Cost Model Development for Municipal Waste Water Treatment Plant Operations

V raziskavi smo analizirali vse vrste stroškov obratovanja čistilnih naprav za čiščenje odpadnih komunalnih vod (odslej ČN). Naš namen je bil, da ugotovimo vplivnost posameznih vrst stroškov na polno stroškovno ceno. Določili smo 5 vrst najpomembnejših stroškov, ki imajo največji vpliv na polno stroškovno ceno za storitve čiščenja odpadnih komunalnih vod. Izdelali smo poenostavljeni modelni izračun polne stroškovne cene obratovanja čistilne naprave. Ta poenostavljen stroškovni model lahko služi kot orodje upravljavcem ČN, saj neodvisno od tehnologije čiščenja omogoča dokaj natančen izračun polne stroškovne cene za storitve čiščenja odpadnih komunalnih vod. Za lažje razumevanje tehničnega vidika obratovanja čistilnih naprav smo najprej preučili postopke čiščenja in procese, ki se izvajajo. Pri tem smo spoznali, da gre pri obratovanju ČN v osnovi za tri faze čiščenja: primarna, sekundarna in terciarna. V nadaljevanju smo opisali vrste tehnologij čiščenja, ki se uporabljajo v sekundarni fazi. Pregledno smo v tabelah ponazorili posamezne vrste stroškov, ki nastajajo v posameznih fazah čiščenja odpadnih komunalnih vod in jih razvrstili glede na različne vrste tehnologij. Glede na spoznanje, da se je Slovenija kot članica Evropske unije obvezala, da svoja pravila in zakonska določila prilagaja strategijam skupne evropske politike, smo zato najprej pregledali vsebine teh določil evropske politike na področju varovanja vod. Osnovne vsebine določil izhajajo iz Okvirne direktive o vodah 2000/60/ES (WFD). Nadalje smo povzeli tista zakonska določila iz veljavnih aktov Slovenije, ki se nanašajo na oblikovanje cen za storitve čiščenja odpadnih komunalnih vod. Pomembni del našega raziskovalnega dela je bila anketa. Izvedli smo anketo v tistih komunalnih podjetjih v Sloveniji, ki upravljajo čistilne naprave za čiščenje odpadnih komunalnih vod. Tako smo dobili informacije o vrstah stroškov, o pomembnosti vpliva posameznih stroškov na vse stroške obratovanja čistilne naprave, o cenah (prodajnih in stroškovnih) za storitve čiščenja odpadnih komunalnih vod ter ostale splošne podatke. Iz podatkov v anketi smo prikazali primerjavo prodajnih in stroškovnih cen v letu 2015. Dokazali smo, s 95% verjetnostjo, da povprečno tri ključne vrste stroškov, tj. stroški električne energije, stroški dela, stroški mulja, skupaj določajo več kot 50% polne stroškovne cene storitev čiščenja odpadnih komunalnih vod. Predstavili smo nekatere usmeritve za optimizacijo stroškov obratovanja ČN, ki jih že uporabljajo na čistilnih napravah v Sloveniji. Gre za izrabo nastajajočega plina, ki nastaja kot stranski produkt pri razpadanju mulja v terciarni fazi in se lahko uporabi kot gorivo za generiranje električne energije. V Evropski uniji se zbirajo podatki o prodajnih cenah javnih storitev, tudi za čiščenje odpadnih komunalnih vod z namenom, da se vzpostavlja primerjava cen javnih storitev in se tako ugotavlja učinkovitost izvajanja v posameznih državah. Na osnovi tega spoznanja smo podali predlog, naj se Slovenija vključi v takšno primerjalno oceno.During our research we analysed different types of operating costs at wastewater treatment plants. Our goal was to establish the influence of individual costs on full cost pricing. We defined 5 types of most important costs that have the greatest impact on full cost pricing of municipal wastewater treatment. We established a simplified calculation model of full cost pricing for wastewater treatment plant (WWTP) operation. This simplified cost model can serve as a tool for WWTP operators since it enables a fairly accurate calculation of full cost price for municipal wastewater treatment independent of treatment technology. To facilitate understanding of the technical aspect of wastewater treatment plants\u27 operation, we first examined the treatment procedures and processes to be carried out. By doing so, we realized that the operation of municipal WWTP basically consists of three phases: primary, secondary and tertiary. We described the types of cleaning technologies, which are used in the secondary phase. In various tables we transparently illustrated different types of costs in individual phases of treatment and classified them according to different types of technologies. Noting that Slovenia, as a member of the European Union, committed itself to adapt its rules and legal provisions to the strategies of common European policy, we therefore first examined the contents of these terms of European policy from the field of water protection. Basic content of the provisions is arising from the Water Framework Directive 2000/60/ EC. Furthermore, we summarized those statutory provisions from the existing Slovenian acts, which relate to the pricing of municipal WWTP services as our primary topic of research. An important part of our research was the survey. We carried it out in those municipal companies in Slovenia, which are operators of WWTP for municipal wastewaters. By performing a survey we obtained the information about the types of costs, the significance of influence of the individual costs on all the operating costs of WWTP operation, the prices (sales and costs) of municipal WWTP services as well as other general information. From the data in the survey we presented a comparison of sales and input prices in 2015. We showed with 95% probability that in average three main types of costs, ie. electricity costs, labor costs and costs of sludge, jointly determine more than 50% of the full cost price of municipal wastewater treatment costs. We presented some guidelines for optimizing the operating costs of the WWTP, which are already used in the treatment plants in Slovenia. It is the exploitation of the emerging gas, which is produced as a byproduct of the decomposition of the sludge in the tertiary stage and can be used as a fuel for generating electricity. The European Union is gathering information on the selling prices of public services for the treatment of municipal waste waters in order to establish a price comparison of public services to determine the effectiveness of implementation in the respective countries. Based on this knowledge, we made a proposal to include Slovenia in such benchmarking