Combination of air stripping and biological processes for landfill leachate treatment

Landfill waste decomposition generates a dark effluent named, leachate which is characterized by high organic matter content. To minimize these polluting effects, it becomes necessary to develop an effective landfill leachate treatment process. The objective of this study was to evaluate the performance of an innovative approach based on air stripping, anaerobic digestion (AD) and aerobic activated sludge treatment. A reduction of 80% of ammonia and an increase of carbon to nitrogen ratio to 25 were obtained, which is a suitable ratio for AD. This latter AD was performed in fixed bed reactor with progressive loading rate that reached 2 and 3.2 g COD/L/d for the raw and diluted leachate (1:2), respectively. The anaerobic treatment led to significant removal of chemical oxygen demand (COD) and biogas production, especially for the diluted leachate. The COD removal was of 78% for the raw leachate and a biogas production of 4 L/d with 70% methane content. The use of the diluted leachate led to 81% of COD removal and 7 L/d biogas with 75% methane content. It allowed a removal of 77% COD and more than 97% of the organic compounds present in the initial leachate sampl

Déchets du centre d’enfouissement technique de Sfax (Tunisie) : nature, composition et traitement

Landfilling is the strategy adopted in Tunisia to ensure sustainable solid waste management. The Sfax controlled landfill is one of the technical landfills that have been set up. This study presents the main categories and characteristics of household waste buried in the Sfax controlled landfill, as well as the physic-chemical and micro-biological properties of the generated leachates. The leachates treatment processes applied at the station level are presented and their performance is discussed. The results of the waste characterization show the dominance of the potentially biodegradable fermentable fraction (69%). The distribution by particle size of the waste shows a dominance of the average fraction whose particle size is between 20 and 100mm. The characterization of leachates generated shows the presence of a high organic load that is difficult to biodegrade, a high content of ammoniacal nitrogen and recalcitrant compounds such as phenols. We also note the presence of some micro-pollutants minerals and certain pathogens. The toxic nature of leachates has been demonstrated by microtoxicity and phytotoxicity tests. The monitoring of the operation of the leachates treatment plant shows a significant variability of the quantities treated, which explains the filling of the storage ponds.La mise en décharge est le mode de gestion adoptée en Tunisie pour assurer une gestion des déchets solides. Le centre d’enfouissement technique (CET) de la région de Sfax constitue l’un des principaux centres qui ont été mis en place en Tunisie depuis 2009. L’objectif de ce travail est d’identifier les principales catégories et caractéristiques des déchets ménagers enfouis dans le CET de Sfax, ainsi que les propriétés physico-chimiques et microbiologiques des lixiviats générés. Dans ce travail, les procédés de traitement appliqués aux lixiviats du CET de Sfax ont également été présentés et évalués.Les résultats de la caractérisation des déchets montrent la prédominance de la fraction fermentescible potentiellement biodégradable (69 %). La répartition granulométrique des déchets montre une prépondérance de la fraction moyenne dont la granulométrie est comprise entre 20 et 100 mm. La caractérisation des lixiviats générés montre la présence d’une forte charge organique difficilement biodégradable, une forte teneur en azote ammoniacal et en composés récalcitrants tels que les phénols. On note également la présence de quelques micropolluants minéraux et de certains germes pathogènes. Le caractère toxique des lixiviats a été démontré à travers les tests de microtoxicité et de phytotoxicité. Les fluctuations de débit et de charge sont responsables des perturbations observées dans le fonctionnement de la station

Identification des indicateurs de stabilisation des déchets solides urbains et validation sur un site de PTMB français, pour une application en Tunisie

Le prétraitement mécanique et biologique des déchets ménagers avant enfouissement représente une alternative intéressante à l enfouissement brut des déchets. Des études ont montré plusieurs avantages liés à l application de cette technique, - les déchets enfouis sont en partie stabilisés, -les impacts, lixiviat et biogaz, sont moins importants sur l environnement, et -la phase de post exploitation en général 30 ans pour les décharges conventionnelles, pourrait être réduite. L objectif de la thèse est de déterminer les principaux indicateurs de stabilisation des déchets ménagers en cours d un procédé de prétraitement mécano-biologique aérobie. Les indicateurs cités dans la littérature sont multiples mais leur pertinence dans le cadre d un suivi d une unité de PTMB n a pas été confirmée. Ainsi, dans un premier temps, ces indicateurs ont été appliqués dans le cadre du suivi d une unité industrielle de PTMB en France pour valider et optimiser les protocoles décrits dans la littérature scientifique. Dans un deuxième temps, une pré-étude de faisabilité de ce type de procédé a été réalisée en Tunisie, à la suite de campagnes de caractérisation hivernales et estivales des déchets générés dans quatre villes. Les résultats à l issu de cette pré-étude ont confirmé le caractère fermentescible des déchets tunisiens mais avec un taux inférieur à celui déterminé lors de la campagne nationale de 1996. Le suivi de la stabilisation des déchets mis en andains sur une plate-forme pilote a permis d appliquer les indicateurs de stabilisation les plus pertinents notamment les caractérisations de type MODECOM, les tests de lixiviation, le fractionnement des composés organiques selon le caractère hydrophobe et les tests biologiques (AT4 et BMP). Les indicateurs de stabilisation identifiés montrent des corrélations correctes. L ensemble des résultats obtenus corroborent ceux déduits du suivi de l unité industrielle qui montrent une défaillance du procédé appliqué vis-à-vis des normes en vigueur pour l acceptation des déchets en centre de stockage. L état de stabilisation n est pas encore atteint au bout de 4 mois de prétraitement aérobie, ce qui nécessitera d accroître les performances du procédé notamment par une prolongation de la durée du prétraitement notamment la fermentation et par l amélioration des conditions d aération.Mechanical pretreatment and biological waste before landfilling is an interesting alternative to the conventional landfilling. Several studies have shown benefits of the application of this technique - landfilled waste are partly stabilized, leachate and biogas impacts are less important, and post-operational phase typically 30 years for conventional landfills could be reduced. The aim of the thesis is to identify key indicators of household waste stabilization during an aerobic mechanical-biological pretreatment process. Indicators cited in the literature are numerous, but their relevance in the context of a monitoring unit PTMB has not been confirmed. Thus, in a first step, these indicators have been applied in the monitoring of an industrial unit in France PTMB to validate and optimize the protocols described in the literature. In a second step, a pre-feasibility study of this type of process has been carried out in Tunisia, after winter and summer waste characterization campaigns in four cities. The results of this preliminary study have confirmed the fermentable character of the Tunisian waste but with a lower rate than that determined in the national campaign of 1996. Monitoring of waste stabilization swathed on an experimental platform has allowed applying the most relevant waste stabilization indicators such as the MODECOM characterizations, the leaching tests, the fractionation of organic compounds by hydrophobicity and the respirometric tests (AT4 and BMP). Stabilization indicators identified show correct correlations. The overall results are consistent with those derived from the monitoring of industrial unit which show a failure of the applied process vis-à-vis the standards for the acceptance of waste at landfills. The state stabilization is not reached after 4 months of aerobic pretreatment, which will require the optimization of the process performance including an extension of the duration of the pretreatment, especially, the fermentation phase and the improvement of the ventilation conditions.LIMOGES-BU Sciences (870852109) / SudocSudocFranceTogoFRT

Application of sheep manure and potassium fertilizer to contaminated soil and its effect on zinc, cadmium and lead accumulation by alfalfa plants

In Jebel Ressas mining area (Southern of Tunisia), the dispersion of particles that contain Pb, Zn and Cd results in the contamination of the surrounding agricultural soils. These soils have high concentrations of Pb (970 mg kg−1), Zn (9641 mg kg−1) and Cd (53 mg kg−1). This glasshouse study examined the effect of application of fertilizers, i.e., organic fertilizer as local sheep manure and inorganic fertilizer as potassium chloride (KCl), on the growth, uptake and translocation of Cd, Pb, and Zn of alfalfa (Medicago sativa L.) grown on a contaminated soil. Obtained results showed that alfalfa could tolerate high Cd, Pb, and Zn concentrations in soil and had very good growth performance. Regarding to biomass generation it was observed, in every case, that plant growth is not affected in the treated soil compared with blanks sown in an untreated control soil; improvement ranged from 80% for the KCl to 97% for sheep manure. Application of sheep manure increased electrical conductivity and reduced DTPA-extractable metal concentrations in the soils. But KCl fertilizer favored their accumulation in plants. So, KCl could be a useful amendment for phytoextraction of metals by accumulator species, while sheep manure can be very useful for phytostabilisation

Evaluation of influence of coagulation/flocculation and Fenton oxidation with iron on landfill leachate treatment

Landfill leachates (LFL) collected from Sfax (Tunisia) discharge area are characterized by high chemical oxygen demand (COD), ammonium and salts contents. They constitute a source of phytotoxicity and pollution for ground water and surface water resources which requires an adequate treatment process. To evaluate the efficiency of the coagulation/flocculation treatment, special attention was paid to the effect of pH, coagulant and flocculant doses. Then, effect of zero valent iron was also studied alone and in combination with coagulation/flocculation pretreatment. Our results indicate high removal efficiencies by coagulation/flocculation (46% COD and 63% turbidity) and Fenton process (48% COD and 76% turbidity). The combined application of coagulation/flocculation and Fenton revealed higher COD removal (62%) and turbidity reduction (90%). These results showed the applicability of this combined treatment method for the degradation of organic compounds and reduction of the treated leachate toxicity

Carbon and nitrogen balances and CO2 emission after exogenous organic matter application in arid soil

Addition of organic amendments (OAs) could be a means to sequester carbon (C) in soils. However, the efficiency of C sequestration depends on how OAs evolve in the soil. A field study was installed in arid soil to which was added one of five OAs – olive husk-based compost (CM), palm leaf-based compost (CP), crushed olive pruning (GW), fresh olive mill wastewater (OMW) or fermented ovine manure (OM) – at an equivalent fixed level of 350 g of C/m2. C and N mineralization were followed for 112 days by measuring the evolution of released CO2 and mineral N evolution. The results showed that CM and CP did not disturb soil respiration, with a very low CO2 emission or almost no respiration for the CM, while CO2 release reached 7.6 g of CO2/m2 for GW and OMW. Soil organic carbon (SOC) was sustainably improved by 0.54% and 0.50%, respectively, for CM and CP. N mineralization showed no significant difference between amended and untreated soils. Based on these results, compost amendment was the most efficient for C sequestration to enhance soil fertility and consequently reduce the rate of CO2 emission

Persistence of pyrethroid Deltamethrin and its effects on extra virgin olive oil quality

Abstract: The use of pesticides in developing countries remains out of control in major cases. Consequently, it is common to find amounts of residues exceeding the Maximum Residue Limits (MRL