Wastewater Treatment Units Research Articles

Nitrification of swine waste

Complete oxidation of ammonia nitrogen (approximately 1000 mg/L) to nitrite was observed in stabilized swine waste after 49 days in incubation at 400 rpm and 29 degrees C, only if 10% (v/v) activated sludge from a wastewater treatment unit and 1.5% (w/v) CaCO3, were added. Stabilized swine waste contains less than 0.09 most probable number (MPN) per millilitre of nitrosobacteria and 2.3 MPN/mL of nitrobacteria. In activated sludge, the concentrations of these bacteria were 2.4 MPN/mL for nitrosobacteria and 4.2 x 10(5) MPN/mL for nitrobacteria. In the swine waste where ammonia was oxidized to nitrite, the nitrosobacteria growth increased to 5.5 x 10(5) MPN/mL, while the nitrobacteria growth decreased to 2.3 MPN/mL. Inoculation of a freshly stabilized swine waste with 10% (v/v) of the active nitrifying waste and addition of 1.5% (w/v) CaCO3, accelerated the oxidation of ammonia nitrogen to nitrite; the reaction was completed after only 5 days of incubation. Increasing the incubation period to 10 days resulted in the complete oxidation of the accumulated nitrite to nitrate. In the stabilized swine waste, complete nitrification without accumulation of nitrite was obtained in only 5 days of incubation when the waste was inoculated with both enriched nitrifying populations (10(6)-10(7) MPN/mL).

Der Entwicklungsstand der Hochtemperatur‐Verbrennung und Rauchgasreinigungstechnik — dargestellt an zwei laufenden Bauvorhaben

AbstractState of development of high‐temperature combustion and flue gas purification — illustrated for two current construction projects. The state of the art in rotary furnace combustion plant is described with the aid of two current construction projects for a chemical plant and for a publicly accessible plant. The concepts of the plant are adapted to the waste material to be disposed of, the energy utilisation system, and disposal of the residual materials. Data for the chemical plant indicate higher concentrations and fluctuations in the flue gas constituents. Flue gas scrubbing is accomplished here by quenching, passage, through two rotary scrubbers, and wet electrofiltration. Scrubber liquid is passed to a company purification plant. In the other case, no waste water may occur. A two‐field electrofilter and a two‐stage milk of lime washer are employed. Washing liquid is passed to a waste water treatment unit with vacuum evaporation. Special process engineering measures are necessary to maintain pure gas values even in cases of pronounced concentration fluctuations. Household and special waste incineration are discussed increasingly from the viewpoint of NOx reduction. Possible developments of SCR processes up to use of activated charcoal final purification stages are considered.

Biological Aerated Filter Evaluation

The paper presents the results of a two-year evaluation of a two-cell, full-size biological aerated filter wastewater treatment unit with a nominal flow capacity of 1893 m³/day (0.5 MGD). One cell was operated at a lower loading to accomplish combined biochemical oxygen demand (BOD) removal and nitrification, while the other cell was operated at a higher loading to achieve only BOD removal. The media size was found to be a critical design parameter for the system and was increased in each cell during the course of the study to allow 24-hour or longer run times before head loss levels required backwashing. The effluent BOD and suspended solids concentrations were related to the soluble BOD volumetric loading and reactor temperature. At relatively low organic and ammonium nitrogen loadings, up to 88% nitrification was achieved. Oxygen utilization efficiencies ranged from 5.0–7.7% for acceptable air application rates. Equations were developed to predict oxygen consumption and sludge production as a function of influent soluble BOD and suspended solids to influent total BOD ratios. The oxygen consumption was lower and sludge production was higher, compared to conventional activated sludge treatment. Useful design and operating parameters are identified for future evaluations of Biological Aerated Filter systems.

Mineralogical characteristics of residues produced in microbiological treatment of acidic mine drainages

Abstract Inorganic residues produced on the disks of rotating biological contactor (RBC) wastewater treatment units during microbiological oxidation of the ferrous iron in both natural and synthetic acidic mine drainages were analyzed using x‐ray energy‐dispersive microanalysis, x‐ray diffraction, and scanning electron microscopy. The predominant mineral forms were x‐ray amorphous ferric hydroxysulfates. In addition, jarosites were detected in RBC units which treated natural mine drainages, and magnetite was detected in solids generated during treatment of a synthetic acidic mine drainage. Bacteria were observed on the surface of the inorganic residues and in gelatinous films seen microscopically following chemical dissolution of the iron crust.

Hydraulic Analysis of Model Treatment Units

Rational guidelines for designing studies to improve an existing water or wastewater treatment unit configuration through the use of experimental analysis of small-scale models are presented. Tracer data results from a prototype and model chlorine contact unit are analyzed to develop and illustrate the main principles. These data show that nonreproducible tracer parameters can result if the model unit is only operated at a level prescribed by a dimensionless number such as a Froude number. It is also evident from these data, that indices commonly recommended for tracer analyses have varying degrees of reliability and should therefore be examined thoroughly for each model study.

F 2 Coliphage as Tracer in Wastewater Basin

In an effort to find a suitable tracer to determine virus flow-through in a sedimentation basin, the f2 coliphage was selected. This note demonstrates that the limitations of a biological tracer are no more serious than those of chemical tracers normally used. An example of the use of f2 coliphage as a tracer is provided. During a virus study determining flow-through time at a wastewater treatment unit, using the f2 coliphage as a tracer is shown to be convenient and its use is accomplished with little difficulty.