Masafumi Tateda

The degradability of biodegradable plastics in aerobic and anaerobic waste landfill model reactors

Degradabilities of four kinds of commercial biodegradable plastics (BPs), polyhydroxybutyrate and hydroxyvalerate (PHBV) plastic, polycaprolactone plastic (PCL), blend of starch and polyvinyl alcohol (SPVA) plastic and cellulose acetate (CA) plastic were investigated in waste landfill model reactors that were operated as anaerobically and aerobically. The application of forced aeration to the landfill reactor for supplying aerobic condition could potentially stimulate polymer-degrading microorganisms. However, the individual degradation behavior of BPs under the aerobic condition was completely different. PCL, a chemically synthesized BP, showed film breakage under the both conditions, which may have contributed to a reduction in the waste volume regardless of aerobic or anaerobic conditions. Effective degradation of PHBV plastic was observed in the aerobic condition, though insufficient degradation was observed in the anaerobic condition. But the aeration did not contribute much to accelerate the volume reduction of SPVA plastic and CA plastic. It could be said that the recalcitrant portions of the plastics such as polyvinyl alcohol in SPVA plastic and the highly substituted CA in CA plastic prevented the BP from degradation. These results indicated existence of the great variations in the degradability of BPs in aerobic and anaerobic waste landfills, and suggest that suitable technologies for managing the waste landfill must be combined with utilization of BPs in order to enhance the reduction of waste volume in landfill sites.

Short- and long-term sorption/desorption of polycyclic aromatic hydrocarbons onto artificial solids: effects of particle and pore sizes and organic matters

In order to elucidate the effect of nanopores and organic matters on sequestration of contaminants, short- and long-term sorption and desorption of naphthalene and pyrene in seven artificial solid-water systems were studied. Fast sorption occurred in every case; steady states were reached within 1-5h. Sorption constants varied drastically among the seven absorbents, ranging from 1.19 to 5.29 x 10(3) for naphthalene, and from 24.3 to 6.52 x 10(4) for pyrene. Slow sorption continued to take place in some cases, especially on absorbents containing humic matter. Desorption usually took place in two stages, fast and slow, on both unaged and aged absorbents. Irreversibility of desorption occurred for every absorbent except for silica particles modified with octadecyl silyl. Aging led to a reduction of fast desorption fraction due to entrapment of the chemicals into nanopores and partitioning of the chemicals into condensed areas of humic matters, and showed no effect on slow desorption and irreversibility of desorption. On the whole, entrapment into nanopores and partitioning into humic matters are considered to be important for sequestration of contaminants. Irreversibility of desorption is considered to be a more influencing factor than percentage of desorption for describing the extent of sequestration.

Loss of metallic elements associated with ash disposal and social impacts

Abstract Economic, environmental and health-related impacts are discussed concerning the loss of metallic elements associated with the disposal of ash. Municipal solid waste incineration ash (MSWA), thermal power station coal ash (PSA), and sludge incineration ash from wastewater treatment facilities (WTSA) were selected as representatives of ash, due to the large amounts of them commonly generated. In the process of treatment and disposal of waste material, recycling (recycling and recovery) has been recommended and a consensus on their performances has also recently evolved. However, waste treatment in Japan is not presently elaborate enough when the total social impact is considered because metallic element recovery from waste such as ash is not taken into account. The total amounts of metallic elements in the ash were estimated. It was found that recovery of metallic elements from ash by final stage recycling could have reached approximately 30%, 22% and 45% of the aluminium, lead and zinc, respectively, that were recycled by front stage recycling. The importance of the recognition of metallic element recovery from ash is pointed out in order to pursue a better recycling system, which would further reduce the impact on the environment and human beings.

Analysis of hydrocyclone behaviors in the separation of particulates from highway rainfall runoff

In this study, the separation behaviors of particles in highway rainfall runoff using a Ø7.5 cm hydrocyclone were examined. The volume fraction and the total suspended solids concentrations in the overflow and underflow from the hydrocyclone were analyzed. The results indicated that the overflow volume fraction increased with increasing operational pressure, but decreased with decreasing ratio of underflow outlet to inlet sizes (D(u)/D(i)), while the underflow volume fraction showed contrary behavior. The TSS concentration ratio between the overflow and inflow (TSS(over)/TSS(in)) decreased as a function of the operational pressure, while the corresponding ratio of underflow to inflow (TSS(under)/TSS(in)) increased. There was no visible difference in the TSS(over)/TSS(in) ratio with increasing D(u)/D(i) ratio but the TSS(under)/TSS(in) decreased sharply. The particle removal efficiency was affected mainly by the particle size. The hydrocyclone can work well using 1.6 m natural water head, and it is more space saving and more efficient in the separation of fine particles than the sedimentation method.

COMMENTARY: Identifying the Fundamental Key to Improving the Social Status of Waste Management Workers by Examining the History of Nursing

This study is an attempt to find the fundamental key to improving the social status of waste management workers by examining the history of nurses. A strong prejudice and discrimination against waste management workers still exist in Japanese society. The social status of nurses also used to be extremely low, but has improved drastically. Nursing has become a profession that many parents would like their daughters to choose as a career. The drastic improvement resulted from a change in the mindset toward “patients.” Similarly, the status of waste management workers can be improved if people start thinking of waste in terms of resources. Improvement in the social status of waste management workers could be one of the powerful driving forces for making waste management a more interesting profession and respected field.

Preliminary Study of Treatment of Spent Test Tubes Used for Blood Tests by Acidic Electrolyzed Water

Test tubes are widely used in medical facilities, for example, for collecting blood specimens of patients undergoing health checkups. Plastic-made and disposable tubes are increasingly replacing glass-made tubes, owing to the fact that they are convenient and hygienic. Because of the increase in the population of senior citizens in Japan and the increase in people’s interest in their health, the amount of used test tubes will be much higher in the future. In Japan, recycling of medical waste is not a common practice, but there has been some research on medical waste management (Kagawa et al., 2006; Tamiya, 2004, Yamaguchi et al., 2002). Recycling of medical waste is gaining increasing popularity abroad, and it continues to attract the attention of researchers (Kushida, 2000; Bohlmann et al., 2005; Lee et al., 2002; Bartholomew et al., 2002). Test tubes used for blood tests are mostly made from polyethylene terephthalate (PET). In 2005, the total domestic demand for PET resin was 544,500 tons (Editorial Office of Monthly the Waste, 2006). Materials made of PET can be sold at a high price in the market; consequently, recycling industries in Japan are finding it increasingly difficult to source used PET materials. China in particular has a high demand and pays a good price for PET materials: Japan exported 338,000 tons of PET to China in 2009 (The Council for PET Bottle Recycling, 2010). Incineration has been the main treatment method for PET tubes; however, social consensus against dioxins discourages incineration. Heating treatment followed by direct disposal is another option for treating the tubes, but this option is not reliable since complete inactivation of pathogens in the tubes by heating treatment is not guaranteed. Besides, the heating treatment has another problem. Unlike the incineration treatment, heating leaves blood in the tubes after the treatment. The blood that remains in the tubes drips from the tubes during direct disposal process, which has ethical non-acceptance and implications even though pathogens in the blood would be completely killed.

Pursuing Simple and Low-cost Operation for Sludge Reduction via a Self-Oxidized Reduction Process in a Field-Scale Sewage Treatment Plant

Aims: A self-oxidized sludge reduction process was installed in a municipal sewage treatment plant at full scale in order to verify the efficiency of the process. Study Design: A full-scale (100 m 3 ) self-oxidized sludge reduction tank was constructed in a municipal sewage treatment plant and was operated for collecting data. Place and Duration of Study: The sewage treatment plant was located in a city of Toyama Prefecture, Japan. The field test was conducted from FY 2011 to 2015. Methodology: By observing BOD, SS, and CODMN and controlling them to conform to industrial wastewater discharge standards, the cost reduction of waste sludge disposal resulting from sludge mass reduction via the self-oxidized process was evaluated. Original Research Article Sekifuji et al.; JSRR, 18(2): 1-8, 2018; Article no.JSRR.40146 2 Results: In this study, the operation cost for a local small government in charge of the plant was reduced by more than 50,000 USD per year. Conclusions: The self-oxidized method can be an alternative sludge reduction method.

Taste Evaluation of Rice Grown in Soil Treated with Commercial Silica and Recycled Rice Husk Silica

Aim: To evaluate the taste of rice grown in soil treated with rice husk silica in order to elucidate the potential use of rice husk silica as a fertilizer in terms of taste of rice. Study Design: Rice plants were grown in soil treated with rice husk silica and officially approved, commercial silica fertilizer. The taste of the rice plants was compared based on their quality evaluation value (QEV). Location and Duration of Study: The study was conducted in the city of Imizu where the Toyama Prefectural University is located. The period of study was from March 2015 to April 2016. Methodology: Paddy fields were divided based on the type and amount of silica applied. The rice plants were grown under different conditions. The growth of rice plants and silica sorption by rice plants were analyzed to obtain data on the physical state of the rice plants. Taste of rice was evaluated by the QEV based on four parameters, contents of protein, water, amylose, and fatty acid. Results: It was observed that the taste of rice grown in soil treated with rice husk silica was not different from that of the rice grown in soil treated with commercial silica fertilizer. Conclusions: Rice husk silica can be used as a silica fertilizer in terms of taste of rice.

RESEARCH ARTICLE: Preparation for Establishing Environmentally and Socially Friendly Business in the Biomass Town of Imizu City, Toyama, Japan: A Case Study of the Waste Vegetable Oil–Recycling Business

Waste vegetable oil (WVO) collection from residents and its use in producing biofuel, which has many applications (e.g., as fuel for vehicles), have generated tremendous interest in Japan. Trials in this regard are mainly conducted in the so-called Biomass Town projects proposed by local governments. A Biomass Town project is the concept of establishing a sustainable, recycling-oriented society for recovering biomass, which is a recoverable energy source. In this study, nationwide studies were conducted to investigate the methods used by local governments to collect WVO in Japan; further, other investigations were carried out through circulating questionnaires to determine the best way in which to collect WVO from residents in Imizu City. These investigations found that each local government had exerted considerable effort to establish a system for collecting WVO from its residents, within their cultural and social limitations. Imizu City concluded that emulsion oil was a more profitable choice than biodiesel fuel for business, and that the generation of emulsion oil should be 600, 400, or 300 liters per day for two, three, or four workdays per week, respectively, for a monthly revenue of more than 40,000 yen, under the condition that the emulsion ratio is 80% kerosene and 20% WVO. The answers obtained from questionnaires revealed some basic information for the installation of an WVO ideal collection system, in the opinion of the residents.

Sludge Floc Behavior in an Elongated Rectangular Settling Tank

The different sludge floc distributions along the rectangular secondary settling tank were confirmed experimentally. Along the settling tank, three different regions can be formed: the fast settling zone near the inlet, the compaction zone in the middle, and the slowly settling zone near the outlet. Further investigation of morphological change of sludge flocs also showed corresponding floc characteristics: the bigger size of particles in the front, the relatively smaller particles with high density in the middle, and the small loose flocs in the rear. These were determined by the hydraulics and floc construction. The preceding results can be used as a guide to design systems to collect loose sludge solids.