Modeling the Performance of the Intermittent Sand Filter

Several models were developed to predict the efficiency of the intermittent sand filter (ISF) in removing algae from wastewater stabilization pond effluent; volatile suspended solids (VSS) was the analytical technique used to identify algal concentrations. The first (ISF model) and second (modified ISF model) models consisted of two distinct portions: a surface algal layer (SAL) component and a sand phase component. In the ISF model, the sand phase component was described in terms of 20 empirical sand filter efficiency terms (20 ^ coefficients); in the modified ISF model, a functional relationship between ^ and filter depth was developed. The modified ISF model was less accurate than the ISF model in predicting filter effluent quality. The third model (simplified ISF model) consisted of a single component (the sand phase). The mass of algae which was deposited to the SAL componenet in the first two models was, instead, forced into the top (2 inch) layer of sand. The functional relationship between the sand phase filter term and filter depth was recalculated and utilized to desribe the decrease in the concentration of algae during the filtration process. The simplified ISF model was comparable to the ISF model in predicting filter effluent quality. The simplified model predicted 85 percent VSS removal for 0.17 mm effective sand size (E\u27) filters and 44 percent VSS removal for 0.40 and 0.68 mm E\u27 filters. The application of the simplified ISF model is subject to limitations of maximum hydraulic loading rates of 0.7 million gallons per acre per day and miximum mass loadings of 49 grams of SS per m^2 per day for 0.17 mm effective size sand. Design curves, in which period of filter operation was described as a function of mass loading, were developed for ISF systems containing 0.17, 0.40, and 0.68 mm E\u27 media. Wastewater stabilization pond effluents having calcium carbonate precipitation problems were included as a special case in this analysis

Detergent and Non-Detergent Phosphorus in Sewage

Introduction: Quantitative data on nutrient levels in sewage from homes which are using heavy-duty detergents and which have been restrcited from using such detergents is necessary before rational decisions on the removal of phosphorus from detergetn can be made. Furthermore, the effect of various standard sewage treatment schemes on phosphorus levels should be evaluated to determine the relative cost of such treatment. Then the cost (to society, the environment, and to the taxpayer) of phosphorus removal from detergent and/or from sewage effluents can be estimated and such data utilized to make the appropriate policy decisions. The report herein presented is concerned principally with developing basic data that will provide information as to the changes that occur in concentration, biostimulation, and phosphorus removal efficeincies with and without heavy-duty detergents

The Kinetics of Rotating Biological Contactors Treating Domestic Wastewater

Four, four-stage, laboratory scale rotating biological contactor (RBC) units were employed to develop kinetic models for the RBC process when treating domestic wastewater. The study was conducted at three different temperatures of 5 degrees C, 15 degrees C, and 20 degrees C. Each unit operated at a different constant organic loading rate taht ranged from 4 qCOD/m^2/d to 14 gCOD/m^2/d and at a constand detention time of 2 hours. Carbonaceous substrate removals measured as COD cencentrations with the four-stage RBC\u27s were 80, 85, and 90 percent for 5 degrees C, 15 degrees C, and 20 degrees C, respectively. The major part of the removal occurred in the first stages. The overall precentage removals of ammonia nitrogen were 87 to 98 percent at 15 degrees C from 91 to 99 percent at 20 degrees C depending upon the influent organic loading rate. At 5 degrees C there was no ammonia nitrogen removal. Kinetic models were devloped and kinetic constants were determined for COD and ammonia nitrogen removal in the first and succeeding stages of the RBC units. Biomass yeild, biomass stabilization, and ammonia nitrogen removal were also evaluated. Monod growth kinetics were used in the development of the models for carbonaceous substrate removal in the first stages and for ammonia nitrogen removal in the system. The temeprature dependency of each kindetic constant was determined for the range of 5 degrees C to 20 Degrees C. Steady-state kinetic models were developed, and kinetic constants were determined as a function of temperature to provide a rational design approach for the RBC process treating domestic wastewater

Development of Design Criteria for Sensitizer Photooxidation Treatment Systems

Sensitized photooxidation is a physicochemical process that can degrade many toxic and refractory organic pollutants. A trace quantity of sensitizer added to the waste absorbs visible light; electronically excited intermediates then transfer the energy to decompose the waste. Engeineering design criteria were developed for industrial waste treatment lagoons that would use sensitized photooxidation. Design criteria were developed regarding optimum lagoon pH, optimum sensitizer concentration, depth and sizing of lagoons, dissolved oxygen requirements, and effect of temperature on photooxidation rate. Treatment of the refractory pesticides bromacil, terbacil, and fluometuron was investigated using methylene blue and riboflavin as sensitizers. Methylene blue-sensitized photooxidation of the three pesticides was most efficient at basic pH. The optimum pH of riboflavin-sensitized photooxidaction varied and was substrate-dependent. A model was developed to predict sensitized photooxidation rate as a function of lagoon depth. The model is based on light intesnity, sensitizer extinction coefficient, and an applied quantum yeirld, all of which are integrated over wavelengths of visible light. The model serves as the basis of sizing photooxidation lagoons. A dissolved oxygen residual of 1 mg/1 was required to maintain maximum methylene blue-sensitized photooxidation rate. At least 4 mg/1 dissolved oxygen was necessary to maintain riboflavin-sensitized phooxidation at maximum levels. Oxygen uptake rates in sensitized phooxidation reactions were proportional to the concentration of substrate. Temperatures from 10 degrees to 35 degreees Celcius had no significant effect on sensitized photooxidation rates. Using the model developed, a methylene blue-sensitized phooxidation pilot lagoon was designed to treat a 30 mg/1 bromacil influent concentraion to 0.1 mg/1 bromacil in the effluent. For an influent flow of 0.263 m^3/min (0.1 MGD) waste, a 0.1 mg/1 methylene blue concentration, 36 cm depth, and 1870 m^2 surface area are required. A cost analysis was performed which indicated that sensitized photooxidation lagoons appear to be cost-compentitive with other industrial waste treatement systems

Evaluation of the Addition of Granular Media Filtration to Wastewater Treatment Plants to Meet New Standards

A dual media filtration study was carried out at the central Weber Wastewater Treatment Plant in Ogden, Utah, to evaluate its feasibility as a tertiary treatment to meet new effluent quality standards. A review of the literature indicated that dual media filters were more efficient than conventional single media sand filters because of the “in depth” filtration achieved by dual media filters. An experimental filter was operated at four different hydraulic loading rates, ranging from 3 to 6 gpm/ft 2 (122.10 to 244.20 1/min/m2), to evaluate its effects on effluent quality. Hydraulic loading rate was shown not to affect suspended solids removal. The experimental filter produced excellent suspended solids removal; however, BOD5 removal efficiency was relatively poor because the influent to the filter contained high concentrations of soluble BOD5 and colloidal organic solids. Filter effluent quality met State of Utah standards of 10 mg/1 of BOD5 at the hydraulic loading rate of 3 gpm/ft2 and exceeded the standard by less than 2 mg/1 at loading rates due to removal of 4, 5, and 6 gpm/ft2. Filter cycle durations were very short at higher filtration rates due to removal of influent suspended solids in the intermixed portions of the filter media. Biological growth within the filter media was a major problem in the operation of the filter. The filter influent was chlorinated to prevent this growth. The study indicated that dual media filtration of trickling filter plant effluent to meet new effluent quality standards is economically feasible and can produce an effluent which meets state and federal standards

V/STOL lift fan commercial short haul transports: Continuing conceptual design study

A design study of commercial V/STOL transport airplanes for a 1985 operational time period has been made. The baseline mission considered was 400 nmi at a cruise speed of M = 0.75 and a 100-passenger payload with VTOL. Variations from the baseline included mission distance, payload, cruise speed, and propulsion system failure philosophy. All designs used propulsion systems consisting of multiple gas generators driving remote tip turbine lift and lift/cruise fans. By considering the fan to be designed for operational reliability, significant simplication of the airplane systems and reduction in airplane size and cost can be achieved

Series Intermittent Sand Filtration of Wastewater Lagoon Effluents

Previous researches have found single stage intermittent sand filtration to be a feasible and economic means of upgrading wastewater lagoon effluent to meet future standards. However the major constraint on their use has been the length of the filter runs. Laboratory scale and pilot-scale series intermittent sand filtration of wastewater lagoon effluents has been found to substantially increase the length of filter runs as well as produce a high quality effluent able to meet future standards. Higher loading rates were round to be possible with series intermittent sand filtration. The operation consistently produced an effluent meeting present Utah “Class C” water quality standards for BOD5 (\u3c5 mg/l), and the operation also consistently met the 1980 Utah wastewater treatment plant effluent standard for suspended solids (\u3c 10 mg/l)

A Continuous Flow Kinetic Model to Predict the Effects of Temperature on the Toxicity of Waste to Algae

A continuous flow kinetic model to describe and predict the effects of temperature on the toxicity of a specific oil refinery waste to the green alga

Effects of Temperature on the Toxicity to the Aquatic Biota of Waste Discharges - A Compilation of the Literature

An extensive compiliation and general evaluation of the literature is presented which describes the temperature interaction with toxicity. Recent literature is summarized and made accessible along with a few generalized relationships such that researchers may design studies in a manner that will increase the utility of their results. A detailed indexing system is employed which makes the information contained in the report accessible by author, toxicant, and text organism. Summary tables of the most pertinent literature are also presented for easy subject retrieval. It was concluded that very little uniformity in experimental design is found between experiments on temperature-toxicity relationships, and a generalized summary of the results presented in th eliterature is essentially impossible because of the inconsistencies in experimental designs. The utilization of standard bioassay procedures is highly recommened, and these procedures should be applied to experimental designs which allow the estimation of parameters related to the theoretical effects of temperature

Review paper: Evaluation of Techniques for Algae Removal from Wastewater Stabilization Ponds

Introduction: Approximately 90 percent of the wastewater lagoons in the United States are located in small communities of 5,000 people or less. These communities, many with an average daily wastewater flow of only 175,000 - 200,000 gallons, do not have the resources to keep man at the lagoon sites throughout the day (38). A high degree of technical knowhow is usually lacking in these communities. Often only periodic inspection or maintenance is carried out by the general municipal work force. Therefore, the development of a relatively inexpensive method that does not require sophisticated and constant operation or extensive maintenance is needed to polish these effluents. Most regulatory agencies are adopting more stringent water quality standards, enforcement of which will necessitate changes in present treatment methods and the philosophy of wastewater treatment. Small communities utilizing stabilization ponds will be affected most drastically by new standards. Because most communities utilizing ponds are relatively small and installed ponds primariliy to avoid operating costs, it is unlikely that modifications requiring significant increases in operation will be acceptable. Therefore, the most sophisticated alternatives for upgrading treatment must be excluded from a practicable solution to solids removal from stabilization pond effluent