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SummaryA laboratory-scale research program was undertaken to investigate the kinetics of the mesophilic (37°C) anaerobic digestion of brewery industry by-product. The purpose waa to develop data for the design and operation of full-scale units which could be used to generate methane fuel gas from these materials. This is important because the brewery industry has been susceptible to shortages of natural gas in recent years. The minimum SRT is 2.3 days, although for design purposes as much as ten days is recommended. The biomass yield is 0.512 g volatile suspended solids (VSS)/g volatile solids (VS) or 0.421 g VSS/g chemical oxygen demand (COD). The maintenance requirement is 0.052 g VS/g VSS per day or 0.061 g COD/g VSS per day. The specific methane yield is 2.51 liter/g VSS, and the methane productivity is 0.32-0.41 liter/g dry Substrate added or 0.69-0.91 liter/g destroyed. The maximum loading rate for which substrate inhibition is not observed is 6 g dry substrate added per liter per day. The results of the entire program indicate that processing brewery by-product in this manner is both technically feasible and economically attractive.

Important advances have been made recently in identifying the sources of algal‐available P in soils and sediments. Algal bioassays have shown that considerable amounts of the total soil P may be algal‐available under the appropriate environmental conditions. At present, however, the reported research contains no convincing evidence that the bioassay techniques used quantitatively measured all of the algal‐available P present in the soils and sediments tested,. Although chemical fractionation procedures have shown from which fractions algae obtain P, there is no evidence that all of the chemically extracted P in those fractions is algal‐available. Quantitative assessment of algal‐available P in soils and sediments will depend upou the development of long‐term algal assay procedures.