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In order to enhance the profitability of the available sanitation facilities and equipments, a Directorate of Research & Development was set up in 2000. Pilot research projects are conducted on the sites of sanitation facilities. Their major objective is to enhance the quality of the treated wastewater and sludge, as well as to achieve better control over these products and promote their use. ONAS has always sought to ensure that research work be conducted within a cooperation network allowing an exchange of experience and expertise, as well as to stimulate a positive interaction between all competencies whether they be in higher education schools and research centres or they be found among industrialists with experience in modern technologies. The research subjects concerned relate to the following fields:
water treatment
sludge treatment
treatment of gases emitted by sanitation facilities;
reuse of treated wastewater;
energy conservation;
network operation;
technical reporting.

ONAS conducts additional treatment in order to remove microbial pollution, phosphorous and nitrogen in certain wastewater treatment plants located in the vicinity of sensitive water mediums, as well as to prevent health-related hazards, according to the final destination of treated wastewater disposal.
Research work :
sand filtration (percolation);
sterilisation by ultra-violet rays;
algae-based treatment;
sanitation of small population settlements;
ways of gaining better control over secondary treatment.
Objectives:
preserving water quality according to the specifications of water disposal;
treatment of the treated wastewater disposed of in the recipient medium and reused for irrigation purposes;
gathering acquaintance with the major design requirements and technical features related to modern technologies;
providing advice as to selecting the best treatment model;
setting recommendations for the operation & maintenance (O & M) of modern technologies.

The research & development activities include the transfer of modern technologies which they seek to harness to finding appropriate solutions for reducing the volumes of sludge based on treatment.
Research work:
identifying the chemical constituents of sludge, such as to direct the use of mechanical treatment equipment;
participation in the preparation of a draft regulation on the technical specifications of the use of sludge;
use of sludge in other than spreading purposes (farming);
seeking out a treatment process likely to reduce sludge volumes.


In its concern to protect the environment and mitigate the adverse impacts of the sanitation networks, especially in the summer season, ONAS undertakes to upgrade and renovate certain sanitation facilities that have become, due to urban expansion, close to urban centres. ONAS research & development programme comprises control over the treatment of gases in certain facilities based on chemical or deodorant products, as well as on biological processes.
Research work:
diagnosis of the current biological processes and use of chemical products with a view to: enhancing the profitability of the current processes;
seeking out the product best suited for bacterial growth in order to reduce gases;
ascertaining the efficiency of combating gases by the use of chemical products and control over such products.

The reuse of treated wastewater is considered, in the Tunisian context, as a judicious solution in order to address the scarcity of rain and the climatic conditions, in addition to its being an additional water resource allowing an extension of irrigated farming zones, green spaces and golf courses. Alongside with the Strategic Study on the Use of Treated Wastewater, there are other research & development subjects underway which relate to additional treatment (beyond secondary treatment), and this with a view to further valorising a safe reuse of treated wastewater in farming and according to the needs of the farmers, as well as extending the scope of its use in other fields, which would increase the rate of such reuse.
Research work:
technical aspects of the reuse of treated wastewater: increasing the rate of treated wastewater reuse
monitoring the nutritional value, the impacts of microbial pollution, the physical-chemical features and the rate of heavy metals in relation to the farming products irrigated by secondary treatment wastewater;
monitoring the farming products irrigated by additionally treated wastewater;
monitoring the irrigation of other plants than those already listed, and this with a view to updating the organisational and legal aspects;
monitoring the agricultural production irrigated by treated wastewater;
monitoring the rate of heavy metals in the soil and in aquifers, and study of mineral accumulation in treated wastewater irrigated lands.
Objectives:
the extent of adaptation of the treatment technologies adopted to the local conditions and expected goals;
ascertaining the absence of negative impacts on the environment and agricultural production in order to ensure safe reuse of treated wastewater for the development of the agricultural sector, which would have a positive impact on economy.

The current research works include selecting the appropriate equipment (use of compressed air system and surface aeration) which ensures the necessary rate of oxygen for the treatment operation (BOD). The research work undertaken aims at reducing the energy cost and, accordingly, the wastewater plant operating cost.
 ONAS has always endeavoured to use NICTs in the various areas of speciality, and this based on a comprehensive programme aimed at generalising communication to further enhance its services. The programme includes research works related to improving the operation services.
Research work:
establishment of a remote control and monitoring system for sanitation facilities;
design of computer-based software.
 Technical reports have been drafted on:
Treatment of wastewater and sludge:
filtration techniques;
filtration through fine membranes;
evaluation of the filtration and ray-based additional treatment;
integrated wastewater treatment plants for the sanitation of small-sized housing settlements;
mechanical and incineration treatment techniques of sludge.
Treatment of gases emitted by sanitation facilities
evaluation of processes of treatment of gases emitted by sanitation facilities;
evaluation of the chemical products used for combating such gases.
Reuse of treated wastewater
inventory of risks;
study on increasing the rate of reuse of treated wastewater;
monitoring the impacts of treated wastewater on the soil and the deep-lying aquifer;
evaluation of the agricultural products irrigated by treated wastewater.
Energy
monitoring the various aeration systems and appreciating their impact on the treatment process based on aeration ponds.

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