Showing papers on "Trickling filter published in 1989"

Enhancing reaction rates in nitrifying trickling filters through biofilm control

Abstract: Reaction rates in tertiary nitrifying trickling filters have been significantly increased by the development of the bio film-controlled nitrifying trickling filter (BCNTF). The use of cross-flow media in the BCNTF permits higher oxygen transfer to the biofilm than does the older vertical media. The use of a flooding cycle prevents the growth of predator organisms that have consumed the biofilm in other plants and disrupted nitri fication. A backwash feature controls biomass inventory and eliminates the need for subsequent clarification. Operation and maintenance and capital costs are often less than for other pro cesses. A design model has been developed that accurately predicts performance. / Water Pollut. Control Fed., 61, 618 (1989).

Fixed-biofilm reactors applied to waste water treatment and aquacultural water recirculating systems

Abstract: Fixed-biofilm waste water treatment may be regarded as one of the oldest engineered biological waste water treatment methods. With the recent introduction of modern packing materials, this type of reactor has received a renewed impuls for implementation in a wide field of water treatment. In this thesis the possibilities are presented for fixed-film post-treatment of anaerobically digested domestic sewage and water reconditioning in aquacultural water recirculation systems. Emphasis is put on the nitrification process and removal processes for organic matter, using the ½-order/0-order kinetic model for fixed-biofilm processes as a starting point for the research. With regard to waste water treatment biofilm COD removal kinetics for waste water, containing both suspended and dissolved organics, are discussed illustrating that the apparent kinetic order of the combined process and the reaction constant strongly depends on the ratio of suspended/dissolved COD. The overall conclusion was that a rotating biological contactor is especially suitable for this application, and that such reactor may be regarded as a reactor in which biochemical oxidation of dissolved organic substrate is combined with adsorption/flocculation processes of suspended organic matter. The suitability of fixed-film reactors for application in aquacultural recirculation systems is demonstrated by the implementation of a nitrifying trickling filter in a pilot-scale recirculation system for the culture of the African catfish. The corresponding design philosophy behind this system is based on combining the waste production dynamics in the fish tank with the waste removal kinetics in the trickling filter. Attention is paid in this design philosophy to a) hydraulic loading of the primary clarifier, b) dimensions of the fixed-film reactor, c) water recirculation rate, and d) water exchange rate. Refinements of the presented design philosophy can be found in anticipating the effects of simultaneous COD loading, dissolved oxygen levels, pH and salinity, which are discussed in separate chapters of this research. It is concluded that the specific information generated in this thesis may be regarded as a valuable contribution to a more rational approach in design and operation of aerobic fixed-film reactors in the field of water treatment, as compared to the conventional, largely "folklore-based" approaches.

Recombinant DNA in wastewater: pBR322 degradation kinetics

Abstract: Despite intense interest in recombinant DNA and the environment, no published studies have examined the fate of recombinant DNA in wastewater. We have determined the kinetics of breakdown of pBR322 in a two-stage standard rate trickling filter plant. Samples were taken from four points within the plant (influent, primary clarifier, final clarifier, and effluent) and mixed with plasmid in vitro. No DNA has been released into the environment. Agarose gel electrophoresis was used to determine the conformational state of the plasmid

The algae occurring in an uncovered trickling filter of a sewage treatment plant in Cracow

Abstract: The blue-green algae, green algae, and diatoms accompanying the sewage bacteria and fungi are listed. The mass occurrence of some species coupled with the simultaneous recession of others causes the surface of the filter to change colour

Nitrification of activated sludge effluent in a cross-flow medium trickling filter system

Abstract: Sludge from a treatment process using iron was exposed to a mildly acidic solution to investigate iron hydroxide's capacity to collect metals from waste. Batches of iron hydroxide were regenerated and reused 50 times to treat both synthetic and real plating waste. Treatment efficiency was very high and steady, and there was no indication of deterioration in any aspect of process performance. Over time, the treated metals were concentrated in the regenerant solution and may be recoverable. The acid and base requirements were comparable to those for conventional coagulation. Overall, the process appears promising for metal treatment, sludge minimization, and possibly metal recovery. J. Water Pollut. Control Fed.. 61, 481 (1989).

Process and apparatus for the biological and physical purification of waste waters

Abstract: In the process according to the invention, the waste water (effluent) - if necessary mechanically prepurified - is treated by biological trickling filter purication, if necessary aerated, flocculated and allowed to sediment, then the sedimented sludge or a part thereof - preferably mixed with waste water - with or without aeration is returned upstream of certain operations - with the exception of sedimentation - and the residual sludge and the purified water are discharged from the process. The process is characterised in that the flocculation is carried out, separately from the other operations with respect to time and place, up to a period of 5-30 minutes, preferably 15-20 minutes, at an average velocity gradient of 10-70 s , preferably 20-50 s , and furthermore the waste water and/or the sludge are/is aerated for a period of 5-40 minutes, preferably 10-15 minutes, based on the inflowing waste water rate. The process is characterised according to the invention in that it [lacuna] purifier (1) furnished with trickling filter, if necessary aeration and sludge aeration space (2, 5) and aeration apparatus (6.2, 6.5), settler (4), if necessary recirculation circuits (18, 17.1, 17.2) for the purified waste water and/or the sedimented sludge, and upstream of the settler... Original abstract incomplete.

Geothermal energy applications in wastewater treatment

Abstract: An evaluation was conducted on the use of geothermal energy in wastewater treatment in the Canadian Prairie Provinces. The assessment included an analysis of geothermal energy costs, an examination of the effects of using elevated temperatures in wastewater treatment, a selection of suitable uses of the low-grade energy in wastewater treatment, and a preliminary assessment of costs and benefits. By heating the wastewater influent to 30°C on a year-round basis, performance (as measured by BOD removal) of an activated sludge plant might be increased by 10–15%. There may be much less benefit in the case of long-detention aerated lagoons. The benefit may be significant (approximately 30%) for trickling filter plants, but such systems are generally not considered for use in the harsh western Canadian climate. The economics of using geothermal energy to improve wastewater treatment-plant efficiency is not particularly attractive. An additional investment of 33–50% of the cost of the treatment plant is generally required for the installation of a geothermal energy system so that any enhanced efficiency of the treatment plant is obtained.

Treatment of waste water in trickling filter

Abstract: PURPOSE:To increase the area of contact of waste water with microorganisms by backing the body of a trickling filter with a filler having a specified sp. gr. and by trickling the waste water on the filler to treat the waste water. CONSTITUTION:The filter body 11 of a trickling filter 10 is packed with a filler 12 and waste water 13 is uniformly trickled on the filler 12 with a trickling device to obtain treated water 14 from the bottom of the filter body 11. The sp. gr. of the filler 12 is regulated to <=1.0 and the diameter to about 1-10mm. While the waste water 13 passes through a layer of the filler 12 as a downward flow, org. matter in the water 13 is biochemically degraded by microorganisms growing on the surface of the filler 12 to purify the water 13 and the water 13 is discharged from the bottom of the filter body 11 as the treated water 14. Thus, blocking can be prevented.

Biological Phosphorus Removal Using a Fixed and Suspended Growth Combination: A First Year Appraisal

Abstract: As an alternative to the activated sludge process for biological phosphorus removal, this paper discusses an alternative which avoids high costs of air supply and large suspended growth tankage, a combination of fixed growth reactors (trickling filters) and suspended growth reactors was developed. The combination is believed to provide an improved environment for the biological phosphorus, carbonaceous, and nitrifying microorganisms. The 1.2 mgd treatment plant in Salmon Arm, British Columbia, Canada, has operated for almost one year in either of two modes of the four possible modes of plant operation. Examination of effluent concentrations of BOD 5 , suspended solids (SS), phosphorus and ammonia nitrogen has been undertaken during this time, and results are discussed.

Full Scale Performance of Primary Settling Tanks

Abstract: M.Murad, Senior Chemist Sewage Treatment Works Doha, Qatar The characteristics and the flowrate of municipal wastewater from the city of Doha, located in the Arabian Gulf have been studied to examine their effect on the performance of the primary settling tanks at the local sewage treatment plant. The wastweater is predominantly domestic and characterized by low suspended solids concentration but high total dissolved solids. The high temperature of the wastewater and long flowtime in the sewerage system turn it septic. The performance efficiency of the circular primary settling tanks in terms of total suspended solids and BOD removal was determined. Simple empirical models relating the suspended solids removal efficiency with various loading parameters like detention time, overflow rate and solids loading rate have been developed. The solids loading rate seems to be more significant than the overflow rate or the detention time in predicting settling performance. The results of the investigation are compared with published data. INTRODUCTION The wastewater treatment plant in Doha serves a population of about 250,000. The raw wastewater characteristics and the flowrate during different months are summarized in Table 1. The plant is divided into an old section and a new section. On average, three-fourth of the total quantity of wastewater flows to the new section and the remainder to the old one. In the old section the wastweater is given preliminary and primary treatment followed by trickling filters. After