Abstract: An improved method for maintaining a granular medium filter in a clean, operable condition is disclosed. The time interval required for the level of liquid above the filter bed to drain from a backwash outlet level to the upper bed surface level following a backwash cycle is monitored. Upon this measured draindown time exceeding a predetermined interval of time, a chemical cleaning cycle is initiated for the granular medium bed filter.

Abstract: An improved method for operating a down-flow granular medium filter is disclosed which increases the effective filtration time between backwashes. The filter tank cell is divided into a plurality of subcells, each individually adapted and controlled for periodic intermittent upwardly-directed pulses of fluid passed through the filter bed within each subcell from an array of orifices beneath or in the bed. During the filtration run, one subcell is pulsed to improve the porosity of that portion of the filter bed while the remainder of the subcells continue to filter wastewater. After initiation of the first pulsing cycle for a subcell, additional subcell pulsing cycles are initiated sequentially. At the end of the filtration run the whole filter cell is backwashed to remove particulate matter from the bed and prepare the bed for the next filtration run.

Abstract: A single-stage continuous aeration-batch clarification process for purifying wastewater containing pollutants includes the steps of continuously aerating the wastewater in the presence of biologically active solids and powdered absorbent in an aeration zone. A portion of the mixture of wastewater, biologically active solids and powdered absorbent is transferred to a settling zone where a settled solids phase and a clarified liquid phase are formed. During the settling step additional wastewater flows into the aeration zone. The clarified liquid phase is discharged from the settling zone while the settled solids phase may be returned to the aeration zone or sent to disposal.The process may be carried out with a single aeration basin and settling basin or with a plurality of aeration basins using a single settling basin.

Abstract: A two-stage process for purifying wastewater includes the steps of biophysical anaerobic treatment to remove the majority of the COD, followed by biophysical aerobic treatment to further purify the wastewater. A powdered adsorbent, preferably powdered activated carbon, is used with biological solids in each treatment step. Excess biophysical solids from the aerobic step are transferred to the anaerobic step for digestion. Fresh powdered adsorbent is added to the aerobic treatment step to compensate for that transferred to the anaerobic treatment step. Solids concentration in the anaerobic step is controlled by wasting solids to disposal.

Abstract: A two-stage, batch process for purifying wastewater containing organic and adsorbable pollutants includes the steps of introducing a predetermined quantity of the wastewater into an aeration and settling zone of a primary treatment zone and aerating therein in the presence of a powered absorbent, such as activated carbon, and biologically active solids, terminating aeration and retaining the thus-treated wastewater in the aeration and settling zone a sufficient time for a substantial portion of the suspended solids to settle by gravity. A predetermined amount of the partialy-treated wastewater is withdrawn from the aeration and settling zone and introduced into a contact zone wherein it is agitated, preferably by aeration, in the presence of a powered adsorbent, agitation is terminated and the solids are allowed to settle by gravity. After completion of settling, clarified, substantially solids-free water is withdrawn from the contact zone.

Abstract: Water contaminated with at least one volatile compound is treated by air stripping the volatile compound into the gas phase, then removing the volatile compound from the gas phase by contacting it with an aqueous mixture of biological solids and powdered adsorbent. The partially-purified water is further treated by a biophysical aerobic process which in turn produces the aqueous mixture of biological solids and powdered adsorbent used to remove the volatile compound from the gas phase. The aqueous mixture of biological solids and powdered adsorbent containing the volatile compound is thickened and the solids slurry treated by regeneration, preferrably wet air oxidation, to destroy the biological solids and volatile compound as well as regenerate the powdered adsorbent. The regenrated adsorbent may be returned to the biophysical aerobic treatment process.

Abstract: A process and apparatus for protecting a media bed filter with underlying support screen from solids contained in a liquid, such as filtrate from the filter, used to regenerate or backwash the media bed filter. Filtrate enters a first collection chamber containing a screen assembly covering one outlet, the chamber also containing a second outlet. Filtrate traverses the screen assembly and is transferred to a second collection chamber with addition of a predetermined amount of bactericide to prevent solids growth therein. Upon bactericide-treated filtrate reaching a predetermined level within the second chamber, filtrate in the first chamber bypasses the screen assembly and flows out the second output to further biological treatment or use. Bactericide-treated filtrate from the second collection chamber is used to regenerate or backwash the media bed filter with addition of optional surfactant to assist in cleaning the filter media and underlying support screen.

Abstract: A method for operating a continuous wet oxidation system for destroying cyanide in caustic cyanide and metal wastes which scale upon heating. Raw waste is introduced into the wet oxidation reactor without heating while a mixture of heated dilution water and oxygen containing gas is introduced into the reactor by a separate inlet. The reactor is fitted with a pair of valved effluent lines and corresponding valved lines for introducing dilute mineral acid into each effluent line at system pressure. Oxidized effluent and offgases exit through a first effluent line while dilute mineral acid flows through a second effluent line into the reactor to prevent scale buildup. Periodically the flows are alternated such that oxidized effluent and offgases exit through the second effluent line and dilute mineral acid flows through the first effluent line into the reactor to remove scale. The oxidized effluent and offgases are then cooled and separated.

Abstract: A two-stage process for purifying wastewater containing organic and adsorbable pollutants includes the steps of first aerating the wastewater in the presence of a powdered adsorbent, such as activated carbon, and biologically active solids in the aeration zone of a primary treatment zone which also includes a quiescent zone. The thus-treated water passes from the aeration zone to the quiescent zone where it is retained a sufficient time for a substantial portion of the suspended solids to settle by gravity. The partially-treated wastewater overflowing from the quiescent zone is introduced into one or more contact zones wherein it is agitated, preferably by aeration, in the presence of a powdered adsorbent, agitation is terminated and the solids are allowed to settle by gravity and, after completion of settling, clarified, substantially solids-free water is withdrawn from each contact zone.