Three pilot plants / installations have been realised in the project:

Google Map Morocco, El Attaouia

some pictures of the HF-CW realisation in Sekem, Egypt, are available here

some pictures of the pilot site El Attaouia, Morocco, are available here

some pictures of the HF-VF-HF CW realisation in Chorfech, Tunisia, are available here

 

 

 
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Pilot Plants

 

DESIGN REPORT

Greywater Treatment Plants

Hammam and Apartment House

Attaouia , Morocco

Zer0-M

July 2007


•  Introduction

The pilot activity in Attaouia is a partnership between the project “Sustainable concepts towards a Zero Outflow Municipality (Zer0-M), mainly the Moroccan partner Institut Agronomique et Vétérinaire Hassan II (IAV Hassan II) in Rabat and the Municipality of Attaouia. Zer0-M is a project in the Euro-Mediterranean Regional Programme for Local Water Management (MEDA Water programme), funded by the European Commission and the national partners of the project.

The pilot activity is mainly meant as a demonstration of sustainable water management solutions as suggested by Zer0-M, which shall to prove that these solutions work under real conditions and ultimately allow the further spreading of the demonstrated techniques. The pilot activity will also help to gain experience with the techniques implemented under real conditions and improve them if necessary until they can be recommended for wide use.

Last but not least they shall help to ease the difficulties in water and wastewater management faced by the fast growing rural centre of Attaouia, a town in a dry climate with constantly increasing water consumption and very limited financial resources for the supply and sound evacuation of the amounts of water required.

•  Situation

The small rural town of El Attaouia has a population of 20 000 inhabitants. It is located in the Province of Kelâa des Sraghna whose main activity is agriculture. El Attaouia has conventional sewerage and a connection rate over 80%. A 1.5 ha treatment plant was constructed for the city to treat an average daily flow of 780 m 3 .

Attaouia is growing at a quite important rate. This has its impact also on the existing wastewater treatment plant, designed by the Moroccan project partner, Mr. El Hamouri. Recently, the Ministry of interior offered to extend the plant to cope with the daily 1,200 m 3 flow. The construction started July first and is scheduled to end October 2007.

As a possible additional measure to both reduce water consumption and the pressure on the wastewater treatment plant segregation and treatment of greywater from the largest city's hammam and of an apartment house are going to be implemented as pilot actions.

Greywater treatment for a public hammam:

Total water demand 150 m³ per day

Greywater treatment for an apartment house:

Apartments 17

Greywater collection from all apartments

Greywater reuse outside and in 4 apartments, corresponding to one vertical feeder line, for toilet flushing

The greywater segregation is expected to have a positive effect on the hydraulic load and treatment performance of the wastewater plant. The pilot at the hammam will have an immediate effect, whereas for apartments this will only be true if the experience is multiplied. The town is planning to implement more greywater systems in future housing developments if the first experiment shows good results.

•  System Requirements

The pilot plants should provide the possibility for safe reuse of greywater in outside uses (landscaping of green areas) and toilet flushing. The systems will be operated as decentralised treatment plants by the municipality, i.e. by skilled personnel. The treatment system of the apartment house will have to be multiplied in great number for cluster housing units in order to have an impact on the town water management. Therefore, it needs to be particularly robust and work safely with little maintenance requirements.

All proposed plants have a small footprint and are best integrated into existing open spaces in the urban landscape with a short water transport distance.

  System Description

•  Water efficiency

Greywater segregation should not be implemented without attention to water saving measures. These will comprise

  • Information of inhabitants about possibilities to contribute to efficient water use, e.g. fixing leaks.
  • Water saver fixtures
  • Double-flush toilets with the smallest possible cistern volume

The water saver fixtures are installed in the apartment following the project recommendations and will be discussed with the hammam owner.

•  Collection and distribution system

Hammam

Greywater and blackwater plumbing are separated inside the hammam where necessary (works are only needed in the women part, as the systems are already separated in the men part down to an outside manhole). Outside the hammam all greywater is collected in a manhole and pumping chamber, which has an overflow to the public sewer.

From the pumping chamber the water is conveyed via a 2000 m pipeline to the treatment plant in the nearest park, where most of the water will be used for landscaping.

The treated water is buffered in a 25 m³ tank before reuse.

A distribution system with outlets at regular intervals for irrigation water in the town is planned. Part of this system is to be immediately implemented to make the reuse of the greywater possible.

Apartments

The greywater collection system in the apartment house was installed during erection of the house as the project is already under discussion for some time. Because of communication problems between the implementing actors (company and municipal engineer) and the project the greywater and the rainwater collection system were combined. This is not ideal but could not be modified anymore. Given the long dry period in Attaouia the results of the greywater treatment will still be representative for similar systems run without rainwater.

Due to the combined collection system an overflow weir is implemented at the street level in front of the house, in order to limit the flow to the treatment system. The greywater flows by gravity to the treatment system at some 60 m of the house. The distance between the building and the treatment plant is not ideal but until such systems are taken into consideration at the time of space use planning, the only possibility is to do with what space is available. At the plant site a pump lifts the greywater into the treatment plant.

The treated water is buffered in a 2,5 m³ tank before reuse. From there a second pump sends the water back into the building where it is distributed to the toilets of four apartments connected to one riser.

•  Greywater treatment

The system suggested for Attaouia is based on a two step constructed wetland successfully tested on greywater of a sports club in Rabat at the TDC of the IAV Hassan II. The treated greywater there is hygienised in a last step with a UV-lamp and than reused for toilet flushing too.

Figure 1 : Greywater constructed wetland at IAV

It is planned, however, to increase the specific bed size, the critical dimension, and to install a siphon ahead of the second step in order to allow true vertical batch feeding. The siphon was developed at the IAV TDC.

Figure 2 : Batch feeding siphon developed at IAV.

Table 1 : Comparison of specific load for reed bed at the IAV Hassan II TDC, the Hammam and the apartment house in Attaouia (st. stage, CW constructed wetland, UV ultraviolet disinfection)

Unit

IAV

Hammam

Apartments

Daily load

m³/d

10

150

4.25

Total area

9

160

8.4

Specific load

mm/d

1,110

940

506

Trains

#

1

2

1

Treatment

2 st. CW + UV

2 st. CW

2 st. CW + UV

A two stage constructed wetland will treat the wastewater to a degree to make it useable for landscaping. The filter beds are made of concrete, the first stage sitting more or less on the ground, the second completely buried. The level difference between the two beds is used to operate the batch feeding system.

Stage one

The first stage constructed wetland consists of a more or less continuously fed horizontal flow coarse filter.

Stage two

The second stage consists of a vertical flow bed filled with fine material with batch feeding. This stage provides the final treatment for the wastewater.

Stage one and two are planted with reed ( phragmites communis ) to enhance the treatment efficiency. The shapes of the beds can be adapted to landscaping requirements in order to integrate them into an overall garden architecture.

To increase operation security the hammam system has two trains in order to be able to switch to one of the two temporarily for maintenance or other activities, which may become necessary.

The apartments system has a screen upstream of the constructed wetland, to prevent coarse material to enter the distribution pipes. A UV lamp is added after the second stage to guarantee hygienisation of the wastewater before reuse in the households (table 1). This measure is not deemed necessary for landscaping purposes.

Table 2 The outlet water quality is expected to comply with the following values:

Quality parameter

Concentration or value

TSS

< 10mg/l

Turbidity

< 2 NTU

COD

< 25 mg/l

BOD 5

< 10 mg/l

TKN

< 10 mg/l

TP

< 1 mg/l

Fecal Coliforms (apartments)

0 CFU/100 ml

The water thus produced has bathing water quality. It is free of solids, has a very low turbidity, a clear colour and is perfectly suitable for irrigation or landscaping. With the UV disinfection added in-house uses, e.g. toilet flushing or laundry washing, can be recommended.

The water is not treated to drinking water quality and should not be used as potable water!

The greywater being only slightly polluted any disturbance by bad odours even by the raw wastewater can be excluded. Due to the aerobic degradation processes the plant itself produces no bad odours.

•  Operation and maintenance requirements

The plants, as any device, will need regular inspection, especially of the screen, the feeding system of the constructed wetlands and the disinfection device. The screen of the apartment plant will have to be cleaned if necessary. No other regular maintenance operation is required.

Three to four times a year the reed would have to be cut to maintain young and fresh looking plants.

In case of failure of any part, this must be remedied. Given the fact that the electro-mechanical equipment and moving parts in general are minimal, failure of equipment can be expected to be rare.

In total, about two working hours per week will be sufficient to maintain the two plants in good conditions. No input of any materials or chemicals is needed.

It must be expected that the pumps have to be replaced every 10 years approximately. The flexible pipes of the siphon may need replacement after a shorter time. No long-term experience is yet available with these pipes. In France similar devices are changed every year regardless of their condition.

In order to guarantee normal operation conditions and keep records of the plant a visit by an expert on a forthnight frequency, combined with a sampling campaign and analysis of inlet and outlet . The maintenance staff will keep a logbook of the status of the plant and maintenance activities carried out.

•  Cost

According to our forecast, the investment and the maintenance costs for the proposed system are reported on table 2.

Table 3 : Construction and maintenance cost of the proposed system (MAD per year)

Item

Unit

Qu.

Unit rate

Amount (MAD)

Amount (EUR)

Cost of treatment system

Hammam

Lump Sum

973.945,23

86.900,00

Apartments

Lump Sum

280.322,34

24.800,00

Operation and Maintenance

Personnel

hours/year

100

20

178,50

2.000,00

Energy

kWh/year

8200

1,1

9020

805,00

The construction cost are valid under the assumption that the works are carried out by a local company under the supervision of the municipal engineer.

 

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