Showing papers on "Trickling filter published in 1981"

Microelectrode studies of oxygen transfer in trickling filter slimes

Abstract: Slime-covered rocks and samples of process waters from two trickling filters for treatment of municipal wastes were brought to the laboratory for probing with microelectrodes to determine dissolved oxygen (DO). Slime thickness was 0.4–1.5 mm. Flow rate of medium over the slime had a minor effect on slime respiration, but pH 5 or below was strongly inhibitory. Increasing temperature showed lower oxygen concentration throughout a slime, although 27°C had results little different from those at 22°C. Medium concentration had a profound effect on oxygen concentration profiles, and either oxygen-limited or substrate limited respiration could be demonstrated. Illumination of slimes from the top of the trickling filter developed oxygen supersaturation because oxygen from photosynthesis could not diffuse away rapidly.

Process for the biological purification of waste water

Abstract: The present invention relates to a process for the anaerobic or aerobic biological purification of waste water (effluent) in a trickling filter, the waste water to be purified being conducted from top to bottom in a trickling manner via percolation bodies of a spherical shape and a density of less than 1 g/cm and to a clarifying vessel for the biological purification of waste water by percolation bodies.

Plant for purifying waste water

Abstract: The invention relates to a plant for purifying waste water (effluent). In its basic structure, the plant is composed of a mechanical clarification device for the mechanical purification of the waste water, an activation tank for a first activation stage, an intermediate clarification device, a nitrification stage equipped with a trickling filter apparatus, a denitrification stage, a secondary clarification tank and a device for conducting away and, if required, treating surplus sludge. The waste water to be purified passes from the mechanical clarification device into the activation tank and from the activation tank via the intermediate clarification device into the trickling filter apparatus and finally into the secondary clarification tank. The biocoenoses between activation tank and aeration tank are separate. The activation tank is designed as a very high loading activation tank. The trickling filter apparatus operates solely as a nitrification stage. Between the trickling filter apparatus and secondary clarification tank is arranged an unaerated mixing tank as a denitrification stage. Apart from water from the trickling filter stage, surplus sludge from the activation tank can be introduced into the mixing tank, by-passing the trickling filter stage. In order to operate the plant in such a way that it works with high purification efficiency in the purification of communal waste water, the activation tank of the first activation stage is installed for operation at an oxygen content of 0.5 to 1 mg/l and thus for partial oxidative degradation. Sludge supply in the intermediate clarification device can maintain the sludge in the first activation stage in the endogenous growth phase in which substrate respiration is established.

Energy conservation for existing wastewater treatment plants

Abstract: There is a need for energy conservation wastewater treatment and opportunities for conserving energy in existing facilities are examined. Target areas include pumping adjustments; pump maintenance and operation; plant lighting, heating, and ventilation; sludge pumping; trickling filters; rotating biological contactors; and activated sludge. Effects on overall energy utilization of solids retention time, of intermittent operation of the sludge dewatering process, and of anaerobic digestion are examined. Use of recovered anaerobic digester gas and solar energy are noted.

Evaluation of Wastewater Filtration

Abstract: Tertiary filtration of secondary wastewater is frequently used to improve wastewater treatment plant effluent quality. Four experimental filter columns were operated at the Preston, Idaho, Wastewater Treatment Plant to evaluate the effectiveness of granular media, gravity filtration. The Preston plant is a trickling filter secondary treatment plant and services a population of approximately 3600 people. Four filter medium configurations were studied. Multi-media, dual-media, and single-media beds were constructed with the following media configurations: (1) coal-sand-garnet; (2) coal-sand; (3) sand-garnet; and (4) all sand. The filters were operated at two hydraulic loading rates. Effluents from the primary clarifier, trickling filter, and secondary clarifier were filtered to compare the difference in filter operation and performance when filtering different effluents. Wastewater quality parameters used to monitor filter performance were biochemical oxygen demand (BODs) and suspended solids. The quality of filter influent affected the quality of the filter effluent. Typical total BOD 5 and suspended solids removal efficiencies were 30 percent and 75 percent, respectively. Soluble BODs was not significantly removed by granular filtration. iii The four filter beds were equally effective in removing suspended solids and biochemical oxygen demand. The coal layered filters operated for 22 hours maximum. The longest filter run time for the sand filters was 9 hours. Filtration of the Preston treatment facility effluent did not consistently produce an effluent that would satisfy the 10 mg/t BOD5 effluent discharge requirement. A survey conducted to review approval criteria and design standards for wastewater filters employed by state regulatory agencies indicated the following. t10st state standards allowed the installation of either gravity flow filters or pressure filters. The majority of state agencies base the allowable hydraulic loading rate on the type and configuration of media employed. The majority of the design standards for wastewater filters permitted the following media types:(1) sand; (2) anthracite; (3) sand and anthracite; and (4) sand, anthracite, and garnet or ilmenite. All wastewater filter design standards called for backwash appurtenances complete with air scour or mechanical scour. I NTRODUCT I ON . PURPOSE OF STUDY Specific Tasks Scope of the Study LITERATURE REVIEW Introducti on Theory Filter Types . Filter Rate Control Filtration Rate ~1edia and Depth Headloss and Run Length Filter Backwash .. . TABLE OF CONTENTS Biochemical Oxygen Demand and Suspended Solids Removal Influent Characteristics Filter Design . Pulsed Bed Filtration RESEARCH PROCEDURES Location. . Filter Column Design Fil ter r·1ed i a . . . • Operation of Experimental Filters Backwash. . . Water Sampling and Analysis RESULTS AND DISCUSSION General Influent Sources . Influent and Effluent Relationship Filter Media Performance BODs and SS Removal . Headloss Development Backwash. . . Filter Cycle Performance BODs Equation • Use of BODs Equation FILTER DESIGN CRITERIA SURVEY Types of Filters Rate of Filtration . 11edia Type, Size, and Depth Backwash . Summary SUMMARY1 CONCLUSIONS 1 SIGNIFICANCE 1 AND RECOMMENDATIONS Summary and Conclusions Engineering Significance Recommendations LITERATURE CITED APPENDICES APPENDIX A: Filter performance data from pilot-scale study conducted at the Preston Wastewater 3 3 3 3 4 4 5 5 5 6 7 7 7

Design of 90-mgd wastewater reclamation plant

Abstract: Ninety MGD of municipal secondary effluent is to be reclaimed for use as cooling water in the Palo Verde Nuclear Generating Station in Arizona. The water reclamation plant design criteria are presented for nitrification, lime-soda softening, filtration, and sludge processing. In-pipe storage is used for flow equalization. Forced air down-draft trickling filters with computer-controlled recycle are used for nitrification. Effluent recirculation is used to maintain constant sludge blanket dept in the upflow solids contact clarifier softening units. An influent flow-splitting, gravity-backwash, dual-media filter is used for final suspended solids removal. Rheological data was used in the hydraulic design of sludge piping. Computerized automatic flushing also aids in preventing sludge pumping problems. Reclamation plant design and construction are integrated in one Engineering-Procurement-Construction project conducted by a single company.

Process and device for treating waste waters by activated sludge and trickling filters

Abstract: A discrete quantity of elements having a nature comparable to that of a trickling filter, and preferably having a density similar to that of the waste waters, is fed in suspension into a tank and circulated there. The elements preferably comprise a cellular material, such as for example rubber, and are saturated with a slime-like mass. After leaving the tank, the elements are separated from the treated waste waters, regenerated and returned to the inlet of the tank.

The design of high-rate trickling filters

Abstract: Despite the considerable effort that has already been devoted to the study of trickling filtration, there is still no reliable equati for the design of high-rate trickling filters. Moreover there are a number of unresolved problems in the trickling filter literature concerning both theoretical and empirical aspects of the process. The major thrust of this work is to develop better methods for design; the theoretical and empirical discrepancies are considered in as much as their resolution affects design criteria.From a survey of the trickling filter literature, a large number of design models were reviewed and critically analyzed. The equations fall into three broad categories, empirical, semiempirical and mechanistic; of these the semi-empirical were selected for further critical analysis as they offer the greatest potential as useful design equations. Eight semi-empirical equations were tested with literature data from a number of full and pilot scale filters. Because of deficiencies in the available data, only limited conclusions could be drawn concerning the relative merits of each of the models for design purposes.In order to obtain better data, a pilot-scale study was undertaken with particular attention being given to:-(i) experimentation over a wide range of filter variables.(ii) attainment of steady conditions within the filter.(iii) the removal of insoluble, as well as soluble, wastewater components.The experimental study was carried out with one particular wastewater, that from a meatworks, but two pilot-scale filters were used, each at a different meatworks. As well as enabling better discrimination between alternative design equations, the results of the pilot study enabled the development of a design equation specifically for meatworks wastewater. The semi-empirical equations were then tested with the pilot plant data. The major result was that of the two-parameter equations, those based on simple, first order kinetics were found to be generally the-best for describing the behaviour of filters treating real, complex wastewaters, i.e. those with both soluble and insoluble components. For wastewaters with only soluble components, a model based on half order kinetics was more appropriate. A three- parameter, variable-order model offered some advantages over these models, but the advantages were outweighed by its extra complexity. A number of models previously developed for use as design equations were found to be occasionally or consistently unsuitable for design purposes.A first order equation was developed for designing high-rate filters treating meatworks' wastewater; it gave good agreement with published data. In addition, information for design of facilities for sludge separation and disposal was obtained during the pilot plant study.The effect of operating variables on filter behaviour was studied. Recycle was shown to have no beneficial effect on filter performance. The filter could withstand shock organic and hydraulic loads without any significant reduction in performance. This ability to handle shock loads indicated that high-rate filters are particularly suitable for partial, or roughing, treatment of wastewaters prior to further treatment. Considerations of the effects of hydraulic rate, depth of packing and influent concentration added further support to this conclusion.

Sewage pre:clarification system - with trickling filter re-cycling side-stream to sealing basin inflow

Abstract: A sewage pre-clarification system consists of a settling tank and a trickling filter which extracts a side stream from the tank outflow and feeds its run-off to the tank inlet. The trickling filter has a packing which exerts a biological action on the side stream; its sludge flocks add as collectors for the contents of the crude sewage. The advantages of the parallel connection of trickling filter and sedimentation tank instead of the conventional tandem connection results in an overall efficiency of 55-60% instead of the conventional 25-30%.