Abstract: The process and apparatus of the present invention provides an anoxic pretreatment tank, a granular fixed film denitrification reactor and a membrane bioreactor. Raw waste flows into the anoxic pretreatment tank, through a denitrification filter and then to a membrane bioreactor for nitrification and micro filtering. Contents of the membrane bioreactor are periodically recycled to the anoxic tank and the denitrification filter for BOD reduction, denitrification and coarse filtration.

Abstract: The present invention relates to a treatment system for treating primary waste onsite. The treatment system includes a separation cone which separates the solid waste from the liquid waste and the different wastes are subsequently treated separately. The solid wastes are subject to aerobic decomposition by worms and other suitable organisms while liquid wastes are filtered through alternate layers of coarse and fine filter media. The resulting treated liquid can be recirculated or pumped out of the system for other purposes or further treatment. The treatment system is designed as a compact modular system and maybe used for the treatment of domestic human waste.

Abstract: A leach field of a sewage system is dewatered, to restore its function when it is at or near failure. In various embodiments, water is withdrawn from the points in the leach field, preferably from the conduits, by means of suction or sub-atmospheric pressure. As water is drawn from the soil, air from the atmosphere or from an air mover enters resultant spaces in the soil, to restore the influence zone and better treat waste water. Forced air flow is used to fissure the soil, to aid dewatering, and separately, to restore the leach field.

Abstract: Highly porous, beads are comprised of a polymer and a second compound mixed into it. The second compound, an amendment, is either a nutrient or a compound having high affinity to one or more nutrients. A plurality of these beads may be exposed to an aqueous environment, usually a body of water. Bacteria and other microorganisms rapidly enter and remain within the nutrient filled interior space of the beads. Any of a number of various detection methods may then be used to characterize, detect and/or identify the microorganisms.

Abstract: The method of providing for a fluid treatment, that includes providing a treatment zone containing granular activated charcoal, and providing a stream of water containing nutrients, contaminant degrading microbes and dissolved oxygen, and introducing the stream to a treatment zone to effect adsorption of nutrients and microbes onto the granular activated charcoal, thereby to provide a contaminant treatment matrix, whereby contaminant in fluid flow through the matrix is reduced.

Abstract: A filtration bed support for biolytic filtration wherein the filtration bed comprises a bed of solids in various stages of decomposition ranging from raw unprocessed organic material on the surface of the bed to fully decomposed humus which forms the bulk of the bed. The bed is kept from blocking by living organisms. The support comprises a three dimensional humus matrix lattice.

Abstract: A heated ultrasonic treating device (6) comprising a sump (13) through which suspended matter-containing liquid passes, a temperature-controllable heater (14) disposes in the sump (13), and a ultrasonic vibrator (15) disposed in the sump (13). The heated ultrasonic treating device (6) uses the ultrasonic vibrator (15) to apply ultrasonic waves while heating organic drain passing the sump (13) with the heater (14), thereby pulverizing suspended matters and reducing the amount of SS. In addition, a treating column, where pulverized suspended matter-containing liquid is aerobically treated by aerobic microorganisms, is prevented from efficiency lowering due to clogging.

Abstract: A wastewater treatment system includes a tidal, sequential vertical flow marsh cell system having at least three marsh cells in serial forward fluid communication. Incoming wastewater to be treated is channeled to at least the first and a second marsh cell, and a portion of water exiting a final marsh cell, to the first marsh cell surface. Each marsh cell is alternately flooded and drained for enhancing aeration of incoming water and marsh cell contents, which include media and plant roots having biofilms growing thereon, the biofilms including a population of nitrifying and denitrifying bacteria, for achieving substantially simultaneous nitrification and denitrification of the wastewater.

Abstract: The present invention refers to an apparatus for the biological treatment of waters, either fresh or salt waters, in aquarium and in basins for aquaculture, comprised of at least one reactor tank, where the water is treated by the action of aerobic and anaerobic microorganisms.

Abstract: The present invention provides a method for treatment of wastewater containing organic sulfur compounds The method includes introducing the wastewater into an apparatus body equipped with a fixed bed in which fixed carriers for the attachment of microorganisms are filled and a fluidized bed in which flowing carriers for the attachment of microorganisms are flown, and enabling the wastewater to flow through the fluidized bed towards the fixed bed so that the wastewater is biologically treated by the fluidized bed and the fixed bed.

Abstract: A polluted water treatment system 10 operated to reduce impurities in sewerage polluted water to an acceptable level for dumping. The system includes a horizontal subsurface filter (HSF) 12 having an inlet zone 18 through which the inflow of polluted water is permitted to pass, a treatment zone 20 which permits the polluted water to undergo treatment by removal of at least some of the impurities of the polluted water and an outlet zone 22 from which the treated polluted water flows from the HSF 12. The impurities may include, for example, organic materials (BOD and COD) and oxidization processes within the HSF may reduce the quantity of the nitrites that are dumped from the outflow zone 22. The outlet zone 22 also includes a collection well 28 having a pump 30 located therein to recycle the treated effluent back to either the inlet zone 18 of the HSF 12 or to a secondary vertical filter 40.

Abstract: A method of wastewater/water treatment includes introducing an influent into a reactor so that a portion of contaminants in the influent is decomposed by microorganism in the reactor during a retention time of the influent in the reactor, and thus an effluent has a less amount of contaminants in comparison with the influent. The microorganism is grown fixedly on modified porous carriers in the reactor. The modified porous carrier contains a polymer foam and adsorbent particles entrapped in pores of the polymer foam, so that the modified foam not only has a large specific surface area, but also characteristics such as water affinity or an affinity to a certain type of contaminants. As a result, the efficiency of reducing contamination in the influent water is enhanced.

Abstract: A treatment and irrigation system for relatively large tracts of land used for sports, public gardens, recreation, agricultural crops, or other land uses, wherein the output from a primary or secondary sewage treatment plant is received by a drip, or trickle, irrigation system which is disposed over a relatively large area to be irrigated, immediately under a stratum for receiving the roots of flora to be irrigated and above a layer of very permeable matter which receives the output of the sewage treatment plant. Such output, which is received, in part, through capillary action by flora growing on the upper stratum, drips through the permeable matter layer wherein the output is subjected to an aerobic action due to air in that layer. The permeable layer rests on underlying non-permable base although this also may also be permeable ground.

Abstract: The invention recites a filter comprising a block including an outer wall defining an inner chamber and a block exterior, and a conduit having a conduit wall, a first conduit end, a second conduit end, and an inner flow path providing fluid communication between the first and second conduit ends. The conduit wall includes an orifice therethrough. The conduit is coupled to the block such that the first conduit end is in fluid communication with the inner chamber of the block and the second conduit end and the orifice are in fluid communication with the block exterior.

Abstract: A dispersal field for a wastewater treatment system of the type used in conjunction with a septic tank, the dispersal field including multiple conduits, each conduit having at least one discharge opening. The configuration of each conduit and the size and position of the discharge openings causes wastewater flowing into the conduits to stand in each of the conduits below the level of the discharge openings until it has a BOD of less than about 125 mg/l.

Abstract: A process for treating a body of water in which a bioreactor and a water eductor are located in a body of water such that the eductor is submerged beneath the body of water to a depth of at least about 3 feet. The water eductor produces a water flow at a rate of at least about 60 feet per minute; the water flow is substantially parallel to the surface of the body of water. Water is also passed through a bioreactor that contains a plurality of bio-suspension elements within an enclosure located above a screen in the enclosure.

Abstract: The invention relates to a process and installation for treating a polluted aqueous liquid having a COD value caused by organic compounds present therein and a BOD/COD ratio smaller than 0.2. To reduce the COD value, the polluted aqueous liquid is percolated through a packed filter bed (7) of a carrier material, in particular of activated carbon, which is colonised with aerobic bacteria and which forms an adsorbent for at least part of said organic compounds. To provide a thin, fully aerated biofilm of bacteria on the carrier material so that no oxygen has to be dissolved under pressure in the liquid, the filter bed is kept at the most partially submerged in the liquid percolating therethrough.

Abstract: To purify wastewater discharged from lavatories (3), a wastewater purifying apparatus having a shell contact aeration chamber (6, 7) placed with shell microbial carrier members (15), the wastewater being fed to and purified in the shell contact aeration chamber (6, 7). Shells whose mother-of-pearl layer on the inner surface (b) is at least removed are used as the microbial carrier member (15).

Abstract: A new biofilm-activated sludge Sequencing Batch Reactor (SBR) treatment process for sewage or wastewater has successfully been developed as the third generation SBR (SBR3). This new SBR3 process utilizes a multi-stage and multi-sludge SBR configuration receiving either continuous or intermittent inflow of wastewater. Each stage has individually controlled continuous or alternating anaerobic/anoxic/aerobic operation, with or without mixing and recycling from the other stage(s). The configuration and operation is dependent upon the treatment objectives and effluent discharge requirements. In the preferred embodiment, carriers are used to facilitate control of operating conditions.

Abstract: A system, apparatus and method for treating water in a landscape pond so as to enhance the water clarity, where the water to be treated is delivered to a treatment pond to reduce the particulate matter and nutrient level of the water. The treatment pond includes a nutrient level reducing vegetation, facultative bacteria, substrate material for the bacteria (usually gravel) and a treatment apparatus. The treatment apparatus includes a generally vertically disposed hollow and cylindrical stack formation which extends between the treatment pond bottom and surface and defines at least one (1) coupling construction. At least one (1) elongated and generally horizontally disposed water disbursing module is positioned on the pond bottom and coupled to the stack formation. The disbursing module includes a flat bottom, an arcuate upper surface having a plurality of exit apertures therein and a pair of end formations, all of which define a passageway.

Abstract: The present invention provides a supported catalyst for in situ remediation of soil and/or groundwater contaminated with a halogenated hydrocarbon comprising an adsorbent impregnated with zero valent iron, wherein the adsorbent is capable of adsorbing the halogenated hydrocarbon. This invention further provides a bioremediation composition for in situ bioremediation of soil and/or groundwater contaminated with hydrocarbons, comprising an adsorbent capable of adsorbing said hydrocarbons, a mixture of facultative anaerobes capable of metabolizing said hydrocarbons under sulfate-reduction conditions, a sulfate-containing compound that releases sulfate over a period of time, and a nutrient system for promoting growth of said anaerobes, wherein said nutrient system includes a sulfide scavenging agent.

Abstract: The present invention provides a method of treating groundwater or other water stream(s) contaminated with an oxygenate to degrade said oxygenate which comprises: a) inoculating a biodegrader capable of degrading said oxygenate on a packed activated carbon bed through a rigid tubular instrument having a plurality of holes in the part of the rigid tubular instrument used for inoculation of the carbon bed; and b) flowing said groundwater, or other water stream contaminated with said oxygenate through a structure having a top, bottom and sides and a predetermined volume containing said bed of activated carbon having said biodegrader inoculated thereon. and an apparatus for the same. The method is particularly effective for treating water contaminated with methyl t-butyl ether (MTBE) and/or t-butyl alcohol (TBA).

Abstract: In one embodiment, a filter media tower assembly is provided comprising a first portion and a second portion, wherein the first portion is suspended within the second portion. The first portion is a removable media tower or cage for holding filter media, whereas the second portion is a media tower guide support structure that is mounted to a surface of a tank.

Abstract: A method of wastewater/water treatment includes introducing an influent into a reactor so that a portion of contaminants in the influent is decomposed by microorganism in the reactor during a retention time of the influent in the reactor, and thus an effluent has a less amount of contaminants in comparison with the influent. The microorganism is grown fixedly on modified porous carriers in the reactor. The modified porous carrier contains a polymer foam and adsorbent particles entrapped in pores of the polymer foam, so that the modified foam not only has a large specific surface area, but also characteristics such as water affinity or an affinity to a certain type of contaminants. As a result, the efficiency of reducing contamination in the influent water is enhanced.

Abstract: A system and method for removing contaminants from water that has a relatively low oxygen content with naturally occurring chemoautotrophic bacteria, ferrous iron, manganese, sulfide, and other contaminants. The system comprises an oxygenation vessel for oxygenating the water and a filtration vessel having bio-filtration media with surfaces that are exposed to the oxygenated water. The chemoautotrophic bacteria propagate in the presence of the oxygenated water and deposit certain of the contaminants on the bio-filtration media as by-products. The contaminants are also precipitated in the presence of the oxygenated water and settle on the bio-filtration media in at least the filtration vessel. A secondary filtration stage can further remove contaminants from the water that were not sufficiently removed by the first filtration stage.

Abstract: A biofilter material for biofiltering a fluid is disclosed. This biofilter material comprises fragments of coconut mesocarp. A wastewater treatment system is also disclosed and comprises a filter bed and a water distribution system. The filter bed comprises fragments of coconut mesocarp as a biofilter material.

Abstract: A closed bioreactor for high organic carbon removal and ammonia conversion in high-strength wastes under microgravity conditions. Oxygen is provided to the bioreactor by diffusion through a non-porous hydrophobic membrane in a recirculation line, allowing a high rate of oxygen transfer while minimizing the opportunity for formation of bubbles. Operating the bioreactor as a closed unit at elevated pressures keeps the oxygen in the dissolved phase. The oxygen transfer within the reactor is thus much more efficient and uniform than in similar reactors having both a liquid and gaseous phase.

Abstract: The present invention relates in general to a method for bacterially treating small-tank toilet systems and an apparatus for using same, and in particular, bacterially treating small-tank portable toilets, such as toilet systems in airplanes, busses, campers, trains, boats, and free-standing portable toilets.

Abstract: Disclosed are methods, devices and apparatus for bioremediation of mixed waste aquifers, based on a synergistic combination of reductive treatment using zero-valent iron and anaerobic biotransformations. Also disclosed are methods for in situ and ex situ remediation of groundwater and wastewater via these iron-bacterial compositions in a variety of devices including batch reactors, permeable and semipermeable reactive barriers, flow-through reactors, fluidized bed reactors, and sediment tanks.

Abstract: A novel method and apparatus for treating wastewater is described which involves the use of a downflow bioreactor filled with active anaerobic granular biomass. Influent wastewater is evenly distributed across the biomass and passes downward through the granules. The system is simple to use since it does not require the use of mixers, gas/solids/liquid separators, heat exchangers, or other sophisticated equipment. Treated water from the system has a solids content of 30 mg/L or less.

Abstract: The present invention provides a water treatment apparatus and method for reducing toxicity in zinc containing acid stormwater runoff, the apparatus comprising a first filtrate layer of high calcium material a last filtrate layer comprising a drainpipe arrangement embedded within an aggregate; and at least one intermediate filtrate layer comprising a wood mulch material positioned between the first filtrate layer and said last filtrate layer.

Abstract: The present invention provides a floated biological treatment apparatus and a process for purifying refractory wastewater or raw water for drinking water. The treatment apparatus of the present invention includes a supporting plate for dividing the treatment apparatus into upper and lower portions. The upper portion is formed into a reactor, and porous compressible carriers are filled with the reactor in an amount of 80 vol % to 100 vol % of the reactor volume. The lower portion is provided with a liquid inlet for introducing the refractory wastewater or raw water and a gas inlet. The reactor is provided with at least one top carrier blocking plate at the top, such that the carriers can be limited by the top carrier blocking plate to be retained in the reactor, and the carriers can become a floating state.

Abstract: A method for denitrification of water, in which the water to be denitrified is made to flow over a porous carrier which comprises a transition metal, preferably palladium, used in an amount between 0.01 and 5% by weight on the carrier and on which denitrifying bacterial strains capable of surviving in the presence of hydrogen are made to adhere, and in which hydrogen is used as a reducing agent and the pH of the reaction is adjusted to values of 4.5 to 7.8 preferably by using carbon dioxide.

Abstract: The wastewater treatment method of the present invention includes introducing an influent water to an oxygen-supply tank for aeration; introducing the oxygen-enriched water from the oxygen-supply tank into the bottom of an activated carbon tank, so that the oxygen-enriched water flows upward and expands the activated carbon bed. When the oxygen-enriched water flows through the activated carbon bed, the microorganisms on the activated carbon particles use the enhanced oxygen concentration to decompose the contaminants, such as COD, BOD, TKN, etc., that are contained in the water or adsorbed on the activated carbon particles. Most of the supernatant liquid in the activated carbon tank is recycled to the oxygen-supply tank for aeration, and a small amount of the liquid is discharged, thereby performing a suitable treatment on wastewater having various qualities by controlling the amount of oxygen supply in the oxygen-supply tank and the recycle ratio of (the oxygen-enriched water)/(the influent water).

Abstract: The invention concerns a method and installation for the treatment of excess sludge derived from biological wastewater treatment plants. The method is characterized in that it consists of associating at least one digestion step (4) and at least one wet oxidation step (2) of said sludge, said wet oxidation step being conducted at a temperature of between 50° C. and 180° C. and at a pressure of between 2 and 40 bar.

Abstract: A system is provided for withdrawing permeate from a substrate. The exemplary system includes a vessel configured to contain substrate, two or more compartments configured to receive substrate from the vessel and to return a portion of received substrate to the vessel, and a filter positioned at least partially within each of the compartments and configured to separate permeate from substrate during operation of the filter. At least one of the compartments is configured to contain cleaning solution and substantially prevent cleaning solution from contacting substrate in the vessel during cleaning of the filter. The exemplary system is configured for cleaning the filter in situ in at least one of the compartments while operating the filter in at least one other of the compartments. A method for adapting a filtration system for cleaning thereof and a method for withdrawing permeate from a substrate using a filtration system are also provided.

Abstract: Phosphate-contaminated water passes through a domestic sewage treatment system, in which oxidation of the ammonium progresses far enough to cause a lowering of the pH to 5 or less. The water is passed over sand grains coated with aluminum hydroxide (gibbsite). Enough Al3+ ions enter solution, at the low pH, to cause all the phosphate-P to precipitate as aluminum phosphate, and nothing else precipitates other than the aluminum phosphate.

Abstract: Improved biofilters for treating wastewater are disclosed. Specifically, certain aspects of the inventive biofilter comprise a water-tight, leak proof container housing a plurality of sacks stacked upon one another. Alternatively, the water-tight container may contain course sand for use as a re-circulating sand filtration unit. In the first embodiment, each sack contains a composition of filtering material through which the wastewater influent flows prior to removal from the biofilter via a pump tank. Other aspects of the present invention include a biofilter having a plurality of apertures disposed through the floor and through which the wastewater effluent may flow to the underlying ground. The invention is also directed to novel compositions of filtering material for use in the inventive biofilters as well as conventional biofilters. Preferred compositions comprise peat, coconut fibers, large or open cell film block pieces, and course sand.

Abstract: The present invention is related to a method for treating high-concentrated organic wastewater, such as night soil or livestock wastewater, which has high levels of nitrogen and phosphorous. In particular, it is related to a method for treating night soil or livestock wastewater having high levels of nitrogen and phosphorous, comprising an anaerobic ammonium oxidizing (Anammox) step and a biopond step. The process for treating wastewater according to the present invention provides good efficiency in removing organic material and nutrients.

Abstract: A single tank submerged membrane bioreactor for treating feed water having unacceptable levels of ammonia or total nitrogen has both a membrane scouring bubble supply and an oxygenating bubble supply. The membrane scouring bubble supply continuously provides large scouring bubbles to clean the membranes. Permeate is continuously withdrawn from the membranes at a high rate but the large scouring bubbles do not transfer sufficient oxygen to the mixed liquor to create aerobic conditions in the reactor. The oxygenating bubble supply is operated to provide small bubbles of air or oxygen that intermittently produce aerobic conditions in a significant part of the mixed liquor. Alternating aerobic and anoxic conditions occur in a significant portion of the tank suitable for nitrification and denitrification.

Abstract: A method and apparatus is provided for the continuous microbial remediation of organic wastes in sewers and other waste-laden environments utilizing in-situ microbial seeding. A bio-reactor containing inoculated carrier media is suspended within a sewer wet-well or other similar environment, and is at least partially immersed in the waste-laden fluid to be treated. Air and nutrients are continuously supplied to the bio-reactor via conduit from a remote, easily accessible location. Beneficial microbial populations are permitted to thrive and spread throughout the waste-laden environment, mineralizing organic wastes and eventually becoming dominant within the subject environment.

Abstract: There is disclosed a process for nitrifying denitrifying organic waste water to nitrify and denitrify the nitrogenous components in the waste water, which comprises making use of a microbe carrier composed of an organic thermoplastic high molecular compound (thermoplastic polyurethane) in both a nitrifying step and a denitrifying step, preferably in an alternate and repeated manner, wherein the compound has, in a state of complete swelling in water, a water absorption rate in the range of 50 to 3500%, a compressive yield stress of at least 1.0 MPa each being defined by a specific formula, and a particle diameter in the range of 1.0 to 30 mm. The process is capable of efficiently performing nitrifying and denitrifying steps, steadily achieving high treatment performances, contriving compactification of the treatment facility, and curtailing the treatment time and treatment cost, while the microbe carrier can withstand long-term service without any trouble.

Abstract: A wastewater treatment system for use with a conventional septic tank, or other small-scale wastewater treatment facility, for enhancing wastewater treatment without requiring complex control or maintenance limitations. The system incorporates a plurality of primary functions that combine to oxidize, nitrify, denitrify and remove water borne total dissolved solids prior to effluent discharge. Included is a fluidized-bed reactor containing biofilm attached to carrier particulates for use in the purification of wastewater. The fluidized-bed reactor is configured to include two distinct regions, namely a “lower” aerobic region and an “upper” anoxic region, during normal operating conditions. The lower aerobic region uses aerobic facultative bacteria to oxidize Carbonaceous Biochemical Oxygen Demand (CBOD), organic (Kjeldahl) nitrogen, and ammonia while consuming the dissolved oxygen in the water.

Abstract: The method of providing for a fluid treatment, that includes providing a treatment zone containing granular activated charcoal, and providing a stream of water containing nutrients, contaminant degrading microbes and dissolved oxygen, and introducing the stream to a treatment zone to effect adsorption of nutrients and microbes onto the granular activated charcoal, thereby to provide a contaminant treatment matrix, whereby contaminant in fluid flow through the matrix is reduced.

Abstract: The present invention relates to a compact, environmentally benign onsite waste water treatment and disposal system installed secondary to conventional primary treatment process. It is a method and apparatus for the biological purification and natural disposal of liquid wastes using a secondary single pass trickling filter in conjunction with an evapotranspiration absorption (ETA) tertiary disposal bed.

Abstract: A high-rate reactor system, (applying a high superficial velocity), capable of treating partially soluble, complex, high-strength wastewater. The reactor system is configured in multiple stages and has the ability to retain complex insoluble substrates in a wide range of particle sizes in spatially separate stages for sufficient residence time to enable complete degradation. A vertically oriented vessel has neighboring upper and lower chambers, each chamber having a gas retention space and a liquid retention space. A filter chamber has an inlet communicating with the liquid retention space of the lower chamber and an outlet communicating with the liquid retention space of the upper chamber. A gas conduit communicates the gas retention space of the lower chamber with the gas retention space of the upper chamber. A discharge device enables gas to be periodically discharged from the lower chamber to the upper chamber through the gas conduit.

Abstract: The present invention concerns the field of nitrification of fluids, and particularly relates to the treatment of aqueous fluids to oxidize ammonia and nitrites to produce nitrates. One aspect of the present invention seeks to provide an alternative nitrification process which is readily capable of commercial implementation, and in which the nitrification rate more nearly approaches the rate of ammonia generation. According to one aspect of the present invention there is provided a microbiological process for the nitrification of a fluid comprising passing the fluid to be nitrified through an immobilized biomass comprising nitrifying bacteria, characterised in that the bacteria are immobilized as a biofilm grown on porous particles, in particular coke.

Abstract: A metal stearate denitrification system utilizes insoluble and hydrophobic metal stearates as a carbon source for the bacterial substrate. The system in a long-term, low-maintenance denitrification cell is a flow-through plastic container having a replaceable porous liner filled with a porous and permeable mixture of metal stearate and volcanic scoria and a small amount of soil as a bacteria source. Oxidized effluent from an aerated home septic tank enters the container near its base and exits near its top. The insoluble and hydrophobic metal stearate remains in place as the fluid flows through the container. Over a time span of years, the metal stearate is gradually destroyed by bacteria using stearate as a metabolic food source. The aerobic bacteria first remove the dissolved oxygen in the entering fluid and then the anaerobic bacteria denitrify the nitrate.

Abstract: A method for purifying water including nitrification by aerobic bacteria and denitrification by anaerobic bacteria in an apparatus by providing an elongated, closed water channel.

Abstract: A method and apparatus for anaerobic treatment of organic wastes in a liquid filled vessel wherein particles of the waste are buoyed and form a floating bed in the liquid by the gasses generated by the anaerobic digestion of the wastes. The bed forms to an upper stratum of the least digested, least dense waste and a lower stratum of the most digested, most dense waste. Liquid from beneath the bed is continuously sprayed over the upper surface of the bed through a series of discharge ports which expands to bed downwardly. Each spraying period is followed by a quiescent period to allow the bed to reform. Over time the floating bed is moved from an inlet end to an outlet end of the vessel where the most digested waste is removed.