Advanced water treatment facilities are used widely, mainly to remove taste and odor and to reduce trihalomethane generation. Each such facility consists of an ozonation and biological activated carbon (BAC) process and has made the achievement in wateworks (Sato, 2002). To make these facilities more efficient, a large number of researchers were taken to make the ozonizer more efficient and to enhance treatment technology. The ozonizer was reduced in the discharge gap using oxygen, and thus increasing ozone concentrations to 300 g/Nm3. However, to avoid incomplete combustion and ensure safety, ozone concentrations must be within 150 g/Nm3 (Ishioka, 2002; Mizutani et al.,1999). The present report also demonstrates that ozonation technology is effective in removing taste and odor and in reducing trihalomethane ( Morioka et al., 1993; Morioka, 2001); and that bromate information can be suppressed by keeping concentrations of dissolved ozone to no more than 0.1 mg/L ( Kato et al 2002). To spread and establish ozonation more widely, basic research with demonstrative plants must be conducted with regard to ozonation techniques that are capable of handling raw water from waterworks.
In this study, the method of using high concentrated oxygen water to depurate the bottom sediment was confirmed to be effective. The high concentrated oxygen dissolver was developed and the lab scale experiment was performed. High rate, high efficiency oxygen dissolver was developed, the optimum running condition of the equipment and the method of making high concentrated oxygen water was discussed in this study. In addition, the inhibition of phosphorus release was also studied. On the basis of the fundamental knowledge from the lab scale study, pilot scale apparatus was set up and the pilot study was carried out.
In order to promote the application of constructed wetland technology for wastewater treatment and for preventing the Lake Dianchi Valley of China from further eutrophication, field studies was carried out, which included the small-scale, pilot-scale experiments, and finally demonstration treatment systems. In this study, the performance of a combined free water, subsurface constructed wetlands and ecological pond system was designed and adopted to treat one village's sewage. The monitor results of 430 days showed that the mean removal rates of total nitrogen, ammonia-nitrogen, total phosphorus and COD were 89.9%, 85.1%, 85.1% and 80.6%, respectively. The water quality could achieve the design requirement. The performance of wetland system in the storm was also investigated. The system could resist the impulse load of stormwater and had a good capacity to reduce the non-point source pollutants brought by the stormwater runoff.
Biological solubilization and mineralization process was proposed for food wastes. In the process food wastes are mixed with rice hull as biological support medium under wet condition and are solubilized or mineralized. The purposes of the study are to operate the biological solubilization and mineralization process without accumulation of food wastes and to increase mineralization rate for the reduction of organic loading to the sewerage system. Biological solubilization and mineralization process was operated without the accumulation of food waste by aeration in the circulation tank. The process can reduce organic loading to the sewage system to half by aeration in the circulation tank and 80 % by installing biofilm into the circulation tank. The process combined with biofilter would not require further treatment of effluent.
Wastewater biofilms are very complex multispecies biofilms, displaying considerable heterogeneity with respect to both the microorganisms present and their physicochemical microenvironments. To understand the eco-physiology of individual microorganisms in the biofilm, techniques and tools with a high spatial and temporal resolution are required for direct detection of the spatial distributions of microbial species and their activities in minimally disturbed their natural habitats (e.g., biofilms). In this paper, we will, therefore, address the great potential of the combined use of the current FISH technique and microelectrodes to study the microbial ecology of complex microbial communities such as biofilms. The combination of these two techniques will provide reliable and direct information about relationships between in situ microbial activity and the occurrence of specific microorganisms in biofilms. As an example of the combined study, we will illustrate the in situ spatial organization of ammonia-oxidizing and nitrite-oxidizing bacteria on fine scale in autotrophic nitrifying biofilms by applying the full-cycle of 16S rRNA approach followed by fluorescence in situ hybridization (FISH), which is linked to their in situ activity distributions at a similar resolution determined by use of microelectrodes. The combination of these techniques allows relating in situ microbial activity directly to occurrence of nitrifying bacteria population.
To estimate the long-term effects of ecosystem-manipulating lake restoration methods such as biomanipulation, we need a numerical model which can predict the succession of plankton community with sufficient accuracy. An accurate numerical model can be prepared based on an accurate data background. In this sense, two series of mesocosm (outdoor open-air pond) experiments that mimicked conditions in shallow and eutrophic water ecosystem were performed to clarify the effects of the zooplankton community on phytoplankton succession quantitatively. The experiments were carried out in both summer and winter periods. The results revealed that three types of zooplankton, namely rotifers, copepods, and cladocerans, have different effects on phytoplankton succession. Rotifers did not graze blue-green algae. Cladocerans suppress the growth of phytoplankton even for some blue-green algae effectively by their predation. The results of these experiments suggest that the amount of crustaceans, i.e., copepods and cladocerans, should be increased for the successful enforcement of biomanipulation. A model based on these quantitative outcomes, and its prediction of a biomanipulation for an eutrophic shallow lake is also mentioned.
The function of clams on the decomposition and biodegradability improvement of organic matters in tidal flat sediment were investigated. Moreover, nitrate removal capacity of tidal flat sediments with and without clams was also evaluated. It was found that concentration of DOC in tidal flat sediment with clams was about 1.1-2.1 mg/l higher than that in the sediment without clams. Also NH4-N concentration in the sediment with clams was 0.8-1.8 mg/l higher than that in the sediment without clams. DOC from the sediment with clams was readily biodegradable, while DOC in the sediment without clams was inherent biodegradable substance. Molecular weight of organic matters was distributed from 0.7x102 to 1.7x105 and 0.7x102 to 1.2x106 in the pore water of the sediment with and without clams, respectively. This indicated that clams accelerated the degradation of particulate organic matters and produced DOC, NH4-N and others compounds with higher biodegradability and lower molecular weight. The increase of readily biodegradable compounds as carbon and nutrients sources enhanced microbial growth and accelerated nitrate removal process in tidal flat sediment with clams.
A concept of Modeling WWTP (wastewater treatment plants) and a case study in Qinghe WWTP were described in the paper. The new concept of Modeling WWTP is to put each element, which composes the whole WWTP, including wastewater treatment process or units, constructions, controllers and sensors, etc., into a whole modeling system. That is, a virtual WWTP in a computer system will be set up, with the mathematic models to describe every component in the WWTP and some computer language such as C#.NET and Visual Basic, to achieve the functions of data transfer, analysis and simulation of the whole process. The ultima objective is to apply appropriate WWTP software and monitor systems to the wastewater treatment process, and to achieve process simulation and management, so as to afford more efficient and more stable control and management on WWTP. A successful Modeling WWTP includes a careful selection of mathematical model and simulation software, a dissective analysis of interaction and conversion between practical operation data and model parameters, a sufficient collocation of many kinds of online/inline/offline apparatuses which can afford the operation data, and a systemic construction of communication services which can collect and transfer the data from apparatuses, monitoring systems and simulation software. The paper illustrated the detailed approaches to establish a Modeling WWTP with a case study in Qinghe WWTP in Beijing, China.