Enzo Montoneri

Benefits for agriculture and the environment from urban waste

Soluble bio-based substances (SBO) that have been isolated from urban biowaste have recently been reported to enhance plant leaf chlorophyll content and growth. The same SBO have also been shown to enhance the photochemical degradation of organic pollutants in industrial effluent. These findings suggest that SBO may promote either C fixation or mineralization, according to operating conditions. The present work aims to investigate SBO performance, as a function of source material. Thus, three materials have been sampled from a municipal waste treatment plant: (i) the digestate of the anaerobic fermentation of a humid organic fraction, (ii) a whole vegetable compost made from gardening residues and (iii) compost made from a mixture of digestate, gardening residues and sewage sludge. These materials were hydrolyzed at pH13 and 60°C to yield SBO that display different chemical compositions. These products were applied to soil at 30, 145 and 500 kg ha(-1) doses for tomato cultivation. Soil and plant leaf chemical composition, plant growth, leaf chlorophyll content and CO2 exchange rate as well as fruit quality and production rate were measured. Although it did not affect the soils chemical composition, SBO were found to significantly increase plant photosynthetic activity, growth and productivity up to the maximum value achieved at 145 kg ha(-1). The effects were analyzed as a function of SBO chemical composition and applied dose. The results of this work, compared with those of previous works, indicate that urban biowaste, if properly exploited, may furnish conjugate economic and environmental benefits, within a friendly sustainable ecosystem.

A new, sustainable LaFeO3 material prepared from biowaste-sourced soluble substances

For the first time, sustainable LaFeO3 powders were prepared from soluble bio-based substances (SBO) extracted from urban wastes. For the preparation of the perovskite-type powders, a modified solution combustion synthesis route was used, where SBO have the triple role of fuel, complexant and microstructural templates. A careful examination of the LaFeO3 powders, using complementary characterization techniques, evidenced their peculiar microstructural, morphological, textural and photocatalytic properties. Preliminary photodegradation tests of a phenol-based wastewater pollutant and photobleaching of a model dye were performed on the waste-derived and reference LaFeO3 powders; the obtained results encourage further studies on the application of these materials as heterogeneous catalysts for wastewater treatment. Moreover, a meaningful amount of entrapped matter was evidenced in the powders, which is responsible for most of their peculiar properties.

Horticultural and Floricultural Applications of Urban Wastes Originated Fertilizers

Different origin composts and a digestate from a biogas plant and their respective alkali soluble (SBO) and insoluble (IOR) fractions have been tested as organic fertilizers in growth media. The materials have been characterized by determination of pH, salinity, C, N, P, and K content. A preliminary evaluation of the possible phytoxicity has been performed by determination of the germination indexes of cress (Lepidium sativum), white mustard (Sinapsis alba) and radish (Raphanus sativus). Most of the materials did not promote the germination of the seeds. Notwithstanding these negative results, the materials were also used as partial peat substitute in a commercial substrate to test the growth of marigold (Tagetes patula), radish (Raphanus sativus), and spinach (Spinacia oleracea). The dimension and dry weight of the plants grown on the substrate mixed with the composts, the digestate or the SBOs were similar to those observed on the substrate. Moreover, most of the SOBs provoked the increase of the dry weight of the roots of the radishes, therefore an increase of the quality. The insoluble fractions (IOR) from the composts allowed a growth of the plants similar to that obtained with a commercial substrate. In contrast, the IOR obtained from the digestate was phytotoxic.

Soluble Bio-based Substances Obtained from Urban Wastes: Isolation and Characterization

The organic fraction of urban wastes can be considered a cost effective source of added value products for a wide number of uses. The present chapter describes different possible strategies for the treatment of organic wastes, used at the present time in many waste treatment plants. Subsequently the chapter deals with the isolation process of soluble bio-based substances (SBO) from urban biowastes at both laboratory and pilot plant scale. A detailed description of SBO composition and physical-chemical characterization is given.

Ecofriendly in-line process monitoring: a case study. Anthracene photodegradation in the presence of refuse-derived soluble bio-organics.

Photodegradation of anthracene has been studied in aqueous solutions containing soluble bio-organic substances isolated from urban refuse. To perform a preliminary rapid feasibility study of this process while reducing the amount of analytical effort and reagents, an experimental set-up was developed comprising a Teflon coil surrounding a UV-lamp and coupled with an in-line spectrofluorimeter. In this fashion only few millilitres of solution are needed to study the degradation process. Furthermore, the in-line spectroscopic approach enables monitoring of the process without consumption of reagents. Additional studies by liquid chromatography and use of toxicity tests clearly indicated that the apparent inhibition effect of bio-organic compounds on anthracene degradation is not relevant. The results imply that urban refuse may be used as an auxiliary in the recovery of polycyclic aromatic hydrocarbons from contaminated soil by washing, without deleterious effects on the photodegradation of anthracene and other aromatic pollutants.