Showing papers on "Trickling filter published in 1980"

Selected organic pesticides, occurrence, transformation, and removal from domestic wastewater.

Abstract: Chlorinated hydrocarbon pesticides (chp) and chlorophenoxy herbicides (cph) are two groups of compounds that have contaminated the aquatic environment as a result of their widespread usage and persistence. Measur able concentrations of chp and cph have been detected in the nanogram per litre to the microgram per litre level in almost all major U. S. rivers and lakes.1-5 One of the potential sources of chp and cph for natural waters is domestic wastewaters. From a literature review it is apparent that studies concerned with the effectiveness of conventional and advanced wastewater treat ment processes in removing organic pesticides are few, with the result that very little is known today about the ability of wastewater treatment processes such as activated sludge or trickling filters to remove these pesticides and herbicides. This paper presents a study performed on the occurrence, transformation, and removal of chp and cph from Dallas, Tex., municipal wastewater. A 3 785-m3/d (1-mgd) water reclamation pilot plant was used for this study. The pilot plant, built in 1969 by the city of Dallas, was designed to study the effectiveness of different sequences of unit processes in producing high quality effluent and includes two completely mixed activated sludge units (aeration basins and final clarifiers), a chem ical treatment module, two mixed-media filters, and two activated carbon columns. The in fluent to the pilot plant was derived from three different points in Dallas' White Rock Waste water Treatment Plant (WRWTP): second stage filter effluent prior to final clarification, final effluent prior to chlorination, and primary effluent. WRWTP is a 204 000 m3/d (54-mgd) high-rate, two stage trickling filter facility. From 1972 to 1975, a research program was conducted to investigate the feasibility of wastewater recycling processes. Active par ticipants in this program included the civil engineering department of Texas A&M Uni versity, the Dallas Water Utilities, and the U. S. Environmental Protection Agency (EPA). The pilot plant was operated with varying sequences of units processes, and samples from each treatment unit were subjected to an ex tensive analytical program. The analytical program included, in addition to chp and CPH, heavy metals, nutrients, viruses, and all the common water and wastewater control parameters such as pH, alkalinity, biochemical oxygen demand (bod), chemical oxygen de mand (cod), and suspended solids (ss). The study of chp and cph represents only one aspect of a broad research program designed to evaluate the performance of different se quences of unit processes. The results pre sented in this paper include the characteriza tion of domestic wastewater in terms of chp and cph and an evaluation of the effects of the activated sludge process on these com pounds. The effects of chemical and physical

Trace organics removal by advanced wastewater treatment

Abstract: A statistical study was performed on data on trace organics removal at an advanced wastewater treatment plant in southern California. The log normal distribution was used for the statistical analysis. Among the substances investigated were: chemical oxygen demand, chloroethanes, chlorobenzenes, chloroethylenes, naphthalenes, xylenes, methylphthalates, butylphthalates, polychlorinated biphenyls, and lindane. Data for the period in which trickling filter effluent was the influent to the plant indicated removals of 90% or more, with small confidence intervals. During a period when activated sludge effluent was the plant influent, confidence intervals were wider; generally the quality of influent water improved but changes in advanced treatment effluent quality were variable.

Land Treatment of Municipal Wastewater in Small Communities

Abstract: A sizable portion of the budget in many small communities is devoted to the treatment of wastewater (more commonly called sewage). A community of 5,000 persons may spend more than $150,000 annually (adjusted to a June 1978 base) for secondary wastewater treatment using trickling filters, a lowcost alternative for this size community. If, in addition, advanced wastewater treatment (AWT) is required to remove nutrients, such as phosphorus and nitrogen, in order to meet surface water quality standards, annual costs can increase to $391,000 and $443,000, depending on whether treatment techniques such as lime addition and nitrificationdenitrification are used (Young 1978). These processes can remove approximately 90% of the phosphorus and nitrogen, respectively, in municipal wastewater. As national policies to improve the quality of surface waters are implemented, increasing numbers of small communities in rural areas are being required to increase the level of treatment to include AWT. Research reported in this article shows that land treatment (LT) of municipal wastewaters can meet these increased surface water

Small=scale biological sewage treatment - with buffer basin, trickling bed filter and automatic recycling control

Abstract: A biological small-scale trickling filter bed plant for domestic sewage consists of a buffer basin upstream and two clarification basins downstream of the filter. Recycling of part of the outflow is automatically controlled by a float valve on the buffer basin. Adjustable orifices control the outflow of filter and second clarification basin. Such a plant is suitable for compensating for the non-uniform rate of sewage input. It requires only one pipe for the effluent leading to the seepage disposal area. The benefits of biological purificn. are thus available for smaller housing estates.

Efficiences of Advanced Waste Treatment Obtained with Upgraded Trickling Filters

Abstract: Many or most cities and towns, and particularly the smaller ones, still use trickling filters in their wastewater treatment plants. The process is economical and reliable, but unfortunately BOD\d5 and suspended solids removal efficiency in many cases is not high enough to meet today’s effluent quality requirements. But recent experience at Corvallis, Oregon, suggests that trickling filter plants can be upgraded, at relatively low cost to provide effluents of quality equal to advanced secondary treatment or even of advanced waste treatment (effluent BOD\d5 and SS less than 10 mg/l). Because of its relatively low cost and potential broad applicability, the innovation is thought to be very significant.

Biological waste liq. treatment - by oxygen enrichment before entry in trickling filter tower

Abstract: The Parent Patent No. 2746648 described a biological purification system for waste liquids and gases in a tower, filled with a packing of plastic elements where the quantity, temperature and concn. of the injected oxygen are adjustable. The oxygen is introduced to the packing elements through the waste liquid which has been enriched with oxygen before its entry. A repeated circulation of oxygen through the liquid results an oxygen economy. The permits a supersaturation of the waste liquids with oxygen so that the physiological capacity of the microorganisms and the efficiency of the treatments are improved, even for wastes which are very difficult to clean.