An overview of waste composts produced in Estonia

Erinevast lähtematerjalist ja erineva tehnoloogiaga toodetud kompostidele optimaalsete rakenduste leidmiseks põllumajanduses on oluline hinnata kompostide omadusi keemiliste analüüside ja taimekasvatuslike tulemuste põhjal. Antud töö eesmärgiks oli anda ülevaade Eestis toodetavate kompostide omadustest ja võrrelda neid Euroopa Kompostimisvõrgustiku (ECN) juhendmaterjali nõuetega. Kompostide võrdlemiseks saadi andmed keemiliste analüüside ja taimkatsete tulemusel. Keemiliste analüüsidega määrati taimetoitainetesisaldus (Ntot, Ptot, Ktot, S, pH, Corg) ja raskmetallide sisaldus (Zn, Cu, Ni, Cd, Cr, Pb). Taimetoitainesisaldus kompostides oli üsna erinev. Reoveesete sisaldab taimedele olulisi ühendeid, milleks on fosfor, lämmastik ja kaalium. Seetõttu oli oodatult rohkem fosforit ja lämmastikku kuues reoveesettekompostis. AS Kuressaare, AS Uikala ja AS Ragn-Sells’i kompostidel oli fosfori ja lämmastiku sisaldus siiski eeldatust madalam. Biolagunevate jäätmete kompostides ja sõnnikukompostides oli toitainetesisaldus hea. Võrreldes reoveesettekompostidega oli eelmainitud kompostide kaaliumisisaldus tunduvalt suurem. Madal pH oli probleemiks kahes kompostis (AS Põlva Vesi ja AS Valio Eesti). Idanemist arvestati seitse päeva pärast seemnete külvi, 50% komposti ja mulla segu ning 100% komposti puhul. Biolagunevate jäätmete kompostide idanemine oli soodne nii 50% kui ka 100% kompostiseguga. Vaid ühe komposti puhul oli idanemine madal. Sõnnikukompostidest oli hea idanemine Tallinna Loomaaia kompostiga. Reoveesettekompostide idanemine oli väga soodne. Idanemine oli ka nendel kompostidel hea, kus lämmastikku ja fosforit oli eeldatust vähem. Umbrohuseemneid oli üle lubatud koguse viies kompostis. Umbrohuseemneid oli rohkem biolagunevate jäätmete kompostides. Raskmetallidega oli probleeme seitsmes kompostis. Kõikide raskmetallide lubatud määra ületas Ecocleaner Sillamäe MBT kompost, mis oli etteaimatav, kuna komposti lähteaineteks on sortimata olmejäätmed, mis sisaldavad rohkelt raskmetalle. Reoveesettekompostidest ületas raskmetallide sisalduse vaid kaks komposti, milleks olid AS Tallinna Vesi ja AS Epler&Lorenz kompostid. Mõlemal oli lubatust suurem vase ja kaadmiumi hulk. AS Epler&Lorenz’i kompost ületas ka tsingi ja plii lubatud määra. Sõnnikukompostidest ületas lubatud vasesisalduse ühe ettevõtte kompost, milleks oli Virve Hobusekasvatus. Biolagunevate jäätmete kompostidest ületasid kolme prügila kompostid lubatud tsingisisalduse. Uuring andis komplekse ülevaate Eestis toodetavatest kompostide keemilistest omadustest ja sobivusest idanemiskeskkonnana ning tõi välja nende erinevused. Edasised uuringud on vajalikud, et hinnata komposte täpsemate keemiliste analüüsidega ja selgitada kompostide kasutusotstarve ning kasutusnormid.In order to find the optimal application in agriculture to composts produced from different primary materials and with different production technologies, it is important to assess the properties of compost, based on the results of chemical analysis and plant growing. The purpose of this bachelor’s thesis is to provide an overview of the properties of composts produced in Estonia and to compare these to the requirements of the guidance materials of the European Compost Network. Chemical analyses and plant tests provided the results for the comparison of composts. Plant nutrient content (Ntot, Ptot, Ktot, S, pH, C) and heavy metal content (Zn, Cu, Ni, Cd, Cr, Pb) were determined by chemical analyses. Plant nutrient content in composts was rather different. Wastewater sediment contains essential compounds for plants, such as phosphorus, nitrogen and potassium. Therefore, as expected, more phosphorus and nitrogen was found in six wastewater sediment composts. The content of phosphorus and nitrogen in the composts of AS Kuressaare, AS Uikala and AS Ragn-Sells were smaller than expected. Nutrient content of biodegradable waste composts and manure composts were good. Compared to wastewater sediment composts, the potassium level of the previously mentioned composts was considerably higher. Low level of PH proved to be a problem in two composts (AS Põlva Vesi and AS Valio Eesti). Germination was calculated seven days after seeding in the case of 50% compost and soil mixture and 100% compost. The germination of biodegradable waste composts was advantageous in the case of both 50% and 100% composts. Only in one case the germination was low. Among manure composts, the compost of Tallinna Loomaaed proved to have good germination properties. Germination of wastewater sediment composts was very favourable. Germination also proved to be good among composts where the levels of nitrogen and phosphorus were less than expected. Five composts exceeded the amount of weed seeds allowed in compost. The most weed seeds were found in biodegradable waste composts. Seven composts had problems with heavy metals. All the authorized levels of heavy metals were exceeded by Ecocleaner Sillamäe MBT compost, which was predictable, because the primary material of this compost is unsorted municipal waste, rich in heavy metals. Among wastewater sediment composts, the level of heavy metals was exceeded by only two compost, these were the composts of AS Tallinna Vesi and AS Epler&Lorenz. In both cases, the levels of copper and cadmium were higher than authorized. The compost of AS Epler&Lorenz also exceeded the authorized limit of zinc and lead. Among manure composts, the compost of Virve Hobusekasvatus was the one compost that exceeded the authorized level of copper. The authorized zinc level was exceeded by the composts of three landfills. This study gave a complete overview of the chemical properties and suitability as germination environment of composts in Estonia and brought out their differences. Future studies are necessary to evaluate composts with more precise chemical analyses and ascertain the uses and standards of composts