Safe reuse of treated wastewater in agriculture in Lebanon.
DE GISI S., CELLAMARE C., CASELLA P., FARINA R.
Project report or deliverable
The agricultural use of treated, partially treated or untreated wastewater or surface water contaminated with wastewater is common. An estimated 20 million hectares worldwide are irrigated with wastewater, more of it with untreated than treated wastewater. This misbalance in favour of untreated wastewater will continue to increase as long as the pollution of streams, by effluents from growing urban populations is not matched by treatment facilities. The increasing global scarcity of good-quality water will turn wastewater irrigation from an undesirable phenomenon into a necessity wherever agricultural water demand is not met by supply. This is not only the case in drier Regions, but anywhere where farmers seek land and water to address market demand. Common examples are urban and peri-urban areas in most developing countries where clean water sources are hardly sufficient even to meet domestic demand. The use of untreated wastewater, or polluted water in general, poses risks to human health since it may contain excreta-related pathogens (viruses, bacteria, protozoan and multicellular parasites), skin irritants and toxic chemicals like heavy metals, pesticides and pesticide residues. When wastewater is used in agriculture, pathogens and certain chemicals are the primary hazards to human health by exposure through different routes. These exposure routes are mainly contact with wastewater (farmers, field workers and nearby communities) and consumption of wastewater-grown produce (consumers). Considering the Lebanese situation, the aim of this work is to improve the system of knowledge in terms of agriculture wastewater reuse. It is well known as the addressed issue is multi-disciplinary and complex. Consequently, a long-term approach should be defined. Short of that, certain cornerstones in terms of wastewater reuse should be considered. The graphical representation reported above highlights the methodology defined in this work. Both the direct reuse (defined as the use of treated wastewater in agriculture after storage) and the indirect one (defined as the use of river water in agriculture by means of a pumping) were considered. According to the DPSIR model (Driving forces; Pressures; State of the Environment; Impacts; Responses), it was possible to define the line of actions to achieve our gaols. In particular, two type of actions were considered: • regulations and technological aspects in the field of wastewater reuse in agriculture, by acting directly on the pressures; • monitoring systems for the improvement of the river water quality, by acting directly on the state of the environment.
In this way, we have tried to address the issue in a more complex possible way. Therefore, the report is divided into two parts: • Part I (indicated as the 'knowledge system'), that contains information about (i) specific regulations for agriculture reuse, (ii) monitoring systems for water quality of rivers (indirect reuse) and (iii) technologies to be implemented for the design of wastewater treatment plants (WWTPs); • Part II (indicated as the 'case study'), in which, on the base of a specially methodology defined in this study, the applicability of the recent FAO proposal for Lebanese wastewater reuse in agriculture (FAO, 2010) has been verified, considering the case study of the Ablah WWTP.
Among the many proposal available in literature, we decided to investigate this FAO proposal according to the Lebanese Ministry of Environment suggestion. Finally, the work contains some important suggestions in order to improve the safe agriculture wastewater reuse considering the Lebanese situation.
DE GISI S., CELLAMARE C., CASELLA P., FARINA R. (2014). Technical report for the Ministry of Environment of Lebanon. Cooperation between ENEA and Cooperazione Italiana allo Sviluppo in Libano e Siria, June 2014.