Potential of Sustainable Concept for Handling Organic Waste in Tunisia

Nour El Houda Chaher,Moktar Hamdi,Qahtan Thabit,Abdallah Nassour,Michael Nelles,Safwat Hemidat,Mehrez Chakchouk

doi:10.3390/su12198167

Abstract

Nowadays, Tunisia is seeking to implement cost-efficient and sustainable solutions in relation to the treatment of organic waste which, at up to 65%, makes up the largest proportion of total waste generated in the country. Therefore, an efficient tool for decision makers is needed to provide a clear approach about the potential of organic waste as well as the treatment concept, which can be adapted based on technical requirements and local conditions. Results revealed that there is a high variation in terms of the nature of the collected biowaste, which affects the selection of the adopted bioprocess for each geographical zone of the study area. Three main categories of biowaste are produced along the coastline of Tunisia: food waste (FW) (102.543 t/a); green waste (GW) (1.326.930 t/a); and cattle manure (CM) (1.548.350 t/a). Based on the results of similar projects and laboratory-scale research work, anaerobic and aerobic digestion were examined. Regarding aerobic digestion, the monitoring of several physicochemical parameters ascertained that the co-composting of FW and GW at different ratios (GW: FW = 100:0, 75:25, 50:50, and 25:75) allowed the production of a stable and mature compost. A highly qualified end-product was generated from each trial categorized as a finished compost of class V with reference to German Standards of compost. Regarding the anaerobic process, different feedstock mixtures (FW:CM = 0:1, 1:1, 2:1, and 3:1) were prepared to feed semi-continuous anaerobic reactors. However, a significant improvement in the process development was recorded for digesters including a higher fraction of FW, which produced 0.846 LN/kg VSin as the maximum biogas production. Therefore, biological treatments of food waste and different co-substrates seems to be a suitable technique for Tunisia in terms of waste management, environmental, and energy aspects. However, the evaluation of the efficiency of the proposed biological treatments was also verified by a draw-up of a technical and economic feasibility analysis. Although the cost–benefit estimations proved that the profits from both the compost and biogas plants would be very modest, the feasibility of such sustainable projects should not only be evaluated on an economic basis, but also by taking into account socio-environmental considerations including decreasing environmental threats, providing work opportunities, increasing incomes, stimulating public awareness as well as reducing the operating costs linked to landfilling.

Highlights

In light of population growth, the rapid rate of urbanization and industrialization as well as the changes in consumption patterns with higher standards of living, the production of waste, which is undesirable but unavoidable, by-products is increasingly important, making the creation of an efficient solid waste management strategy (SWMS) a worldwide challenge
Biowaste generated from the urban sector was restricted to food and green waste collected from citizen services providers such as hospitals and clinics, the hospitality and commercial sectors as well as green residue gathered from parks
This research is an attempt to provide an efficient tool for decision-makers by providing a potential organic waste treatment concept that can be adapted based on technical requirements and local conditions in Tunisia

Summary

Introduction

In light of population growth, the rapid rate of urbanization and industrialization as well as the changes in consumption patterns with higher standards of living, the production of waste, which is undesirable but unavoidable, by-products is increasingly important, making the creation of an efficient solid waste management strategy (SWMS) a worldwide challenge. The unsustainable treatment of municipal, agricultural, and industrial solid waste is an alarming issue, which puts extra pressure on the environment as well as on human health [1]. A global snapshot of solid waste management to 2050 illustrates that SWMS issues concerns developing countries, and some developed ones [4]. Tunisia is facing numerous issues including human health, environmental, and sociopolitical threats, pushing the decision makers to improve solid waste management (SWM) schemes into more integrated approaches in recent years [5]. Located in North Africa, Tunisia covers an area of about 163.610 km. Located in North Africa, Tunisia covers an area of about 163.610 km2 It is divided into 24 goveLrnoocarateteds,ingrNouoprtehdAinfrtichae, NTuonrtihsieaascto, vNeorsrtahnwaesret,aMoifdaebaostu,tM16id3w.61es0t,kSmo2u.thIetaisst dainvdidSeoduitnhtwoe2s4t, gaonvderinncoorrapteosr,agtersoumpoerde itnhathne2N70ormthuenaiscti,pNaloitritehswoerstu, rMbaidneaagstg,loMmiderwaetisotn, sS.oTuhtheeatosttaalnpdopSouulatthiownesotf, aTnudniisniacoirsp1o1r,a7t2e2s,0m38orweitthhaanro2u7n0dm7u0n%icoipf athlietimesboerinugrbcaonncaegngtrloamtederoantiotnhse.

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