A method for the analysis of refuse stability has been developed and tested by analyzing refuse obtained directly from test lysimeters and actual landfills across the United States. Refuse samples from test lysimeters are analyzed to develop the procedures and to test the concepts involved. Results obtained from actual landfill situations are compared to those obtained from the test lysimeters of known refuse age in order to determine the degree of refuse stability in each landfill in relation to depth and location. Each landfill was analyzed as to how environmental conditions such as pH, moisture content, and remaining organic content are affected by location and depth. Also, the results obtained from landfills of different geographical locations, different climatic situations, and different configurations are compared. Because the ultimate use of a sanitary landfill site is of prime concern, the rate of refuse stabilization is important to know from the standpoints of future leachate production, methane gas generation, and differential settlement.

The purpose of this laboratory study was to evaluate, and model the effect of solids retention time in the activated sludge process (θ_c^AS) on the performance of anaerobic digesters fed the resulting waste sludges. Activated sludge systems were operated over a range of θ_c^AS values, with the waste sludges used as feed sources for batch and semi-continuous anaerobic digestion studies. Previous models for aerobic biodegradability of activated sludges were found to accurately predict ultimate anaerobic digestibility. However, conventional kinetic models of digestion over-estimated actual performance with this substrate. An activated-sludge anaerobic digestion model is proposed which includes a first-order rate mechanism for preliminary conversion of viable activated sludge biomass into available anaerobic substrate. Decreasing θ_c^AS results in increased sludge solids for digestion. However, the solids are of sufficiently greater digestibility that both the quantity of digested solids for ultimate disposal, as well as the cost of digestion, are virtually independent of θ_c^AS.

Two solids inventory control strategies for prevention of clarification failure in the activated sludge process are considered. Recycle rate control is shown to be effective for a certain class of operational situations. This control algorithm, however, is not applicable to situations in which an activated sludge system is experiencing severe hydraulic surges. In such situations clarification failure can be effectively controlled only through the application of the step-feed strategy in which the location of the feed to the aeration basin is shifted downstream in a multipass basin.

Calcium carbonate was utilized to neutralize an acidic lake and stream in the Adirondack Region of New York state. Theoretical calculations based on aqueous base neutralizing capacity underestimated the CaCO₃ dose required to achieve lake neutralization (pH 6.5) for a year. It would appear that lake sediments have a profound influence on base dose requirements. Calcium carbonate neutralization altered water column pH, calcium, acid neutralizing capacity, dissolved inorganic carbon, dissolved organic carbon, free fluoride, aluminum, manganese, zinc, and copper levels. Chemical equilibrium models appear to be a useful tool in predicting changes in aqueous aluminum chemistry. While calcium carbonate appears to be an effective means of accomplishing lake neutralization, there are potentially deleterious consequences associated with its use.

Eight test lysimeters containing 100-200 tons of refuse each were monitored for seven years for leachate and runoff rates, leachate and gas composition, refuse temperature, and surface settlement. The lysimeters were designed to indicate the effects of refuse shredding soil cover, and lift thickness on the monitored parameters. More runoff but less evapotranspiration was obtained with soil cover, with the result that leachate rates were approximately the same with or without soil cover. Shredded refuse produced higher peak concentrations of matter in leachate than unprocessed refuse when landfilled under similar conditions. The absence of soil cover resulted in leachate strengths declining rapidly after peak concentrations were produced, with the result that shredded refuse without cover produced less COD than either shredded or unprocessed refuse which was covered. Doubling the depth approximately doubled the leachate COD levels, but greatly increased the stabilization time required to low COD levels to be attained. Placing a second lift of refuse over a relatively stabilized first lift resulted in 75 to 99% reduction in COD produced by the second lift.

The effect of compression resistance on terminal settling velocity results obtained from batch tests has been studied by means of dimensional and numerical analyses, and comparison with experiment. It is concluded that the Talmage and Fitch (single test) method is unreliable when compression effects are significant, because it only gives a satisfactory approximation when the terminal settling velocity - dilution relation is convex downwards, but whether this applies or not to the suspension under test cannot be determined from the tests. To determine whether compression effects are significant, repeat tests using different initial suspension heights are necessary, at least at the smallest dilution for which data are required. When significant effects are present, repeat tests (at each dilution) allow the corresponding terminal settling velocity and compressive stress values to be obtained from the intercept and slope of a plot of initial settling velocity versus reciprocal initial height (the Michaels and Bolger extension of the Coe and Clevenger testing procedure).

A stormwater runoff pollutant loading model has been developed on the basis of results from composite sampling of approximately 500 storms at nine locations in Washington State. One component of the model is an expression for total suspended solids (TSS) load in relation to traffic, runoff coefficient, and surrounding land use contributions. Other contaminants are estimated from TSS load using ratios derived from the data. These ratios may be taken as constants at any Washington State location for some pollutants or as linear functions of traffic for other pollutants. The model as presently constructed is capable of predicting loadings over a time span encompassing a number of storms (monthly or annually), but has little precision when applied to individual storms.

Tests have been conducted to determine the efficiency of and factors affecting extraction of semivolatile organic priority pollutants from solid samples using modified Soxhlet procedures. Test variables included time of solvent contact, particle size of solid matrix, and type of solvent. The results indicated that extraction efficiences varied substantially for different priority pollutants. The most important factor in obtaining maximum recovery seemed to be the contact time during extraction. Particle size had a minor bearing on extraction efficiency. Solvent losses contributed significant errors when using extraction times longer than 24 hours. When proper consideration is given to the extraction efficiencies and to other sources of error, the Soxhlet procedure is useful for providing estimates of the quantities of semivolatile priority pollutants in solids.

A review of state and local sediment control programs in North Carolina relative to urban and highway construction and sanitary landfill operations is presented. Law and institutional arrangements, operations and management, technology, economics, enforcement, education, and public acceptance are included. Emphasis is placed on erosion and sediment control as a part of project planning and design. Conclusions and recommendations for strengthened program are given.

Decentralization within metropolitan areas has been a major aspect of population movement in the United States over the past two decades. This trend has great significance for all urban service activities. In particular, it affects water supply planning in urban areas. Both numbers of people and their spatial location affect forecasting of water supply demands which, in turn, affect fixed plant investments (source works, treatment works, transmission lines, distribution systems, and so forth) which are frequently built many years in advance of the resulting services. This paper describes, via a case study, the use of population and per capita demands as a basis for forecasting water requirements. Water use is studied according to residential and nonresidential demand. These data, combined with extrapolated demand coefficients, can be used as the basis for demand forecasting that not only provides estimates of quantity of demand but location of demand as well.

Wet weather and dry weather sampling is utilized to monitor densities of coliform bacteria in waters draining residential areas of coastal North Carolina. The bacterial levels are compared to different densities of unsewered residences in each watershed and the limitations of the developed soils for assimilating septic tank effluent. An analysis of the data implicates septic tank drainfields installed in unsuitable soils as a major source of contamination of these shellfish waters. In order to reduce the threat to public health and the multimillion dollar economic loss to the fishing industry, several options are presented for rehabilitating concentrations of failing septic tank systems and for modifying overdesigned drainage systems that carry the contamination directly to shellfish waters. In addition, several common sense management practices that minimize the delivery of bacterial contamination to estuarine waters are suggested for use in siting future coastal residential development.

The use of activated carbon for heavy metal removal was exemplified by studying the adsorption characteristics of Cd(II) from Cd(II)-BF₄ plating solution on both granular and powdered activated carbons. The results indicated that at all pH values, powdered activated carbons such as Nuchar SA and Nuchar SN, exhibited greater Cd(II) removal capacity than the granular ones such as Darco HD 3000 and Filtrasorb 400. The powdered activated carbon was bound to spheres (0.6 mm-1 mm) using a suspension-polymerization technique. The adsorption capacity of the aggregated carbons was 85% - 90% of the unbound ones. The rate of Cd(II) removal at pH 7 is proportional to the cadmium concentration, the carbon dose, and the available surface sites. Used activated carbons were regenerated chemically with strong acids such as HCl, HClO₄, and H₂SO₄. Two treatment schemes are proposed with economical analysis for comparison with other common treatment processes.

The major solid waste produced at coal conversion facilities will be gasification slag or ash. To evaluate the impact of this waste on the environment, the Oak Ridge National Laboratory conducted extensive characterization and leaching studies on ash/slags that had been generated in bench-scale operations, pilot plants, and/or process development units for eight different gasification processes. These studies, designed to assess the consequences of disposal in landfills, showed that none of the leachates from these eight wastes exceeded the U.S. Environmental Protection Agency's toxicity limits. Thus, these ash/slags would be classified as nonhazardous wastes. Quantities of polynuclear aromatic hydrocarbons (PAH) that were observed in the aqueous leachates of selected ash/slags were less than 1 μg/g and appear to be of no significant environmental concern. Column elution studies revealed effluents with pH values less than three and sulfate concentrations greater than 10,000 mg/L for wastes containing sulfur concentrations from 0.3-4%. As a result, the major environmental impact associated with disposal of these solid wastes appears to be the dissolution of sulfate and the potential acidification of ground water.

A procedure for direct contact algal assay is described which provides quantitative data on phosphorus transfer from soil to algae in serial 14-day incubations. The algae/soil/liquid phases are in direct contact. The procedure requires no special equipment other than that specified for algal assays in the Selenastrum capricornutum Printz Algal Assay Bottle Test. The method is a multi-interval assay and, as a result, provides a higher and more realistic value for maximum algal available phosphorus than obtainable using single interval assays.

In certain biofilm processes, such as nitrification and anaerobic carbon removal, biofilm attachment and growth may take several weeks or even months. This research focuses on determining the effect of synthetic and naturally produced polymers, used as surface conditioners, on the rate of biofilm attachment and growth. Partial success was obtained, and the only practical alternative seems to be to precondition the surface of the media by growing an easy-to-develop biological film before the final biofilm is induced to grow. This paper also reviews the literature which describes the factors affecting the attached growth of bacteria.

Integrated operation was simulated of 10 dynamic combined sewer regulators on a Montreal interceptor. Generally, when no in-line or other in-system storage can be called upon, advantage over local automatic-dynamic regulator control cannot be obtained by integrated operation of regulators. This happens unless expected flowrates to the interceptors can be estimated in advance of their actual occurrence; or unless an operational bias is introduced. These either minimize overflows from only some of the regulators on an interceptor, or favors the timing of overflows from all of the outlets, such as during the initial storm period. Computations for an actual system covering a summer season indicate even when a time-varying pollutant parameter is accounted for, the reduction in mass of a pollutant entering the receiving water under integrated operation of regulators may be only marginal. The potential for pollutant reductions at designated outfalls, however, is promising.

The regeneration characteristics of five commercially available granular activated carbons with methanol were evaluated. Three of the adsorbents were bituminous base carbons, while the remaining two were manufactured from lignite coal and wood. The adsorbates were p-chlorophenol, and two-ring, four-ring and eight-ring azo dyes. The rate of regeneration of the five adsorbents appeared to be sensitive to the molecular weight of the adsorbate; decreasing with increasing molecular weight. During the methanol regeneration of the p-chlorophenol and two-ring dye, an upper limit for capacity recovery was observed for all adsorbents, suggesting that a maximum recoverable capacity has been obtained. This phenomenon was not observed for the remaining two adsorbates due to exceedingly slow extraction rates. The extraction efficiences obtained for p-chlorophenol and the two-ring dye were found to correlate with the adsorption energies of these adsorbates on activated carbon. The extraction efficiency was observed to decreased with increasing adsorption energy.