Foreword

The animal waste and agro-wastewater related problems become an important issue for environmental scientists in recent days. Nitrogen overload in cropland due to increased agricultural activity as well as an excessive use of fertilizer was an example of the agro-related pollution problem. Recently, Korea had encountered a very serious animal waste problem that caused deterioration of water quality in receiving water bodies. Realizing that the animal waste was the major source of water quality problem, Korean government established a new effluent standard including nutrient removal for animal waste treatment plants. The effluent nitrogen limit was 60mgL . However, most of the Korean engineers realized that the new standard was too tough to be attainable without an aid of advanced technologies. No animal waste treatment plants could achieve the required goal at that time. This situation had become a motive to host the specialty symposium on ‘‘Strong nitrogenous and agro wastewater’’ held in June 11–14, 2003 in Seoul, Korea. The scientific basis for nitrogen removal technologies with various biological and physico–chemical measures seems well established, but it requires more accumulated experiences for practical applications. For instance, the biological nitrogen removal technologies have been used for many years in municipalities, which dealt with a maximum nitrogen concentration of only 50mgL . However, the reject water from sludge treatment flow in municipal sewage treatment plants discharges as high as 1,500mgNL , while piggery waste and nightsoil generally exhibit much higher nitrogen concentrations of around 5,000mgL . These strong nitrogenous wastes are new challenge for nitrogen removal technology. In addition, means to improve the environment quality in agricultural area and how to remove refractory organics such as colors from the effluents in the industries dealing with textiles, paper products, tanneries, and other agro products would be the relevant scientific issues. Nitrogen is an essential nutrient not only for human health but also for all living organisms. The nitrogen input to our environment has tremendously increased during the last 40 years as shown in Fig. 1. The reason of the increased nitrogen input was primarily due to the expectation of increased crop yield, but there have