The process performance of a down-flow hanging sponge (DHS) reactor for treating low strength sewage (biochemical oxygen demand (BOD) 20–50 mg/L) was investigated in Bangkok, Thailand. The hydraulic retention time (HRT) was set at 4 h during the start-up period and was reduced to 1.5 h in a stepwise manner. Throughout the 300-day operational period, the DHS reactor shows high performance with respect to the removal of total suspended solid (>90% total suspended solid removal efficiency). No clogging of sponge media was observed in response to the self-digestion phenomena of the biofilm. At a HRT of 1.5 h, the BOD removal efficiency was sufficiently high (about 85%). The pathogen Escherichia coli and other coliform bacteria were removed almost completely as well (removal was 99.4% and 98.1%, respectively). Regarding the retained sludge activity measurement, the nitrite oxidation rate was higher than the ammonium oxidation rate (0.031 and 0.022 gram of nitrogen per gram of volatile suspended solids per day, respectively). In the 300 days of operation, the amount of excess sludge production was negligible. Thus, no sludge treatment system is required. Introduction of the DHS system in developing countries is recommended because this system requires a relatively small area, and has low electricity consumption and operation costs.
Untitled Document
The City of San Diego in California is the state's most southerly conurbation, sited just a few miles from the Mexican city of Tijuana – so close that a trolley bus runs every ten minutes down to the busy border at San Ysidro. A sprawling, pleasant mix of ultra-modern medium-rise blocks, wide palm-lined boulevards and Spanish-style dwellings, San Diego is experiencing the same inexorable population pressures as most Californian cities.
One area that remains relatively undeveloped,...
ABSTRACT
Two types of media, natural compost and a commercial engineered media, were evaluated in terms of sulfur toxicity and capacity for removal of hydrogen sulfide. A humidified gas stream of 50 ppmv H2S was passed through the media columns and effluent readings for H2S at the outlet were measured continuously. Sulfate was artificially added (40, 65, 100mg-S/g-compost) to the media to test its effect on removal efficiency and the biofilm and media. The overall baseline removal efficiencies of the natural...
Up to now, the recovery of precious metals used as catalysts in chemical processes has involved the use of incineration. Now, however, a British-Swedish joint venture has developed a process which uses supercritical water oxidation instead, which provides many economic and environmental advantages.
Precious metals are used extensively in catalysts in a wide range of industrial chemical processes. Sometimes they are used in a homogeneous form, but more often fixed to a solid support for ease of handling. In many...
The Kemwater Recycling Process – KREPRO for treatment of sewage sludge is based on a completely new separation technology, which uses existing knowledge in an innovative way. It reduces both the organic and inorganic content of the sludge. The organic content is re-duced by about 30% and the inorganic about 70% if digested sludge is treated. All metals and salts are dissolved; the remaining undissolved inorganics are mainly silicates like sand and grit.
In constast, most sludge treatment technologies used today...
Dairy wastewaters are rich in organic carbon and nutrients. When disposed without proper treatment they cause severe pollution of water and land. But if treated by anaerobic fermentation such wastewaters can yield useful clean energy in the form of methane. The systems commonly used for such fermentation throughout the world are Continuously Stirred Tank Reactors (CSTRs). We describe attempts to upgrade CSTR performance by incorporating biofilm support systems (BSSs) within the existing reactors. The focus of the...
Abstract
Waste represents an enormous loss of resources both in the form of materials and energy. Indeed, quantities of waste can be seen as an indicator of the material efficiency of society. Waste generation is increasing in the European Union, and amounted to about 3.5 tonnes of solid waste per person in 1995 (excluding agricultural waste) 1
Excessive quantities of waste result from:
inefficient production processes low durability of goods unsustainable consumption patterns. Solid waste is also increasingly...
`The oceans are in trouble and so are we,` oceanographer Sylvia Earle, National Geographic explorer in residence and researcher for the Smithsonian, was quoted as saying in an article on the web by Seth Borenstein writing for the Philadelphia Inquirer and San Jose Mercury News Washington Bureaus. Citing a study by the Harvard Medical School`s Center for Health and the Global Environment covering 1976 to 1996, Borenstein reports a greater than fourfold increase in harmful algal blooms (74 to 329). `stranding of...
Within the last decade, implementation of state and federal regulations and other local codes have changed biosolids processing in Florida. Previously, biosolids stabilization varied greatly among the state’s 3,500 to 4,000 wastewater treatment facilities. Public and privately owned wastewater treatment facilities were required to stabilize their biosolids to a minimum Class C standard for land application, with most facilities using aerobic or anaerobic digestion. Requirements for septage solids stabilization,...
The treatment of industrial effluent from the paper manufacturing facilities in British Columbia is a major concern because the effluent is discharged into prime salmon habitat in the marine environment (Cross, 1994). High levels of biological oxygen demand (BOD) in the effluent reduce the dissolved oxygen (DO) available to species in the marine environment. In 1988, the Federal Department of Fisheries and Oceans reviewed the levels of DO and total suspended solids (TSS) that are discharged in the effluent...
The use of compost in various environmental applications is one of the most intensive areas of compost research being pursued today. The high organic matter content and biological activity of compost makes it effective for use in a variety of applications. Five of these will be reviewed in this article: erosion control, revegetation, biofiltration, bioremediation, and wetlands construction.
EROSION CONTROL
Erosion control is a relatively new and promising application for compost. Research has shown that...
` In order to determine the impacts of a particular discharge on ambient water quality, it is usually necessary to model the diffusion and dispersion of the discharge in the relevant water body. The approach applies both to new discharges and to upgrading of existing sources. This note provides guidance on models that may be applicable in the context of typical Bank projects.`
Introduction
Mathematical models can be used to predict changes in ambient water quality due to changes in discharges of wastewater. In...
Pressures on the environment may occur through chemical, physical and biological agents. The subject of this study is physical agents, where physical fields are examined.
Physical fields are part of the natural environment. Depending upon their properties and the surrounding conditions, physical fields are transmitted through the spaces in which we live, potentially affecting human health and nature. Human activity can add to, modify, and enhance and reduce the intensity of these fields. Furthermore, changes in...
Customer comments
No comments were found for Development of a down-flow hanging sponge reactor for the treatment of low strength sewage. Be the first to comment!
