Utilization of Waste from Methane Fermentation in Lemnaceae Plant Breeding Intended for Energy Purposes

The increase in environmental pollution caused by waste from agro-food industry and methane fermentation in biogas plants is currently one of the most serious problems. More and more governments launch programs supporting biogas plant construction and conversing biogas into electric energy. One of the methods to utilize the waste from methane fermentation in biogas plants is its utilization as a culture medium for breeding Lemnaceae aquatic plants. Water biomass can be diversely used in agriculture, energy production, phytoremediation and as animal feed. The plants Spirodela polyrrhiza were cultured in a phytotronic room at 24 °C. The medium was supplemented with various concentrations of leachate coming from the process of methane fermentation from biogas plants. The following physiological parameters were measured (i) plant gas exchange i.e. net photosynthesis (mmol H₂O/m⁻² s⁻¹), transpiration (mmol H₂O/m⁻² s⁻¹), stomatal conductance (mmol H₂O m⁻² s⁻¹), and intercellular CO₂ concentration (μmol CO₂ mol air⁻¹), (ii) index of chlorophyll content and (iii) fresh and dry matter. The obtained results justified the use of post-fermentation leachate to supplement the culture medium thus indicating the possible way of its utilization. This method can be an efficient way to recycle waste from methane fermentation in biogas plants, to develop a cost-effective system of high-quality water biomass production with an array of applications in production of liquid and gaseous biofuels, in agriculture (animal feed, fertilizers) and phytoremediation. This will decrease the costs and limit environmental pollution.