A Research Project Addressed to No-Food Crop Production by Municipal Wastewater Irrigation

Santonoceto C., Stran A., Mediterranean University of Reggio Calabria, Italy
Toscano A., University of Catania, Italy
Zema D. A., Zimbone S. M., Mediterranean University of Reggio Calabria, Italy

1. Foreword. Biomass from no-food crops represents a renewable source of thermal, electric (by thermal-electric plants) or thermo-electric (in combined heat and power plants) energy. The interest in energy produced by no-food crops is based on both environmental advantages (as the zero balance of carbon dioxide and the reduced issues of pollutant compounds, Venturi and Venturi, 2003) as well as the related economic and social spin-offs, as the reduction in dependence on fossil fuel utilisation, the diversification of energy sources and the enhancement of development possibility for marginal lands (widely available in many rural zones of Mediterranean basin) (Tolbert and Schiller, 1995).

On the other hand, the technologies (both for supply and transport phases as well as conversion processes) for energy conversion of biomass still need to be optimised, particularly from the economic point of view (Lewandowski et al., 2000). Nowadays, the energy conversion of no-food crops is mainly limited to experimental or demonstrative plants with a few exceptions: in Italy, for example, there are few production plants operating with industrial standards, even though the biomass availability could even fulfil up to the 14 % of the energy demand (Hoogwijk et al., 2003).

The increase in the efficiency levels of energy conversion and the decrease at the same time of the exploitation costs (for example by reducing the input factors of no-food crops production and conversion processes) are thus needed in order to maximize the profits and realize the above mentioned environmental and social spin-offs. Moreover, the agricultural recycling of poor quality water for no-food crops irrigation, particularly advisable in some contexts as the Mediterranean basin, characterised by a chronic water resource shortage, offers three advantages:
—  the possibility to dispose of an easy and efficient method for wastewater disposal;
—  the conservation of good quality water resources for different purposes;
—  the recover of natural cycles of organic matter and nutrients within the soil by the exploitation of wastewater fertilising properties (Jimunez-Cisneros, 1995).

2. Aims of the research. The need to provide useful information on biomass yields and energy production of no-food crops in relation to input factors has recently stimulated a wide experimental activity involving four Research Units (RU) in as many Italian universities (within the national research project «PRIN 2007»): Bologna, Catania, Padua and Reggio Calabria. On the basis of common protocols each RU has set up an experimental site, cultivating different species of wetland plants (able to easily adapt to low quality water and not requiring particular cultivation techniques) irrigated with water of different source. Four main herbaceous species have been tested by each university in the own experimental fields; particularly, each university has planted one of the four species in own largest plot and the other ones in smaller plots, in the way that, on the whole, all the four main species have been tested in the larger plots. The specificity of each RU has been given by the different environmental conditions as well as by the water quality and the irrigation method utilised (Table).

Scheme of experimental activities on no-food crops production through irrigation with treated wastewater carried out by the four Research Units (RU) 

In this paper the experimental method and the expected results of the Research Unit of Reggio Calabria are briefly reported.

3. Experimental methodology. In the experimental site of the RU of Reggio Calabria, located in a marginal agricultural land, Typha latifolia is cultivated in the largest plots (500 m²), while Lytrum salicaria, Arundo donax, Phragmites australis (common to other RUs) in plots of 10 m². The soil texture is sandy loam.

Each species is irrigated by lateral infiltration with both conventional water (control plots), as well as effluents of the settlement tank of a close biological plant depurating wastewater of a small municipality (about 4 000 persons equivalent).

The main chemical and physical properties of the primary treatment effluents and soil are characterised through periodic evaluations of the following parameters: pH, electric conductivity, COD, organic matter, total phosphorus, nitrogen and metal trace contents. Total suspended solids and cation exchange capacity are also determined for wastewater and soil respectively.

For all theses the growth of the crops, their productivity in terms of biomass yield and other effects due to irrigation with both wastewater and conventional resources are assessed by surveys of biological and morphometric parameters. The calorific values and moisture content are determined from biomass samples by a calorimeter in order to evaluate the energy yield.

In order to draw indications about the soil depuration capacity, the physical and chemical properties of percolate released after irrigation with urban wastewater are evaluated through a sub-surface collecting system properly arranged in the less extended plots; laboratory comparative tests for determination of organic load (mainly trough COD evaluation) accumulated in saturated and drained soil samples are carried out.

Economical analysis aims at evaluating the incidence of the different input factors required by cul­tivation, irrigation and conversion phases of no-food crop exploitation for energy production.

4.  Expected results. From this research activity useful indications are drawn with respect to:
—   the productive yields, expected to result basically similar, or even higher, to those attainable by irrigation with conventional water;

—   the economical sustainability of no-food crops production, which is expected to be high thanks to the moderate input factors requirements;

—   the possible environmental benefits, mainly linked to the improvement of soil fertility and its physical-chemical properties, thanks to the organic matter and nutrient addition through the wastewater application, as well as the reduction of pollution risks of water courses, due to wastewater pouring.

5.  Conclusion. The experimental investigations allow drawing useful indications on the effective technical, environmental and economic feasibility for energy exploitation on a full scale of no-food crops irrigated with urban wastewater. The results of these research activities not only seem to be interesting for the scientific community, but could benefit also farm managers, energy production companies, wastewater treatment plant managers, energy sector consumers as well as environmental control and safeguard administrators.

The work has been carried out with equivalent contributions of the authors.

Сведения об авторах

Santonoceto Carmelo, Department of Agro-Forest and Environmental Science and Technology, Mediterranean University of Reggio Calabria, Localita Feo di Vito, I-89122 Reggio Calabria, Italy. Tel./fax (0965) 31-26-81. E-mail
Strano Alfio, Department of Agro-Forest and Environmental Science and Technology, Mediterranean University of Reggio Calabria, Localita Feo di Vito, I-89122 Reggio Calabria, Italy. Tel./fax (0965) 31-26-81. E-mail
Toscano Attilio, Department of Agricultural Engineering, University of Catania, Via S. Sofia, 100, I-95123 Catania, Italy. Tel. (095) 714-75-44, fax (095) 714-76-00. E-mail
Zema Demetrio Antonio, Department of Agro-Forest and Environmental Science and Technology, Mediterranean University of Reggio Calabria, Localita Feo di Vito, I-89122 Reggio Calabria, Italy. Tel./fax (0965) 31-26-81. E-mail
Zimbone Santo Marcello, Department of Agro-Forest and Environmental Science and Technology, Mediterranean University of Reggio Calabria, Localita Feo di Vito, I-89122 Reggio Calabria, Italy. Tel./fax (0965) 31-26-81. E-mail

© Последние изменения внесены 10.10.09

© EcoInform