Head Office

Professional Contents: Dan Region Unit - Central District

Waste Water Treatment and Reuse Division - Head Office

Districts' Process Engineers

Copywriter: Zohar Lidovsky

Translation: SET Group

Graphic Design and Production: Trigon Design

Photographers: Albatros, Moshe Barkon, Eli Dgani, Israel

Sun, David Tzadok, Moshe Shai

May 2006

Wastewater Treatment

and Effluent Reuse

MEKOROT WATER IS A BUSINESS FOR LEADERS

Mekorot, Israel National Water Company, Public Relations Unit, 9 Lincoln st Tel Aviv 61201, ISRAEL

Tel: 972-3-6230705, Fax: 972-3-6230641, Website: www.mekorot.co.il