Sewage Streams Research Articles

Fermentation of Raw Sludge and Elutriation of Resultant Fatty Acids to Promote Excess Biological Phosphorus Removal

Research in South Africa has highlighted the dependence of biological phosphate removal mechanisms on the presence of certain minimum concentrations of some readily biodegradable materials including interalia volatile fatty acids. Generation of these compounds was achieved on an experimental basis at the Johannesburg Northern Works by the fermentation of primary sludge either in primary settling tanks or off-line in high rate “acid” digesters. Elutriation of the volatile fatty acids from the sludge was achieved by recycling the sludge to the influent sewage stream. Significant improvements in phosphate removal were observed and it was decided to design primary sludge treatment facilities to specifically generate the volatile fatty acids. This paper describes the design philosophy adopted and discusses the preliminary results obtained from the recently commissioned plant at the Johannesburg Northern Works and Bushkoppie plants.

Japan's Aqua Renaissance '90 Project

Aqua Renaissance' 90 is a six year R & D project for water reuse and energy recovery supported by the Japanese Ministry of International Trade and Industry. The objective is to develop low cost treatment processes utilizing bioreactors coupled with membrane separation units to produce reusable water from industrial waste water and sewage. Polymeric and ceramic membranes in capillary, hollow fiber, tubular and plate and frame modules have been tested in conjunction with bioreactors on a number of actual waste water and sewage streams. This paper will focus on membrane performance and power consumption. Recent results from test plant operation indicate that treatment of concentrated waste water by membrane separation units uses less than a third of the conventional power requirement.

Evaluation of gauze pad method to recover viruses from water

Field studies using the gauze pad method were compared with the grab sample method. It was found that the gauze pad proved to be more effective, for detecting enterovirus, than two-liter volume grab samples, taken from the same sewage stream and concentrated by the phase separation method. No advantage was found in keeping the pad immersed longer than 24 h in the water stream being tested. On the other hand, laboratory experiments for evaluation of gauze pads show that the recovery efficiency for concentration of viruses with gauze pads from water is very low and dependent on sample volume—the larger the volume the lower the efficiency.

Oxygen Absorption in Streams

Information on the rate of absorption of oxygen in sewers is needed for calculations of biological oxidation in sewers and for an understanding of sulfide buildup in sewers. Published equations for stream aeration are at variance with one another, and in any case do not provide a basis for needed predictions of reaeration rates in sewers. Measurements of oxygen uptake were made in twelve functioning sewers. By viewing all of the data and prior mathematical treatments synoptically, a general predictive equation was devised. Reaeration rates for sewage streams can now be predicted with an expected standard error of ±10%. The general equation coefficient for predicting reaeration in streams of pure water is not yet known with similar accuracy, but could be determined by precision experiments. The rates in sewage streams are apparently about a third as great as in pure water.

DISCUSSION. THE USE OF RADIOACTIVE ISOTOPES FOR THE INVESTIGATION OF SEWAGE TREATMENT PLANT.

Keywords LONDON COUNTY COUNCIL USE, RADIOACTIVE, ISOTOPES, INVESTIGATIONS, SEWAGE, TREATMENT, PLANT, WORKS, HYDRAULIC, SYSTEMS, MODELS, SEDIMENTATION, TANKS, BEHAVIOUR, EXPERIMENTS, TESTS, SLUDGE, IMMERSION, TECHNIQUES LONDON, MOGDEN UK... Show All