Razvoj holističkog modela za prioritizaciju deponija za sanaciju i/ili zatvaranje na osnovu procene uticaja na životnu sredinu

Abstract

Deponije komunalnog otpada predstavljaju važan i neizostavan element integrisanog upravljanja otpadom, ujedno predstavljajući, naročito tokom aktivnog perioda rada, gotovo neiscrpan izvor emisije zagađujućih materija u životnu sredinu. Ovaj je negativan uticaj najizraženiji kod deponija koje ne ispunjavaju osnove uslove definisane nacionalnim i međunarodnim regulativama. Države u razvoju, poput Republike Srbije, suočene su sa najizraženijim problemima neadekvatnog upravljanja otpadom, kao rezultat ograničenog budžeta za komunalne delatnosti, nedostatka razumevanja problema i nedovoljno dostupnih podataka, zbog čega se sanacija i zatvaranje nesanitarnih deponija po pravilu vrši na nesistematski način. Vodeći se holističkim pristupom, prvo je neophodno sagledati faktore koji doprinose zagađenju životne sredine, pri čemu veliki broj nesanitarnih deponija i faktora od značaja, postupak evaluacije deponija sa aspekta uticaja na životnu sredinu predstavlja kompleksan proces, gde primena MCDM pokazuje veliki potencijal. S tim u vezi, izvršena su opsežna ispitivanja u cilju utvrđivanja uticaja pet odabranih deponija komunalnog otpada različitih karakteristika na stanje životne sredine, i na osnovu rezultata je izvršeno definisanje dve različite MCDM korišćene za prioritizaciju deponija u odnosu na rizik koje oni predstavljaju sa aspekta uticaja na životnu sredinu: SAW FUCOM i EVIAVE. Odabrane model alternative, odnosno deponije komunalnog otpada (G, M, Z, SM i S), koju su po svojim karakteristikama dovoljno različite za potrebe određivanja performansi korišćenih MCDM modela. Deponija Z nije prethodno imala uslove uzorkovanja podzemne vode, a za te potrebe izvršeno je postavljanje brzih, pametnih pijezometara tehnikom utiskivanja konusa. Kako kriterijumi i pod-kriterijumi MCDM modela predstavljaju parametre po kojima se mere performanse odabranih modela u odnosu na procenu uticaja ispitivanih deponija na životnu sredinu, njihov odabir je izvršen u skladu sa ciljevima i kontekstom MCDM modela, dostupnosti relevantnih podataka u odnosu na opravdanost njihove upotrebe, mogućnostima njihove primene na veći broj deponija i opštim zahtevima MCDM. Odabrano je ukupno 21, odnosno 23 pod-kriterijuma uzimajući u obzir i pod-kriterijume koji opisuju realno stanje kvaliteta podzemne vode i zemljišta na ispitivanim deponijama (Kvalitet podzemne vode i Kvalitet zemljišta), čije su vrednosti određene računanjem Nemerow-og indeksa (NPI). Za EVIAVE model korišćene su predefinisane vrednosti težinskih faktora, dok je za SAW-FUCOM model korišćena FUCOM metoda definisanja težinskih faktora učešćem pet donosioca odluka. Kroz pet koraka FUCOM algoritma donosioci odluka su dodelili najveći značaj tehničko-tehnološkim I operativnim pod-kriterijumima deponija, određujući tako prioritet izvoru zagađenja u sistemu izvor-put dospevanja-receptor. Monitoring kvaliteta podzemne vode ispitivanih deponija obuhvatio je uzorkovanje podzemne vode u periodu od 2015. do 2019. godine, i analizu širokog opsega parametara, od kojih su se prema njihovim vrednostima ili Pearsonovim koeficijentima korelacije relevantnim pokazali Fe, Mn, Zn, Cd, Cu, Ni, Cr, As i ∑PAH16. Kvalitet zemljišta na teritoriji ispitivanih deponija određen je monitoringom u period od 2016. do 2019. godine, pri čemu su, kao u slučaju podzemne vode, takođe dobijene visoke vrednosti standardnih devijacija ispitivanih parametara (Ni, Zn, Cd, Cr, Cu, Pb, As, Hg, ∑PAH16 I mineralna ulja) potvrđujući time potrebu za analizom kvaliteta zemljišta i podzemne vode tokom perioda visokog i niskog vodostaja. Prethodno navedeni ispitivani parametri kvaliteta zemljišta su se svi, svojim povećanim sadržajem ili korelacijom određenom Pearsonovim koeficijentom korelacije, pokazali relevantnim NPI model parametrima. Opravdanost upotrebe monitoringom dobijenih rezultata kvaliteta podzemne vode i zemljišta određena je analizom odnosa stepena potrebne kompleksnosti modela u odnosu na njihovu pouzdanost tokom evaluacije ispitivanih deponija prema njihovom uticaju na životnu sredinu kroz dve izvedbe SAW-FUCOM i EVIAVE modela: integrisani (sa upotrebom monitoringom dobijenih rezultata) i probabilistički (bez upotrebe monitoringom dobijenih rezultata). Analizom osetljivosti multi-kriterijumske prioritizacije ispitivanih deponija, i jednostavnim poređenjem dobijenih ocena deponija zaključeno je da sve konačne ocene deponije S ukazuju na najveći prioritet u odnosu na ostale ispitivane deponije, što čini deponiju S jedinu jednako rangiranu primenom MCDM modela. Rezultati SAW-FUCOM i EVIAVE rangiranja pokazuju najveće razlike za deponije Z i SM, pri čemu je deponija SM rangirana kao druga po prioritetu za sanaciju i/ili zatvaranje SAW-FUCOM modelom, dok je EVIAVE modelom rangirana kao treća (i obrnuto za deponiju Z). Različito rangiranje ovih deponija rezultat je drugačijeg pristupa korišćenju pod-kriterijuma MCDM modela, naročito u domenu uticaja na zemljište. Generalno veće ocene ispitivanih deponija dobijene su SAW-FUCOM modelom, što ukazuje na različitost primenjenih MCDM modela i njihovog ophođenja prema vrednostima odabranih pod-kriterijuma. Razlike ocena ispitivanih deponija SAW-FUCOMI i SAW-FUCOMP modela pokazuje veće varijacije u vezi sa kompleksnošću deponije, dok su razlike ocean dobijene EVIAVEI i EVIAVEP modela u funkciji različitosti uticaja deponija na zemljište. Obe izvedbe SAW-FUCOM modela daju jednake zaključke u pogledu prioriteta ispitivanih deponija za sanaciju i/ili zatvaranje, što nije slučaj za EVIAVE model. U tom smislu, SAW-FUCOM model pokazuje manju osetljivost, i time veću pouzdanost njegove primene. Posredstvom dva scenarija, odnosno dve izvedbe (integrisane i probabilističke) SAW-FUCOM modela formirane su liste prioriteta ispitivanih deponija koje jednako rangiraju ove deponije. Detaljnom analizom dobijenih ocena ispitivanih deponija zaključuje se da integrisanje rezultata monitoringa kvaliteta podzemne vode i zemljišta pod uticajem deponije ne pravi suštinske razlike u ocenjivanju deponija, ne iskazujući dovoljno opravdanosti, odnosno neophodnosti uključivanja ovako dobijenih podataka. Na osnovu liste prioriteta za zatvaranje/sanaciju deponija komunalnog otpada formirane SAW FUCOM modelom stvoriće se preduslovi za bolje planiranje i obezbeđivanje potrebnih sredstava za aktivnosti zatvaranja i sanacije, istovremeno pomažući nadležnim institucijama i komunalnim preduzećima da vrše dobro osnovane odluke o prioritizaciji deponija za sanaciju i/ili zatvaranje na osnovu uticaja na životnu sredinu i zdravlje ljudi.

Municipal solid waste landfills represent an important and essential element of integrated waste management, at the same time representing an almost inexhaustible source of environmental pollution, especially during active period. This negative impact is most intensive at landfills that do not meet the basic requirements defined by national and international regulations. For developing countries, such as the Republic of Serbia, the risks of inadequate waste management are even greater as a result of a limited budget for communal activities, a lack of understanding of the problem and insufficiently available data, which is why the rehabilitation and/or closure of unsanitary landfills is usually carried out in an unsystematic way. Guided by a holistic approach, it is first necessary to look at the factors that contribute to environmental pollution, taking into account large number of unsanitary landfills and important factors, making evaluation procedure of landfills from the aspect of environmental impact a complex process, where the application of MCDM shows great potential. In this regard, a great effort was put into determination of the environmental impact of five selected municipal solid waste landfills with different characteristics, and based on the results two different MCDM models were developed, that were ultimately used for prioritizing landfills in relation to the environmental risk they represent: SAW-FUCOM and EVIAVE. The selected model alternatives, i.e., municipal solid waste landfills (G, M, Z, SM and S), are sufficiently different in their characteristics for the purposes of determining the performance of used MCDM models. Landfill Z did not previously have conditions for groundwater sampling, and for those needs, quick, smart piezometers were installed using the cone impression technique. As the criteria and sub-criteria of the MCDM model represent the parameters by which the performance of the selected models is measured in relation to the environmental impact assessment of the investigated municipal solid waste landfills, their selection was made in accordance with the objectives and context of the MCDM model, the availability of relevant data in relation to the justification for their use, the possibilities of their application to a larger number of landfills and the general requirements of MCDM. A total of 21, and ultimately 23 sub-criteria were selected, taking into account the sub-criteria that describe the quality of investigated groundwater and soil under the influence of investigated landfills (groundwater quality and soil quality), whose values were determined by calculating the Nemerow index (NPI). For the EVIAVE model, predefined values of weighting factors were used, while for the SAW FUCOM model, the FUCOM method of defining weighting factors was used with the participation of five decision makers. Through the five levels of the FUCOM algorithm, decision-makers assigned the greatest importance to the technical-technological and operational sub criteria of landfills, thus indicating the priority of the pollution source in the source-pathway-receptor system. The groundwater quality monitoring of the investigated landfills included groundwater sampling in the period from 2015 to 2019, and the analysis of a wide range of parameters, of which the most relevant, according to their values or Pearson's correlation coefficients, are Fe, Mn, Zn, Cd, Cu, Ni, Cr, As and ∑PAH16. The quality of the soil in the territory of the investigated landfills was determined by monitoring in the period from 2016 to 2019, where, similar to groundwater, high values of standard deviations of the analyzed parameters were also obtained (Ni, Zn, Cd, Cr, Cu, Pb, As, Hg, ∑PAH16 and mineral oils), thus confirming the need for soil and groundwater quality analysis during periods of high and low water levels. All of the previously mentioned analyzed soil quality parameters, with their increased content or correlation determined by the Pearson correlation coefficients, proved to be relevant NPI model parameters. The justification for the use of the results obtained by groundwater and soil quality monitoring was determined by analyzing the relationship between the degree of MCDM model complexity and their consistency during the evaluation of the investigated landfills, according to their environmental impact using two modifications of the SAW-FUCOM and EVIAVE models: integrated (includes results obtained by monitoring) and probabilistic (without using monitoring results). By analyzing the sensitivity of the multi-criteria prioritization of the investigated landfills, and by simply comparing the obtained investigated landfills grades, it was concluded that all the final grades of landfill S indicate the highest priority compared to the other investigated landfills, which makes landfill S the only one equally ranked using the MCDM models. The results of SAW-FUCOM and EVIAVE ranking show the biggest variances for landfills Z and SM, where landfill SM is ranked with the second priority for closure and remediation by the SAW-FUCOM model, while it is ranked third by the EVIAVE model (and vice versa for landfill Z). The different ranking of these landfills is the result of a different approach of using sub-criteria of the MCDM models, especially in the domain of impact on the soil quality. Generally, higher grades of the investigated landfills were obtained with the SAW-FUCOM model, which indicates the diversity of the applied MCDM models and their design in correlation to sub-criteria usage. The differences in ratings of the investigated municipal solid waste landfills of the SAW-FUCOMI and SAW-FUCOMP models show greater variations in relation to the complexity of the landfills, while the differences in ratings obtained by the EVIAVEI and EVIAVEP models are in a function of the differences in the impact of landfills on soil quality. Both versions of the SAW-FUCOM model gave the same conclusions regarding the priority of the investigated landfills for closure and remediation, which is not the case for the EVIAVE model. Therefore, the SAW-FUCOM model shows a lower sensitivity, and thus a higher reliability of its application. By means of two scenarios, i.e., two modified (integrated and probabilistic) implementations of the SAW-FUCOM model, investigated landfills priority lists were formed, which rank these landfills equally using both versions of SAW-FUCOM. By means of comprehensive analysis of the obtained investigated municipal solid waste landfills grades, it is concluded that the integration of the results obtained by monitoring of the quality of groundwater and soil under the influence of the landfill does not make essential differences in the evaluation of investigated landfills, not showing enough justification, that is, the necessity of including the data obtained in this way. Based on the list of priorities for the remediation/closure of municipal solid waste landfills obtained by the SAW-FUCOM model, preconditions will be created for better planning and provision of the necessary funds for closure and remediation activities, at the same time helping organizations and utility companies to make well-founded decisions on prioritizing landfills for remediation and/or closure based on environmental and human health impact assessment.