Comprehensive temperature monitoring in an in-vessel forced-aeration static-bed composting process

Comprehensive temperature monitoring was done in an in-vessel forced-aeration static-bed composting process using sewage sludge. The three layers that divided the compost pile horizontally showed different temperature distributions. The temperature of the top layer appeared not to be influenced by the ambient temperature. The temperature of the center area of the top layer was taken to be the representative temperature for evaluating composting start-up performance. The temperature of the bottom layer was strongly influenced by the ambient temperature, and the temperature of the center area of the bottom layer was taken to be the representative temperature for pathogen control as it was the minimum temperature in the reactor. Composting start-up performance was influenced by several factors when the ambient temperature was either below or above 20°C. When the ambient temperature was below 20°C, the time taken to reach 65°C (T ₆₅) was influenced by the temperature of inflowing air, but when the temperature was higher than 20°C, it was influenced by the ratio of sewage sludge to seed compost (F/S). T ₆₅ was least when F/S was 1–2. Received: January 9, 2001 / Accepted: October 10, 2001     

Sorption of biodegradation end products of nonylphenol polyethoxylates onto activated sludge

IntroductionRecently ,nonylphenolpolyethoxylates (NPnEO (n :numberofethoxyunits(EOs) )havebecomeaproblematicissueforthereasonthatthesecompounds,animportantgroupofnonionicsurfactants ,havebeenusedwidelyinvariousindustriesasflocculants,dispersants,emulsifie…     

Comparative mammalian cell cytotoxicity of wastewater with elevated bromide and iodide after chlorination, chloramination, or ozonation

Recycling wastewater is becoming more common as communities around the world try to better control their water resources against an increased frequency of either prolonged droughts or intense flooding. For communities in coastal areas, wastewaters may contain elevated levels of bromide(Br~-) and iodide(I~-) from seawater intrusion or high mineral content of source waters. Disinfection of such wastewater is mandatory to prevent the spread of pathogens, however little is known about the toxicity of wastewater after disinfection in the presence of Br~-and I~-. In this study we compared the induction of chronic cytotoxicity in mammalian cells in samples of municipal secondary wastewater effluent amended with elevated levels of Br~-/I~-after disinfection by chlorine, chloramines or ozone to identify which disinfection process generated wastewater with the lowest level of adverse biological response. Chlorination increased mammalian cell cytotoxicity by 5times as compared to non-disinfected controls. Chloramination produced disinfected wastewater that expressed 6.3 times more cytotoxicity than the non-disinfected controls and was 1.3 times more cytotoxic than the chlorinated samples. Ozonation produced wastewater with cytotoxicity comparable to the non-disinfected controls and was at least 4times less cytotoxic than the chlorine disinfected wastewaters. These results indicate that compared to chlorination and chloramination, ozonation of wastewater with high Br~-/Ilevels yielded the lowest mammalian cell cytotoxicity, suggesting its potential as a more favorable method to disinfect wastewater with minimizing the biological toxicity in mind.     

Sustainable livelihoods development by utilization of geomorphological resources in the Bai Tu Long Bay,Quang Ninh Province,Vietnam

Located in the humid tropical zone and endowed with carbonate sedimentary formations, Vietnam has unique karst landscapes where caves, limestone, and dolines are common. If well managed, these are valuable geomorphological resources for a sustainable socio-economic development. Although publications on sustainable livelihoods associated with conserving biodiversity and local culture are plentiful, there is still a lack of studies linking livelihood quality with the conservation of geomorphological resources, in particular in karst areas. This study assesses the geomorphological resources in Vietnam’s Bai Tu Long Bay and studies the relationship between livelihood and these resources. The current research area Bai Tu Long Bay is adjacent to the natural World Heritage site of Ha Long Bay in the Vietnamese part of the Gulf of Tonkin. Bai Tu Long is characterized by a karst landscape, which is at the same time similar but also different from Ha Long Bay. A field survey and interviews with 153 households allowed assessing people’s perception of the value of the geomorphological resources and their importance for local income. The results show that Bai Tu Long Bay has abundant, diverse, and unique geomorphological resources, which are valuable for tourism development. However, the local people are unaware of these values likely because they have no direct benefit from them. Further a sustainable development strategy for Bai Tu Long Bay is recommended. The outcome is a proposal for tourism initiatives aiming at realizing more sustainability in the area.     

Primary biosorption mechanism of lead (II) and cadmium (II) cations from aqueous solution by pomelo (Citrus maxima) fruit peels

Environmental Science and Pollution Research - The present work investigates the primary adsorption mechanisms of lead (II) and cadmium (II) cations onto pomelo fruit peel (PFP) from aqueous...     

Spatial and temporal variations of PAHs in surface sediments of estuarine and coast of CanGio wetland,Vietnam

Surface sediments from estuarine and coast of CanGio wetland (CGW) of Hochiminh City, Vietnam, were investigated to identify the spatial and temporal variations of polycyclic aromatic hydrocarbons (PAHs). The total PAHs showed wide variation but similar to patterns observed (F?=?0.901, p?=?0.46) in LongTau (31?±?77 ng/g dry weight, n?=?13), SoaiRap (53?±?81, n?=?4), ThiVai (60?±?62, n?=?10) estuaries, and coastal areas (112?±?211, n?=?9). A decreasing trend in the wet season (F?=?8.8, p?=?0.01) reflected that inland sources such as wastewater discharged and atmospherically transported contaminants contributed to PAHs in sediments. The risk posed by the PAHs in the coastal and estuarine areas of CGW is still negligible. The present study provides baseline data, which can be used for regular monitoring and future strategy of environmental protection for the study area.

     

Transboundary hazardous waste management. Part I: Waste management policy of importing countries.

Mixed metal-containing waste, polychlorinated biphenyls (PCB) containing capacitors, printed circuit boards, steel mill dust and metal sludge were among the most common wastes exported from Taiwan. Before the implementation of the self-monitoring model programme of the Basel Convention (secretariat of the Basel Convention 2001) in the Asia region, Taiwan conducted a comprehensive 4-year follow-up project involving government authorities and the waste disposal facilities of the importing countries. A total of five countries and nine plants were visited in 2001-2002. The following outcomes can be drawn from these investigations. The Chinese government adopts the strategies of 'on-site processing' and 'relative centralization' on the waste management by tightening permitting and increasing site inspection. A three-level reviewing system is adopted for the import application. The United States have not signed the Basel Convention yet; the procedures of hazardous waste import rely on bilateral agreements. Importers are not required to provide official notification from the waste exporting countries. The operation, administration, monitoring and licensing of waste treatment plants are governed by the state environmental bureau. Finland, France and Belgium are members of the European Union. The procedures and policies of waste import are similar. All of the documents associated with transboundary movement require the approval of each government involved. Practically, the notification forms and tracking forms effectively manage the waste movement.     

Optimization, equilibrium, adsorption behavior and role of surface functional groups on graphene oxide-based nanocomposite towards diclofenac drug

Aquatic contamination of diclofenac (DCF), an emergent non-steroidal anti-inflammatory drug (NSAIDs), can result in adverse effects to many ecosystems through biomagnification. Hence, introducing effective remediation techniques to sequester the pharmaceutical wastes is highly fundamental to prevent their accumulation in the environment. Generally, adsorption has been presented as a green and efficient approach. Herein, we report the characterization and application of the novel magnetic nanocomposite ([email protected]₂O₄) derived from cobalt-based ferrite (CoFe₂O₄) and graphene oxide (GO) for DCF adsorption. For the optimization procedure, the response surface methodology (RSM) was adopted to investigate the impacts of DCF concentration (1.6–18.4 mg/L), DCF dosage (0.08–0.92 g/L), and solution pH (2.6–9.4) to find the optimum conditions for DCF removal, at 10.5 mg/L, 0.74 g/L, and pH 4, respectively. For the adsorption experiments, the kinetic, isotherm, thermodynamic, and intraparticle diffusion models were systematically studied. Moreover, we have elucidated the role of functional groups on the surface of [email protected]₂O₄ in enhancing the adsorption of DCF drug. With good removal efficiency (up to 86.1%), high maximum adsorption capacity (32.4 mg/g), [email protected]₂O₄ can be a potential candidate to eliminate DCF drug from water.     

Organotin contamination in fishes with different living patterns and its implications for human health risk in Taiwan

Contaminated levels of butyl- and phenyltin compounds, tributyltin (TBT), dibutyltin (DBT), monobutyltin (MBT), triphenyltin (TPT), diphenlytin (DPT), and monophenyltin (MPT), were investigated in pelagic, demersal and cultured fish species from different seasons and locations in Taiwan. Seasonal variations were found in fishes from Wuchi and Hsingta fishing harbors for their butyltin levels (winter>summer) with the opposite trend for phenyltins in fishes from Patoutzu fishing harbor and demersal fishes from four fishing harbors (summer>winter). Fish liver contained the lowest percentage of TBT and the highest percentage of TPT among six organotin compounds. Consumption of contaminated pelagic species and fishes from Hsingta fishing harbor had the highest hazard index. However, the hazard quotients and hazard indices were all less than 1, suggesting a daily exposure at these levels of TBT, DBT and TPT may not be likely to cause any deleterious effects during lifetime in human population.