Re-use of water from wastewater treatment plants

According to a report published by the United Nations (UN) on “World Perspectives on Population 2019”, the world’s population is expected to be 9.7 billion by 2050 and 10.9 billion by 2100. Recognizes both the limitation of water resources and the increase in water consumption worldwide in parallel with the rapid population growth. This, in turn, necessitates the reuse of water, which has actually been applied through various techniques from ancient times. Water reuse represents a potential for sustainable water management and contributes to reducing the use of fresh water.

Water reuse has many benefits, such as the provision of drinking water, especially in countries with water shortages, improved agricultural production, reduced energy costs associated with production and all other significant environmental benefits.

The most important two factors to consider when implementing different targets in the scope of water reuse are energy efficiency and sustainability. Wastewater reuse remains an appropriate option for optimizing drinking water consumption. Among the many challenges is to convince not only the communities but also the political elite. A number of barriers, including cultural beliefs, to investment opportunities continue to negatively affect the progress of water reuse. A key factor for successful implementation of wastewater reuse is public acceptance, which can be ensured by the high quality of the reclaimed water.

Waste Water Treatment Plants in Bulgaria

Figure 1 shows the distribution of water used by sectors on average in the world, in developing countries and in the western (developed) countries.

Climate change necessitates the preparation of a project on “Reuse of Waste Water in Bulgaria”. The project should aim to examine national and international practices and standards for the reuse of urban and industrial wastewater, proposing technical and administrative criteria for establishing a legal framework for the reuse of wastewater specific to Bulgaria.
With the project, all WWTPs in place and functioning should be investigated to determine wastewater reuse targets. In this way, information will be generated to clarify the possibilities for efficient and sustainable re-use of WWTP waters.
The following processes for re-use in WWTP are common:

• Pressurized multimedia sand filter + UV disinfection
• Pressurized multimedia sand filter + Chlorine disinfection
• Pre-chlorination + Pressurized multimedia sand filter + UV disinfection + Final chlorination
• Pressurized multimedia sand filter + Activated Carbon + UV disinfection
• Pressurized multimedia sand filter + Ultrafiltration + Chlorine disinfection
• Rapid Sand Filter + UV disinfection
• Rapid Sand Filter + Chlorine disinfection
• Mechanical Filter + UV disinfection
• Mechanical Filter + Ultrafiltration
• Disc Filter + UV disinfection
• Pre-chlorination + Pressurized multimedia sand filter + UV disinfection + Ozonation + Final chlorination
• MBR + UV Disinfection

In order to update the preparation of the correct methodology and regulation for waste water reuse, a detailed study should be carried out, including:

• Research Study of the national legislation in force;
• Assessment of existing wastewater treatment technologies, efficiency of water reuse treatment, etc .;
• Assessment of international experience;
• Evaluation of the development of purification technologies;
• Assessment of environmental and public health impacts of pollutants in reclaimed wastewater;Assessment of regulatory practices in the world (USA, EU, Singapore, Australia, Spain, Italy, France, Israel, etc.);
• A thorough assessment of the 2012 US Water Regulatory Guidelines;
• Determination of technical regulation criteria specific to Bulgaria.

• Assessment of regulatory practices in the world (USA, EU, Singapore, Australia, Spain, Italy, France, Israel, etc.);
• A thorough assessment of the 2012 US Water Regulatory Guidelines;
• Determination of technical regulation criteria specific to Bulgaria.

Water consumption for drinking, industrial and irrigation needs is expected to increase significantly in the coming years. As a result of increasing demand, drought and pollution in catchment areas, the amount of water currently available will reach its threshold.
The main problems encountered in the management of water resources are the inadequacy of planning, monitoring, evaluation and control and poor coordination between organizations.
Wastewater treatment plants should be treated as a source of raw materials, energy and water recovery. We, as a society and a state, should use water efficiently in the process of irrigation in agriculture, water supply, industrial use and any other process.
We at ENGINEER believe it is time to take adequate measures related to wastewater reuse.

REFERENCE DOCUMENTS
• Alcalde-Sanz, L. & Gawlik, B. M. Minimum Quality Requirements for Water Reuse in Agricultural Irrigation and Aquifer Recharge: Towards A Water Reuse Regulatory Instrument at EU Level. EC – Joint Research Center, Directorate D, Via Enrico Fermi 2749, I-21027, Ispra, Italy.
• Al-Jayyousi, O. R. Greywater reuse: towards sustainable water management. Desalination 156 (1–3), 181–192.
• Angelakis, A. N., Asano, T., Bahri, A., Jimenez, B. & Tchobanoglous, G. Water reuse: from ancient to modern times and the future. Frontiers in Environmental Science 6, 26.
• Asano, T., Maeda, M. & Takaki, M. Wastewater reclamation and reuse in Japan: overview and implementation examples. Water Science and Technology 34 (11), 219–226.
• EPA (U.S. Environmental Protection Agency) Guidelines for Water Reuse. EPA / 625 / R-04/108. Environmental Protection Agency, Washington, D.C, USA.
• EPA (U.S. Environmental Protection Agency) Guidelines for Water Reuse. EPA / 600 / R-12/618. Environmental Protection Agency, Washington, D.C, USA.
• Hyde, K. An evaluation of the theoretical potential and practical opportunity for using recycled graywater for domestic purposes and Ghana. Journal of Cleaner Production 60, 195–200.