Energetic Valorization of Wet Olive Mill Wastes through a Suitable Integrated Treatment: H2O2 with Lime and Anaerobic Digestion

Siciliano, Alessio; Stillitano, Maria Assuntina; Limonti, Carlo

doi:10.3390/su8111150

Cited by 18 publications

(23 citation statements)

References 42 publications

(40 reference statements)

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“…Furthermore, taking into account the COD value of the inlet mixture and the above value of OLR, the required retention time (RT) for digestion process results is around 25 days. Both the values of RT and OLR are comparable with the ranges considered for the co-digestion of other types of substrates [6,7,9,11]. The above values are theoretical estimates that must be verified by means of semi-continuous tests.…”

Section: Performance Of the Co-digestion Processsupporting

confidence: 52%

Biofuel Production and Phosphorus Recovery through an Integrated Treatment of Agro-Industrial Waste

et al. 2018

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The present study aimed to develop an integrated treatment of agro-industrial waste for biofuel (biogas and syngas) production and for phosphorus recovery. In the first step, an anaerobic digestion (AD) process was carried out on two different mixtures of raw agro-industrial residues. Specifically, a mixture of asparagus and tomato wastes (mixture-1) and a mixture of potatoes and kiwifruit residues (mixture-2) were investigated. The results proved that the properties of mixtures notably affect the evolution of the digestion process. Indeed, despite the lower organic load, the maximum biogas yield, of about 0.44 L/gCOD removed , was obtained for mixture-1. For mixture-2, the digestion process was hindered by the accumulation of acidity due to the lack of alkalinity in respect to the amount of volatile fatty acids. In the second step, the digestates from AD were utilized for syngas production using supercritical water gasification (SCWG) at 450 • C and 250 bar. Both the digestates were rapidly converted into syngas, which was mainly composed of H 2 , CO 2 , CH 4 , and CO. The maximum values of global gasification efficiency, equal to 56.5 g/kgCOD, and gas yield, equal to 1.8 mol/kgTS, were detected for mixture-2. The last step of the integrated treatment aimed to recover the phosphorus content, in the form of MgKPO 4 ·6H 2 O, from the residual liquid fraction of SCWG. The experimental results proved that at pH = 10 and Mg/P = 1 it is possible to obtain almost complete phosphorus removal. Moreover, by using the scanning electronic microscopy, it was demonstrated that the produced precipitate was effectively composed of magnesium potassium phosphate crystals.

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Section: Performance Of the Co-digestion Processsupporting

confidence: 52%

Biofuel Production and Phosphorus Recovery through an Integrated Treatment of Agro-Industrial Waste

et al. 2018

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“…In this regard, reducing the VFA/ALK ratio to a value of about 0.3 g CH 3 COOH /g CaCO 3 , considered to be adequate to properly perform the anaerobic digestion process [24], by maintaining, in the same time, the pH value comprised between 6.5 and 8, was established. Often, lime was used to compensate the acidity of wastes fed in the digesters or it was added directly in the reactors to counteract a possible excess of VFA production [31]. However, Ca(OH) 2 can cause the incorporation and the precipitation of suspended organic matter reducing the availability of substrate for biogas production [31].…”

Section: Pretreatment Testsmentioning

confidence: 99%

“…The performances of anaerobic treatments, besides the reactors type and the operating conditions, are largely affected by the feedstock properties [26]. The applicability of digestion processes for the treatment of many types of organic residues has been investigated in the last years [27][28][29][30][31]. However, few studies have been focused on the treatment of compost leachate by means of anaerobic reactors.…”

Section: Introductionmentioning

confidence: 99%

Biogas Generation through Anaerobic Digestion of Compost Leachate in Semi-Continuous Completely Stirred Tank Reactors

et al. 2019

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The composting process of organic fraction of municipal solid waste, besides to the residual compost, generates a wastewater that is characterized by a high organic load. The application of anaerobic processes represents an advantageous solution for the treatment and valorization of this type of wastewater. Nevertheless, few works have been focused on the anaerobic digestion of compost leachate. To overcome this dearth, in the present paper an extensive experimental investigation was carried out to develop and analyse the anaerobic treatment of young leachate in completely stirred tank reactors (CSTR). Initially, it was defined a suitable leachate pretreatment to correct its acidic characteristics that is potentially able to inhibit methanogenic biomass activity. The pretreated leachate was fed to the digester over the start-up phase that was completed in about 40 days. During the operational period, the organic load rate (OLR) changed between 4.25 kgCOD/m3d and 38.5 kgCOD/m3d. The chemical oxygen demand (COD) abatement was higher than 90% for OLR values up to 14.5 kgCOD/m3d and around to 80% for applied loads equal to 24.5 kgCOD/m3d. At this OLR, it was reached the maximum daily biogas production of about 9.3 Lbiogas/(Lreactord). The CH4 fraction was between 70%–78% and the methane production yield in the range 0.34–0.38 LCH4/gCODremoved. The deterioration of biogas production started for OLR values that were over the threshold of 24.5 kgCOD/m3d when a volatile fatty acids (VFA) accumulation occurred and the pH dropped below 6.5. The maximum ratio between VFA and alkalinity (ALK) tolerable in the CSTR was identified to be 0.5 gCH3COOH/gCaCO3. Through an economic analysis, it was proven that the digestion of compost leachate could ensure significant economic profits. Furthermore, the produced digestate had characteristics that were compatible for agricultural applications.

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“…Nitrate is one of the most widespread contaminants in surface water and groundwater, due to its high solubility and extensive use in many activities [1]. Nitrogen compounds are released into the environment by several sources, such as chemical fertilizers, pesticides, animal wastes, digestates and municipal and industrial wastewater [1][2][3][4][5][6]. Elevated concentrations of nitrate in water can lead to environmental and health issues.…”

Section: Introductionmentioning

confidence: 99%

Chemical Denitrification with Mg0 Particles in Column Systems

2020

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The removal of nitrate from aqueous environments through zero-valent metallic elements is an attractive technique that has gained increasing interest in recent years. In comparison to other metallic elements, zero-valent magnesium (ZVM) has numerous beneficial aspects. Nevertheless, the use of Mg0 particles for nitrate reduction in column systems has not been investigated yet. To overcome the lack of research, in the present study, a wide experimental activity was carried out to develop a chemical denitrification process through ZVM in batch column equipment. Several tests were executed to evaluate the effects of recirculation hydraulic velocity, pH, Mg0 amount, N-NO3− initial concentration and temperature on the process performance. The results show that the process efficiency is positively influenced by the recirculation velocity increase. In particular, the optimal condition was detected with a value of 1 m/min. The process pH was identified as the main operating parameter. At pH 3, abatements higher than 86.6% were reached for every initial nitrate concentration tested. In these conditions, nitrogen gas was detected as the main reaction product. The pH increase up to values of 5 and 7 caused a drastic denitrification decline with observed efficiencies below 26%. At pH 3, the ratio (RMN) between Mg0 and initial nitrate amount also plays a key role in the treatment performance. A characteristic value of about RMN = 0.333 gMg0/mgN-NO3− was found with which it is possible to reach the maximum reaction rate. Unexpectedly, the process was negatively affected by the increase in temperature from 20 to 40 °C. At 20 °C, the material showed satisfactory denitrification efficiencies in subsequent reuse cycles. With the optimal RMN ratio, removals up to 90% were detected by reusing the reactive material three times. By means of a kinetic analysis, a mathematical law able to describe the nitrate abatement curves was defined. Moreover, the relation between the observed kinetic constant and the operating parameters was recognized. Finally, the reaction pathways were proposed and the corrosion reaction products formed during the treatment were identified.

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Energetic Valorization of Wet Olive Mill Wastes through a Suitable Integrated Treatment: H2O2 with Lime and Anaerobic Digestion

Cited by 18 publications

References 42 publications

Biofuel Production and Phosphorus Recovery through an Integrated Treatment of Agro-Industrial Waste

Biofuel Production and Phosphorus Recovery through an Integrated Treatment of Agro-Industrial Waste

Biogas Generation through Anaerobic Digestion of Compost Leachate in Semi-Continuous Completely Stirred Tank Reactors

Chemical Denitrification with Mg0 Particles in Column Systems

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