Abstract: A method for the secondary treatment of sewage (and apparatus therefor) having a step in which sewage is circulated in a system having a riser and a downcomer communicating with each other at their upper and lower ends and in which an oxygen-containing gas is supplied to the sewage as it passes through the downcomer. The method is intended for use in the aeration and/or digestion steps of the secondary treatment of sewage. The riser and downcomer are preferably located in a shaft extending into the ground for at least 40 meters below a basin containing the sewage.

Abstract: A method for the secondary treatment of sewage (and apparatus therefor) having a step in which sewage is circulated around a system having a riser and a downcomer communicating with each other at their upper and lower ends and in which an oxygen-containing gas is supplied to the sewage as it passes through the downcomer. The method is intended for use in the aeration and/or digestion steps in the secondary treatment of sewage. The riser and downcomer are preferably located in a shaft extending into the ground for at least 40 meters below a basin containing the sewage.

Abstract: Growth of bacteria belonging to new species of genera Pseudomonas, Microcyclus and Hyphomicrobium upon culture media comprising sources of assimilable carbon, for example oxygenated hydrocarbons, and inorganic nutrients to produce protein compositions and/or other fermentation products, for example amino acids. The protein compositions produced are suitable for use as protein supplements in human and animal foods.

Abstract: A process of general applicability in the microbiological field wherein a culture is subjected to periods of availability and non-availability of an essential energy source such as a carbon source, i.e. the energy source is supplied in pulses. The efficiency of the culture in converting substrate carbon to cellular carbon varies depending upon the relative duration of the periods of availability and non-availability of the energy source. Thus depending upon the relative duration chosen the process can be applied differently, i.e. when the efficiency is high the process is suitable for single cell protein production while when it is low it is suitable for waste water treatment.