BOD Test Research Articles

Probable causes for reduced BOD test results in hypersaline wastewaters

The causes for erratic BOD results from wastewaters containing elevated concentrations of salt were investigated. Standard organic solutions and an industrial waste were tested with sewage seed and known species of salt tolerant bacteria using standard and hypersaline dilution water at three salt concentrations. Significant BOD differences were found when saline wastes were diluted with standard (non-saline) BOD dilution water. Bacterial populations to genera were monitored and it was shown that equivalent numbers of bacteria did not have the same capability to degrade a given amount of waste with increases in salt concentrations to the 3% level. Seeding of hypersaline wastewaters with known salt tolerant species is recommended for consistent BOD results.

Bio-refractory index for organics in water

This paper presents a method of classifying specific aquatic borne organic materials according to degradability. Laboratory procedures and rationale are given for the development of a parameter referred to as the Refractory Index (R.I.). Examples of refractory index values and significance are offered. Representative data are below for which there is roughly a 13% relative error for each R.I. value. Materials characterized as refractory (having a low R.I. value) are persistent for the conditions stipulated in the ultimate BOD test and therefore low R.I. indicates persistence in the water environment. Materials having low R.I. values should not be discharged in receiving waters unless extensive examinations show that the material can be effectively removed by treatment or does not cause harmful effects in the aquatic environment.

LABORATORY CONTROL OF EFFLUENT

Detailed practical information is given on procedures for sampling dairy effluents, sampling equipment and sampling errors. Laboratory testing methods described in detail include the BOD test, COD test and rapid COD test, solids content, organic carbon and total nitrogen. Information derived from each test, testing errors, errors of single composite samples and interpretation of results in relation to dairy losses is related to practical dairy operation and management.

Oxygen Utilization in Bacterial-Protozoan Community

A mathematical model for nutrients, microorganism growth, and oxygen utilization is developed and compared with experimental results using a population consisting of a bacterium and a protozoan in a carbohydrate limiting media. The model accounts for various biological contributions to the oxygen uptake, and the microbial interactions which occur within the bacterial-protozoan culture. The model and the experimental results have been used to explain the plateau frequently observed during the BOD test. The results of this study are also useful for defining the organic matter regeneration components of large multigroup ecosystem models.

GOALS IN WASTEWATER TREATMENT1

ABSTRACTWithin a few years all domestic wastewater effluents in the United States will be subjected to a minimum of a properly operated primary and secondary treatment process. This implies a very high degree of removal of the more readily biologically degradable material as measured by the BOD test. This practice will to a large degree negate the value of the BOD test as a pollution parameter. Organic carbon appears to be a more suitable means for determining the strength of a wastewater or for controlling the operation of physical and chemical treatment processes. Studies were conducted to determine the effect of time of passage on the ratio of organic carbon to BOD, COD and carbohydrate. The ratio was found to vary with both time and the state of the sample. The carbon content was reduced to a lesser degree than the other parameters. Organic carbon content appears to correlate better with COD than with BOD. The efficiency of a chemical precipitation process can be determined on the basis of organic carbon removal.

Biokinetic Evaluation of BOD Concepts and Data

The current techniques for analyzing BOD test data are considered and their inadequacies are pointed out. The paper deals primarily with a consideration of the BOD test as a process and with a definition of the components and details of the process. The three sequential components of the process are defined as bacterial utilization of substrate, protozoan consumption of bacteria, and autodestruction. Mathematical models are presented for evaluating each of these components and the methods of applying them are presented.

Hog Waste Disposal by Lagooning

A two-year field investigation and laboratory testing program has proven that a modified anaerobic lagoon can be used successfully for the disposal of confinement-fed hog waste. A loading rate of 275 feeder hogs per acre at an average depth of 5 ft provides for odor-free operation with a minimum of maintenance and a long operational life. The total containment design without an overflow or discharge eliminates the necessity for a receiving stream or secondary treatment but may require a special make-up water source. The system uses single stage anaerobic digestion (liquefaction) combined with a massive heterotrophic growth of algae (Chlorella sp.). A by-product, harvested algae for use as a feed additive, is an indicated possibility. Other included design factors are the chemical constituents and fertilizer values of hog waste. An interesting side-effect is the measurable antibiotic action of the waste caused by a carry-over of antibiotics from the feed. This was found to completely prevent digestion of undiluted waste and caused complete failure of the 5-day BOD test.