Sanitary Wastewater Research Articles

Use of peat in water pollution control: a review

Peat, besides being plentiful and inexpensive, possesses several other qualities that make it an effective medium for the removal of pollutants. This paper presents a review of its use in water pollution control — in the treatment of sanitary and industrial wastewaters. Key words: peat, water pollution control, wastewater treatment, onsite wastewater systems, industrial wastes.

Dimensioning of Combined Sewer System Detention Basins by Long Term Simulation of Storm Water Runoff

At present, dimensioning of combined sewer detention basins in Germany is based actually on the rational formula and on the idea of the existence of the so-called “first flush”. New measurements and recent investigations have led to the questioning of this dimensioning procedure. An alternative developed in this paper is based on the application a storm-water-runoff-model (hydrological and/or hydrodynamic) in each special case. Input to the model is a period of at least one decade of continuous rainfall data (long term simulation). The sanitary waste water component is superimposed to the simulated runoff-hydrograph. The first flush-effect is neglected. The dimensioning of a detention basin is based on the determination of several quantities such as number, duration, peak discharge and volume of overflow events in relation to the total water detention volume of the system. The decision on final dimensioning has to be made with respect to the characteristics of the receiving water.

Biological treatment of mixed industrial and sanitary wastewaters

The Enlarged Shuaiba Industrial Area of Kuwait contains the largest concentration of industries in Kuwait. The wastewaters from this area are, in the main, discharged into the Arabian Gulf after some pretreatment. In an effort to alleviate the pollution of the Gulf, laboratory-scale biological treatability studies were undertaken. A composite industrial wastewater representing the effluents from oil refineries and petrochemical plants, and domestic wastewater were treated by activated sludge and “Captor” reactor systems. Effective nitrification was observed in both systems. At the scale studied (5 1), however, the activated sludge system was found to be superior in performance. The poorer performance of the “Captor” system can probably be attributed to an accumulation of oil that inhibited the activity of the microorganisms within the sponges.

DESIGN OF AN INTERMITTENTLY OPERATED OUTFALL

The City of San Francisco, California, has a combined sewer system that presently overflows into the bay or ocean when it rains. Under the current wastewater management program being implemented, this combined flow of storm and sanitary wastes will be treated and discharged into the Pacific Ocean through a three-pipe outfall system. The system will dispose of the treated sanitary wastewater (dry weather flow) through a 2740-millimetre-(mm)-diameter, 6-kilometre (km) ocean outfall, and the mixture of sanitary wastewater and stormwater (wet weather flow) will be disposed of through two 2740-mm-diameter outfalls, 4 km long. The depth of the dry weather diffuser is approximately 24 m and the depth of the wet weather diffuser is approximately 17 m. The wet weather outfall will operate only when the rain exceeds 0.5 mm per hour. Rain exceeds this intensity about 4 percent of the time, or 350 hours per year. The peak wet weather flow is approximately 1800 megalitres per day (Ml/day)3. The average dry weather flow is 400 Ml/day and the peak dry weather flow is approximately 700 Ml/day. This paper reviews the unique problems of an intermittently operated outfall located in an area of shallow water with loose bottom sediments on a coast subjected to high wave energy. The circulation of seawater through the dormant diffuser and the resulting reduction in hydraulic capacity by sediment intrusion and biofouling are identified as the most severe problems for the intermittently operated outfall. The features incorporated to reduce these problems are bottom-exiting risers, diffuser ports elevated above the seabed, four ports per riser with a dual valve system, and use of antifouling materials and a flushing system.

The dual functioning swirl combined sewer overflow regulator/concentrator

A hydraulic laboratory pilot project was conducted in conjunction with mathematical modeling to refine and demonstrate the swirl flow regulator/solids-liquid separator. The device, of simple annular shape, requires no moving parts. It provides flow regulation with a central circular weir, and simultaneously treats combined storm and sanitary wastewaters with a swirl action, thereby achieving liquid-solids separation. The low-flow concentrate is diverted by a bottom orifice to the sanitary sewerage system for subsequent treatment at the municipal works. The relatively clear liquid either overflows the weir into a central downshaft and receives further treatment, or is discharged to the stream. The device is capable of functioning efficiently over a wide range of combined sewer overflow rates, and can effectively separate suspended matter at a fraction of the detention time required for conventional sedimentation or flotation. For these reasons, serious thought is being given to the use of swirl units as wet weather treatment plant systems.

The Dispersion and Detectability of Sanitary Waste-Water Discharges From Navy Ships

Assessing the impact of Navy shipboard sanitary waste discharges within the contiguous zone of the United States requires generation of data, not available so far, on the dispersion and fate of pollutants from shipboard sources. To generate data applicable to the 3–12-mi coastal zone, studies were conducted by the Naval Ship Research and Development Center using Naval facilities in the Norfolk, Va. area. Controlled releases were made of sanitary waste water and tracer dye mixtures. Dispersion of waste/dye patches was monitored through aerial reconnaissance, precise radio-navigational information, and seawater sample collection. It was demonstrated that pollution from controlled releases of sanitary waste can be detected above background concentrations for a brief span of time using conventional methods for determining effluent water quality (5-day biochemical oxygen demand, total suspended solids, ammonia-nitrogen, total acid-hydrolizable phosphate, coliform bacteria). A mathematical model for the dispersion of pollutants discharged from ships in the coastal zone was developed from these data. An assessment was then made of the concentration of pollutants after discharge from Navy ships during normal operation. Seawater samples were collected from the wakes of ships in transit and from the water around ships anchored for an amphibious operation in the coastal zone. It was determined that pollutants discharged from the transiting ships were not measurable above background concentrations, and only slight coliform bacteria population increases were detected in the amphibious operations area. These increases were still well within those prescribed as safe for bathing beaches and fisheries. Findings of this study specifically refer to the Navy ships and the geographic locations involved. They may be used for estimating effects of sanitary waste releases by non-Navy ships and in other areas.

Biological Denitrification and Phosphate Removal

The objective of this study was to evaluate the feasibility of a simplified system for processing sanitary wastewater for nutrient reduction, using a submerged filter, an aeration basin, a clarifier with the underflow returned to aeration, and an effluent recirculation line back to the filter influent. This three-step treatment process had several apparent disadvantages, with the most serious being the lack of research and development on submerged filters.

Development and application of the thin channel rectangular air lift mass transfer reactor to fermentation and waste‐water treatment systems

AbstractThe consideration of fermentation principles in the treatment of industrial and sanitary waste waters leads to substantial process improvements. In particular, the rate of reaction can be improved by several fold by establishing the proper environmental conditions for microbial growth in a fermentation system. Recent work on the concentric cylinder air lift has shown it to be an economical fermentor with many advantages over conventional fermentors. An attempt to improve the economical performance of this system led to the development of the thin channel rectangular air lift fermentor. This was based upon a theoretical analysis of performance parameters. The analysis indicates decreased bubble coalescence, increased bubble entrainment, decreased power costs, increased mass transfer coefficients, and decrease capital costs. Experience using a prototype thin channel rectangular air lift system with sanitary and industrial waste‐water treatment systems has demonstrated exceptionally high rates of BOD removal at low operating and capital costs.

Virus Removal and Inactivation by Physical-Chemical Waste Treatment

A prototype of a packaged sanitary wastewater treatment system employing physical-chemical processes was evaluated for its ability to remove and inactivate enteric viruses. The treatment system, consisting of comminution, chlorination, activated carbon adsorption, alum flocculation, and vacuum filtration using diatomaceous earth as a filter aid, was designed for a variety of situations where conventional biological treatment is impractical. Both simulated marine sewage and simulated river water to which vaccine strain type 1 poliovirus was added as a marker were used as influent wastewater. The treatment system was capable of reducing the total amount of virus in the wastewater from about 99.96% reduction when marine sewage was processed, and from over 99.9996% reduction when simulated river water was processed. However, about 2.6 and 0.16% of the total influent virus was detectable in filter cake solids from raw sewage and from simulated river water, respectively. The degree of virus reduction in the treatment system is superior to that obtained in conventional primary and secondary wastewater treatment.