Showing papers on "Trickling filter published in 1988"

Occurrence of thermophilic campylobacters in sewage and their removal by treatment processes

Abstract: Removal of thermophilic campylobacters from sewage at three different stages of treatment at a trickling filter sewage works has been assessed. Samples of incoming sewage, primary sedimentation effluent and final effluent were taken daily from 06.00 h to 20.00 h for 5 consecutive days and the numbers of campylobacters determined by using a most probable number method. Each sample was cultured using 2 h pre-enrichment followed by enrichment in Preston broth for 48 h and detection by plating. Over 78% of the incoming campylobacters were removed after primary sedimentation and less than 0.1% remained in the final effluent. Campylobacter jejuni biotype I and biotype II constituted 81.5% and 15.9% respectively of the 232 isolates tested. Serotypes common in sewage were common in human faeces. It appears that the trickling filter sewage works removes most of the campylobacters entering the sewage works, but large numbers, estimated to be approximately 10(10), are released into the environment daily from a local sewage works.

Treatment of leachate from a solid waste landfill site using a two-stage anaerobic filter.

Abstract: Raw leachate was treated using a two-stage upflow anaerobic filter process. Leachate from a solid waste landfill site, which received both municipal and industrial wastes, contained high organic matter (17–21 g/L COD, 13–14 g/L BOD, and 3.5–4.6 g/L volatile acids), and low metal (Zn and Fe) concentrations. Depending on sampling time, leachate composition and characteristics varied considerably. At an organic loading up to 4 g COD/day2 media area, the BOD and COD removal percentages were 98 and 91%, respectively. The biofilters were also effective for metal removal. However, the filter effluent contained a high concentration of ammonia. System overloading was characterized by the accumulation of large quantities of volatile acids and by a now ratio of alkalinity/volatile acids, resulting in low COD removal and reduced gas production. Once the first filter was upset, the second stage could only partially respond to the volatile acids accumulated in the effluent of first filter.

Trickling filter for purifying waste water

Abstract: The trickling filter for purifying waste water (effluent) by nitrification and denitrification comprises a plurality of layers, each layer (2) comprising a material which is highly permeable to air, and a following layer (1) made of a material which is sparingly permeable to air, and these layers being arranged alternately.

Unit process tradeoffs for combined trickling filter and activated sludge processes

Abstract: Evaluation de systemes combinant des lits bacteriens et des processus de boues activees utilisables pour l'epuration biologique d'eaux usees

Wastewater treatment in low cost bamboo trickling filters and pond systems

Abstract: In Java, two low-cost bamboo trickling filters and a wastewater pond system were constructed and applied for two years for the secondary treatment of municipal wastewater. These systems were installed to provide a reduction of health hazards, caused by noxious organisms and ingredients of the wastewater, to a non critical level for a subsequent recycling of the wastewater by irrigation on paddy fields. The studies detailed here were aimed at the examination of the purification efficiency and process stability of each system and the evaluation of the utilization rate of the wastewaters ingredients. The cost benefit analysis gained low specific capital cost for each wastewater treatment system. A level of less than 20 US-Dollar per capita has been achieved at a small design population of about 20 capita. The data of these probe studies indicate that both the pond and the bamboo filter system can be applied as small scale wastewater treatment plants. The preference of these systems depends on local settings. In densely populated or mountainous regions the advantages of the bamboo filter systems outweigh those of the pond system. In regions abundant in water resources the pond systems should be preferred.

Development of a Rational Approach to Trickling Filter Design

Abstract: Trickling Filtration, like other biological waste-treatment processes, is an engineered development of a natural process of biodegradation. However both the design and operation of this process for municipal sewage—treatment are still somewhat empirical. In the case of industrial wastewater treatment the design situation is even less satisfactory. The basic processes which occur during the trickling filtration process are: (a) Mass transfer (of the organic material to be removed, plus nutrients and oxygen) into the slime and, (b) Biodegradation in the slime. These fundamental processes were studied under carefully controlled laboratory conditions by measuring the biodegradation of substrates using thin layers of heterogeneous microbial cultures. The commonly-accepted basis of the design equations found in the literature for trickling filters is a correlation of substrate removal in terms of some measure of the applied loading. The studies carried out show that this conventional procedure is unsound. An improved procedure which is both simple to use, and conceptually satisfying, is proposed.

Evaluation of power economy characteristics of aerobic wastewater treatment processes

Abstract: The relationship between the power economy and the BOD removal rate per unit floor area or unit volume of the aerobic wastewater treatment processes, such as activated sludge, trickling filter, rotating biological contactor, fluidized bed, oxidation ditch, deep shaft aerator were investigated under their conventional operating conditions for the domestic wastewater treatment. It was clarified that the higher BOD removal rate per unit volume or unit floor area of the plants brings about the lower power economy. Appropriate selections of wastewater treatment processes and their operating conditions are significant to maintain the high quality effluent and the high power economy.

The Trickling Filter/Solids Contact Process: Application to Army Wastewater Plants

Abstract: : More than half of the Army's wastewater treatment plants use trickling filter technology to provide secondary treatment. With the growth in regional population at many installations, there is concern that trickling filters alone may not be able to handle the additional loads generated. Moreover, this form of secondary treatment will need to be enhanced in order to produce an effluent meeting stricter environmental regulations. Several add-on and replacement techniques recently have emerged for trickling filter systems. These methods have reinforced the role of trickling filters in providing effective, economical secondary treatment. On particular interest to the Army is the trickling filter/solids contact (TF/SC) process. This method has some advantages over competing technologies, offering improved effluent quality, simple, reliable operation, low maintenance, and cost-effective treatment. The TF/SC process was evaluated for its feasibility in retrofitting Army wastewater treatment plants as well as for potential use in new construction. Information was taken from the current literature, field surveys, and site visits to operational plants.

Effects of primary effluent filtration on trickling filter design and operation

Abstract: The BOD associated with the suspended solids in effluents from primary clarifiers represents a substantial portion of the organic load applied to subsequent wastewater treatment processes. Recently, specially designed filters have been developed to deal with the problems associated with the filtration of primary effluent. An example of these filters is a fine‐grained, shallow‐bed, air‐pulsed filter. This filter has been applied successfully to treat primary effluents at a number of locations. Average suspended solids and BOD5 removals have been reported to be 50 to 70% and 25 to 45%, respectively. The purpose of this paper is to present information on how the use of primary effluent filtration may alter the design and operating characteristics of trickling niters, and to present a methodology which may be used to estimate the effects of primary effluent filtration on trickling filter performance.