The use of the energy crop miscanthus giganteus for purification of nutrient-rich wastewater in scattered settlements

Za Slovenijo sta značilni razdrobljena poselitev in intenzivna kmetijska proizvodnja, ki je najbolj razvita na območjih, kjer so največje zaloge podtalnice. Reševanje odvodne vode in čiščenje odpadnih voda manjših naselji sta prednostni nalogi Slovenije. Ob tem si mora Slovenija zagotoviti najmanj 20 odstotni delež energije iz OVE ‒ obnovljivih virov energije (Direktiva EU o spodbujanju uporabe OVE). Namen naše naloge je bil ugotoviti, ali je mogoče očiščenje odpadnih voda v manjših naseljih s pomočjo energetske rastline prstastega trstikovca oz. miskantusa (Miscanthus x giganteus), ki bi imel hkrati dobre fitoremediacijske sposobnosti. Tako bi v nasadih miskantusa umetna gnojila nadomestili z odpadnimi viri, kar se kaže kot obetavna možnost znižanja pridelovalnih stroškov in hkratno zmanjšanje stroškov vloženih v čistilni proces odpadnega vira. Miskantus smo leta 2014 zasadili na štirih vzorčnih enotah. Enota 1: po potrebi smo rastline dognojevali z umetnimi gnojili, enota 2: po potrebi smo jih zalivali z odpadno vodo, enota 3: po potrebi smo jih zalivali z deževnico, enota 4: rastline smo izpostavili naravnim pogojem, brez dodajanja kakršnih koli gnojil ali tekočin. Leto dni kasneje, v drugi rastni sezoni smo dvakrat na mesec (vsakih 10 dni) spremljali različne rastne parametre, fotokemično učinkovitost fotosistema II, vsebnost fotosintetskih pigmentov in antocianov. Ugotovili smo, da bi lahko miskantus uporabili kot energetsko rastlino, pri čemer bi njegovo uporabo lahko še razširili na čiščenje odpadnih voda v razpršenih naseljih. V eni rastni sezoni bi lahko očistili do 3 000 000 litrov odpadne vode na hektar.Fragmented settlement structure and an intense agricultural production, most developed in areas with the largest amount of groundwater are typical characteristics of Slovenia. Recovering drain water and waste water treatment in small settlements are among Slovenia\u27s top priorities. At the same time, Slovenia must ensure at least a 20 percent energy share of energy from RES ‒ renewable energy sources (EU Directive on the promotion of the use of energy from renewable sources). The goal of our thesis was to establish whether waste water treatment in smaller settlements can be carried out with the help of miscanthus (Miscanthus x giganteus), an energy crop with efficient phytoremediation ability. For this purpose, the artificial fertilisers would be replaced with waste sources which seems a very auspicious opportunity to decrease production costs and at the same time decrease the input cost of the waste source treatment process. In 2014, we have planted miscanthus in four sampling units. Unit 1: where necessary, we additionally fertilised the plants with artificial fertilisers, Unit 2: where necessary, we watered the plants with waste water, Unit 3: where necessary, we watered the plants with rainwater, Unit 4: the plants were exposed to natural conditions, without any additional fertilisers or solutions. A year later, in the second growing season, we monitored various plant parameters twice per month (every 10 days), the photochemical efficiency of the photosystem II and the content of photosynthetic pigments and anthocyanin. We established that miscanthus could be used as an energy crop, while we could further expand its use in the area of waste water treatment in fragmented settlements. We could treat up to 3 000 000 litres of waste water per hectare