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Growth and fatty acid production of microalga Selenastrum sp. with associated bacteria was studied in lab-scale experiments in three composting leachate liquids. Nutrient reduction in cultures was measured at different initial substrate strengths. A small, pilot-scale photobioreactor (PBR) was used to verify lab-scale results. Similar growth conditions supported growth of both Selenastrum and bacteria. CO feed enhanced the production of biomass and lipids in PBR (2.4gL and 17% DW) compared to lab-scale (0.1-1.6gL and 4.0-6.5% DW) experiments. Also prolonged cultivation time increased lipid content in PBR. At both scales, NH-N with an initial concentration of ca. 40mgL was completely removed from the biowaste leachate. In lab-scale, maximal COD reduction was over 2000mgL, indicating mixotrophic growth of Selenastrum. Co-cultures are efficient in composting leachate liquid treatment, and conversion of waste to biomass is a promising approach to improve the bioeconomy of composting plants.

Malodors from pig manure storage pits are a problem lacking a cost-efficient solution particularly for small pig (Sus domestica) farms. The objective of this study was to reduce emissions of noxious odorants by changing the conditions in the pig manure to favor an altered microbial community. Sugars (maltose, lactose, and saccharose), carbohydrate-rich waste (maltose syrup and wheat flour), and bacterial amendments (Lactobacillus plantarum and L. amylophilus) were tested for their effect on manure pH, bacterial community, and gaseous emissions. In laboratory experiments, a permanent pH reduction was achieved with all carbohydrates when added to a 5% final concentration. Maltose significantly decreased emissions of sulfur-containing compounds, whereas bacterial amendments had little effect on odorants. Lactobacilli were found in manure receiving carbohydrate amendments alone, but Clostridiales, Bacteroidetes, and Enterobacteriaceae were observed in all treatments (including the control). At the mesocosm (60 L) level, maltose syrup and wheat flour amendments caused clear pH reductions in manure, whereas L. plantarum and L. amylophilus had no additional effect. The addition of maltose syrup and wheat flour to a manure storage pit (600 m(3)) lowered the pH slightly. When the manure was spread onto the fields, the observed reduction in odor was found to be reversible, and the release of malodors was delayed rather than eliminated. We conclude that these methods require further development to produce a reliable technical application.