Khaled Medhioub

Effects of partial stone removal on the co‐composting of olive‐oil processing solid residues with poultry manure and the quality of compost

Abstract Full scale composting studies were performed with stoned (SEOOPSW) and non stoned exhausted olive‐oil processing solid waste (NSEOOPSW) mixed with 20% poultry manure to reach a C/N ratio of around 30 and to improve the chemical and microbiological properties of the end products. The experiment was performed on two windrows (3 m wide, 25 m high and 10 tonne weight) to investigate the effects of stone removal and poultry manure addition on composting process efficiency and on the quality of composts. The partially stone removal operation reduced the total composting time by at least one month compared with the untreated waste. The addition of poultry manure improved the chemical quality of the end product as shown by the doubling of the nitrogen concentration after four months composting together with the increased amount of P and K. Compost from stoned exhausted olive‐oil processing solid waste had higher levels of cation exchange capacity (CEC) and humic add content with a lower [FA/HA] ratio indicating a high polymerisation level. Agronomic field test showed that both composts are not phytotoxic. When applied at the rate of 40 tonne ha‐1 to a potato culture, they produced approximately the same yield (46 and 48.5 tonne ha‐1) but they acted differently in terms of plant development Compost produced from the NSEOOPSW acted more positively on the stem length (84.1 against 77.6 cm) and on leaf weight (354 against 238 g), whereas compost from the SEOOPSW more positively affected tuber sizes (76% large grade compared to 55%).

Bioconversion of wastes from the olive oil and confectionary industries: spectroscopic study of humic acids.

Structural changes in humic acids extracted from composted mixtures of sesame bark with the paste of olive mill wastewater or exhausted olive cake, were investigated using FTIR spectroscopy and solid state 13C CP/MAS techniques. The C/N ratio and organic matter degradation decreased significantly after 6 months of composting. The FTIR spectra of humic acids content showed an increase in the aromatic compounds content and a degradation of aliphatic chains. During composting, nuclear magnetic resonance 13C spectral analyses confirmed that aromatic groups exhibited a slight increase while the aliphatic groups decreased and disappeared at the end of the composting process. These results showed that during composting, aliphatic chains were preferentially oxidized, while aromatic macromolecules were bio converted into highly functionalized compounds.

Characterization of olive mill wastes composts and their humic acids: stability assessment within different particle size fractions

Compost stability assessment within different particle size fractions was studied. Humic acids (HAs) were extracted from two kinds of co-composts prepared using evaporated olive mill wastewater (OMSW) or solid waste from olive oil extraction (OC) and poultry manure (PM). The elemental composition, Fourier-transform infrared spectroscopy (FTIR) and 13C-NMR (nuclear magnetic resonance) analysis and molecular weight distribution were investigated to assess the composted organic matter stability in different fractions. In both composts, organic matter content was higher in the>2 mm fractions than in the<2 mm fractions, because of fractions’ richness in hardly biodegradable compounds. Spectroscopic analysis revealed that OMSW compost fraction<2 mm and OC compost 2–4 mm fraction were rich in aromatic compounds and oxygenated groups but poor in aliphatic structure. Moreover, the HA distribution reflected a high stabilized compost<2 mm fraction, especially from evaporated effluent known as phytotoxic. However, the 4–6 mm fraction included high aliphatic compounds besides aromatic structures and did not exhibit any phytotoxicity, confirming compost fraction maturity. However, the low C/N ratio, the high OMSW compost mineral nutritive elements and the high aromatic C rate reflected highly stabilized products. Consequently, the performance of both prepared organic fertilizers for agriculture use contested the previous negative effect ascribed to olive mill wastewater.

Evaluation of Compost Maturity, Hydrophysical and Physicochemical Properties: Indicators for Use as a Component of Growing Media

The cocomposting of agricultural waste is a new management priority in Tunisia. In this study, four composts were evaluated by comparing the changes in measured hydrophysical and physicochemical properties and phytotoxicity. The organic wastes used were almond shell (AS), sesame bark (SB), olive husk (OH), and green and wood wastes (GW and WW, respectively). Composts CI and CII were composed of AS/SB and OH/SB, respectively, at a ratio of 75/25 (wet weight basis). CIII consisted of OH, SB and CAS (coarsely-ground almond shell used as a bulking agent) at a ratio of 55/25/20. Finally, CIV was composed of 25%SB+9%CAS+18%GW+48%WW. The composts studied were characterized by basic pH and an electric conductivity (EC) value ranging from 1.6 to 2.4 mS/cm. The organic matter contents (OM) and C/N ratios of composts ranged from 20 to 46% and from 10 to 21%, respectively. Based on hydrophysical analyses, composts CI, CIII and CIV, containing AS, were shown to have a porosity and a water content of 10-26% and 10-20%, respectively. The phytotoxicity of composts was studied on the basis of cress seed germination. Results revealed that differences in properties are mainly related to the nature of composted waste and that some of these composts are compatible for use as constituents in growing media for horticultural soilless cultures.

Geochemical behaviour of the aerosol sampled in a suburban zone of Sfax City (Tunisia)

This work examines the geochemistry of the soluble elements (Ca2+, Mg2+, Fe2+ + Fe3+, Na+, K+, NH4+, Cl−, NO3−, SO42− and PO43−) present in the aerosol collected from a suburban site in Sfax City (Tunisia), which is frequently subjected to the urban plume. The descriptive study showed the influence of enrichment sources and meteorological factors. Complementary statistical approaches based on principal component analysis and multiple linear regression showed that the sampled aerosol has three different origins: crustal, marine and anthropogenic. The corresponding components are respectively made of (Ca2+, Mg2+, Fe2+ + Fe3+, K+ and PO43−), (Cl− and Na+) and (SO42−, NH4+ and NO3−). The contribution of the first two components is shown to depend on seasonal effects caused by two antagonistic circulations of continental and marine winds. The contribution of the anthropogenic component (SO42−, NH4+ and NO3−) is shown to be related to the effect of dominant north-easterly winds, which carry the pollution of Sfax City to the study site. Statistical approaches related to the behaviour of these anthropogenic compounds, in the presence of secondary aerosol precursors (SO2, NO2), proved their dependence on gas/particle conversion processes, especially those of neutralisation.

Polyphenolic compounds progress during olive mill wastewater sludge and poultry manure co-composting, and humic substances building (Southeastern Tunisia)

In Mediterranean areas, olive mill wastes pose a major environmental problem owing to their important production and their high polyphenolic compounds and organic acids concentrations. In this work, the evolution of polyphenolic compounds was studied during co-composting of olive mill wastewater sludge and poultry manure, based on qualitative (G-50 sephadex) and quantitative (Folin–Ciocalteu), as well as high pressure liquid chromatography analyses. Results showed a significant polyphenolic content decrease of 99% and a noticeable transformation of low to high molecular weight fraction during the compost maturation period. During this step, polyphenols disappearance suggested their assimilation by thermophilic bacteria as a carbon and energy source, and contributed to humic substances synthesis. Polyphenolic compounds, identified initially by high pressure liquid chromatography, disappeared by composting and only traces of caffeic, coumaric and ferulic acids were detected in the compost. In the soil, the produced compost application improved the chemical and physico–chemical soil properties, mainly fertilising elements such as calcium, magnesium, nitrogen, potassium and phosphorus. Consequently, a higher potato production was harvested in comparison with manure amendment.

Geochemical behaviour of PM10 aerosol constituents under the influence of succeeding anticyclonic/cyclonic situations: case of Sfax City, southern Tunisia

The present study investigates the geochemical behaviour of PM10 aerosol constituents (Cl, Na, Si, Al, Ca, Fe, Mg, Mn, Pb, Zn, S) at Sfax City (Tunisia) under succeeding meteorological conditions, including short-lived anticyclonic, cyclonic and prolonged anticyclonic situations. The results revealed daily total concentrations fluctuating between 4.07 and 88.51xa0μg/m3. The highest level recorded was noted to occur under the effect of the short-lived anticyclonic situation characterized by low wind speeds. It was 1.5 times higher than those recorded during cyclonic and long-lived anticyclonic situations characterized by moderate to high wind speeds. During the cyclonic situation, the marked increase of (Na and Cl) concentrations is associated with relatively high sea wind speeds (6 to 9xa0m/s), which are in turn responsible for a slight increase of crustal elements such as Al, Ca, Si, Fe and Mg, by the entrainment in the air of dust from roads and undeveloped areas. During the two anticyclonic situations, the simultaneous increase (due to communal transport) of crustal (Ca, Si, Al, Fe, Mg) and man-made (Mn, S, Pb, Zn) elements was noted to be associated with the dominance of terrigenious wind flows with speeds varying between 1.5 and 4xa0m/s. However, the significant contribution rates observed for Cl under the prevalence of such winds as compared to other crustal elements such as Fe suggested the influence of the sebkhas of Southern Tunisia.

Spatiotemporal Variation of Particulate Fallout Instances in Sfax City, Southern Tunisia: Influence of Sources and Meteorology

Particles deposition in the main industrial zone of Sfax City (southern Tunisia) was studied by weekly monitoring particulate fallout instances at twenty sites from November 11, 2012, to April 15, 2013. Very high fluctuation in those particle fluxes, ranging from 0.376 to 9.915u2009g/m2, was clearly observed. Spatiotemporal distribution of the deposited particulate fluxes and the exposure of each site to the main industrial plumes (i.e., phosphate treatment plant “SIAPE,” soap industry “SIOS-ZITEX,” and lead secondary melting industry “FP Sfax Sud”) indicated the concomitant effects of surrounding industrial sources. In addition, the highest particulate deposition seemed to be associated with predominant strong cyclonic situations. Those deposition rates exceeded the levels recorded in the case of strong stabilities, considered as responsible for pollutant accumulation.

Seasonal evolutions of ozone (O3) and its nitrogen precursors (NO, NO2) in urban Sfax (Tunisia)

Seasonal evolution of ozone (O3) and its nitrogen precursors (NO, NO2) in downtown Sfax (Tunisia) was monitored. Nitrogen oxides are shown to be closely related to local vehicle sources. Seasonal ozone levels, however, are shown to be dependent on regional meteorological conditions. High ozone levels are due to the effect of anticyclones and stratosphere intrusions (cut-off lows). Low levels are associated with cyclonic conditions of small vertical range of motion. Other than these particular conditions, ozone levels are shown to be relatively higher in fall and winter seasons, characterised by a very steady atmosphere. Overall, the examined meteorological conditions, the ozone concentrations observed in downtown Sfax are characterised by clear day/night cycles, which can be explained by the significant ventilation of the region.

Cocomposting of Olive Mill Wastewater with Manure and Agro-industrial Wastes

The use of olive mill wastewater (OMW) for composting was studied by the addition of this liquid waste to a mixture of olive husks, poultry manure and confectionery wastewater. The composting process was compared with that of another pile of similar composition, but without olive mill wastewater. In order to study the effects of both composts on plant yield and soil properties, a field experiment was carried out with potato. Three amendments were applied: manure and two composts with same rate 30 tonnes/ha. The olive mill wastewater addition produced compost with higher organic matter concentrations and higher electrical conductivity, and a stabilized and humified organic matter lower than the compost produced without olive mill wastewater. The olive mill wastewater compost application to soil did not injure plants, producing a similar plant yield to both compost without olive mill wastewater and manure. The olive mill wastewater compost application to soil also improved the chemical and physicochemical properties of the soil mainly fertilizing elements such as calcium, magnesium, nitrogen, potassium and phosphorus. With respect to potato yield, both composts showed higher plant production in comparison to manure, reaching a potato yield of 46 and 47 t/ha in amended soil with compost with and without OMW, respectively.