Investigation of microplastic contamination in blood cockles and green mussels from selected aquaculture farms and markets in Thailand.

Recent studies have indicated that bivalves are bioindicators for microplastic pollution since they are filter feeders and accumulate microplastics (MPs) during their feeding process. This study focused on the investigation of MPs in blood cockles (Tegillarca granosa) and green mussels (Perna viridis) from selected aquaculture farms and markets in Thailand. The abundance of MPs was identified by fluorescence microscopy with Nile Red tagging and the polymer detection by micro-Fourier Transform Infrared Spectroscopy (micro-FTIR). The number of MPs in blood cockle samples from the Khlong Dan market and the BangBo aquaculture farm was 11 ± 5 and 6 ± 1 particles/individual, respectively. For green mussel samples, the number of MPs from the Talaad Thai market and the Sriracha fisheries research station was 96 ± 19 and 11 ± 7 particles/individual, respectively. The results of the study indicate that the number of MPs in bivalve samples from the markets is much higher than in the aquaculture farms. This probably is due to the contamination of MPs in bivalves during the packaging and transportation processes. However, further studies are needed to confirm this. The predominant MPs were fragments and fibres with a size range of 0.05-0.3 mm. Most polymers were polypropylene, polyethylene, copolymer, polyester, and nylon. In brief, this study showed the contamination of MPs in bivalves cultivated for human consumption. The accumulation of MPs in these marine bivalves can lead to the biomagnification of MPs along the food chain. This can impact food safety and human health.

Boron removal and its concentration in aqueous solution through progressive freeze concentration.

This study explored the feasibility of progressive freeze concentration in boron removal and its concentration in aqueous solution. The influence of three key parameters in progressive freeze concentration on boron removal and concentration, namely, the advance speed of the ice front, the circumferential velocity of the stirrer, and the initial boron concentration, are investigated by conducting batch experiments. The results show that the effectiveness of boron removal increases with a lower advance speed of the ice front, a higher circumferential velocity of the stirrer, and a lower initial boron concentration. For a model boron solution with an initial concentration of 100 mg/L, the boron concentration in the ice phase after progressive freeze concentration is below 1 mg/L when the advance speed of the ice front is lower than 1 cm/h and the circumferential velocity of the stirrer is higher than 0.12 m/s. In addition, the concentration of boron in the liquid phase occurs simultaneously with progressive freeze concentration. Furthermore, the results also suggest that this method can be applied to the purification and concentration of not only organic molecules but also inorganic ions.

Rapid reduction of lead leachate from hazardous fly ash using microwave treatment with acid combination.

The novelty of this study is to rapidly reduce hazardous lead leachates from solid waste using microwave digestion treatment, which is an energy-saving and low greenhouse gas emission technology. The article presents the reduction of toxic characteristic leaching procedure-extractable lead concentration in the municipal solid waste incineration fly ash by the microwave digestion treatment in HNO3/H2SO4 combination, and focuses on the effects of treatment time and temperature. The results obtained from this study indicated a significant reduction efficiency of toxic characteristic leaching procedure-extractable lead concentration and showed sufficient reduction in leaching levels to render the treated fly ash safe in lead compound leaching characteristics. The reduction efficiency of toxic characteristic leaching procedure-extractable lead concentration can reach 98% in 15 minutes of treatment time. This is equivalent to the original toxic characteristic leaching procedure-extractable lead concentration of 46.2 mg L(-1) in raw fly ash being reduced down to less than 1.0 mg L(-1). Based on the experimental data obtained in this study, a useful correlation between reduction efficiency and treatment conditions is proposed. For engineering applications, the necessary minimum treatment time is solved using a graphic illustration method, by which the minimum treatment time (t(min)) is obtained if the desired reduction efficiency (η) and treatment temperature (T) are known. The effects of treatment time and temperature are discussed. Some problems caused by the microwave digestion treatment method are also delineated in this article.

Two-step accelerated mineral carbonation and decomposition analysis for the reduction of CO2 emission in the eco-industrial parks.

Carbon dioxide (CO2) emissions are a leading contributor to the negative effects of global warming. Globally, research has focused on effective means of reducing and mitigating CO2 emissions. In this study, we examined the efficacy of eco-industrial parks (EIPs) and accelerated mineral carbonation techniques in reducing CO2 emissions in South Korea. First, we used Logarithmic Mean Divisia Index (LMDI) analysis to determine the trends in carbon production and mitigation at the existing EIPs. We found that, although CO2 was generated as byproducts and wastes of production at these EIPs, improved energy intensity effects occurred at all EIPs, and we strongly believe that EIPs are a strong alternative to traditional industrial complexes for reducing net carbon emissions. We also examined the optimal conditions for using accelerated mineral carbonation to dispose of hazardous fly ash produced through the incineration of municipal solid wastes at these EIPs. We determined that this technique most efficiently sequestered CO2 when micro-bubbling, low flow rate inlet gas, and ammonia additives were employed.

Evaluation of the flocculation and de-flocculation performance and mechanism of polymer flocculants.

Understanding the interaction mechanism between polymeric flocculants and solid particles in two oppositely charged solutions: bentonite and calcium fluoride, is of great practical and fundamental importance. In this work, inorganic flocculants based on aluminum(III) or iron(III); cationic, anionic and non-ionic organic flocculants were used. The solution pH, which highly influenced the flocculation performance of the system, has been used as a function of turbidity removal, sediment volume and velocity. Results show that the flocculation of inorganic polymers does not depend on the zeta potential but on the solution pH, contrary for cationic and anionic polymers. Non-ionic polymer was independent on both. By varying the final pH of the heterogeneous solution formed of flocs-liquid, it was found for inorganic polymers, the optimum condition of pH < 3 to separate inorganic flocculant particles from flocs. Inductively coupled plasma atomic emission spectrometer and X-ray fluorescence analysis proved the reversibility of flocculation process by indicating the concentration of flocculant representative atom (Al or Fe) in the flocs and in the emerging solutions when the flocculation was optimized and the reversibility was effective. As results, weak forces were suggested as responsible for inorganic polymers flocculation where electrostatic interaction and hydrogen bonds may enroll the mechanism of organic flocculants.

Nano to micro particle size distribution measurement in the fluid by interactive force apparatus for fine particle processing.

The direct measurement of fine particles size distribution of dispersions or coagulations in liquid is important for water purification, fine particles separation for recycling and mineral processing, as well as the new material production. The nano to micro particle size is usually measured by light scattering method; however, it is difficult to measure at high concentration of suspension. Here, a novel dynamical method by using the interactive force measurement between particles in liquid under electric field is used for measuring distribution of fine particle. Three types of nano to submicron particles, that is well-dispersed nano particles, coagulated nano particles and settled submicron particles, have been measured by interactive force measurement method. The particle size distributions are compered with the size distributions of dried particles measured by TEM or SEM. The well-dispersed nano particle size distribution by interactive force measurement is influenced by the nano size surfactant micelles. The size distribution of coagulated nano particles in water is larger than the result by TEM. On the other hand, the submicron nickel particle size distribution is similar with the one analyzed by SEM.

Leaching of indium from obsolete liquid crystal displays: comparing grinding with electrical disintegration in context of LCA.

In order to develop an effective recycling system for obsolete Liquid Crystal Displays (LCDs), which would enable both the leaching of indium (In) and the recovery of a pure glass fraction for recycling, an effective liberation or size-reduction method would be an important pre-treatment step. Therefore, in this study, two different types of liberation methods: (1) conventional grinding, and (2) electrical disintegration have been tested and evaluated in the context of Life Cycle Assessment (LCA). In other words, the above-mentioned methods were compared in order to find out the one that ensures the highest leaching capacity for indium, as well as the lowest environmental burden. One of the main findings of this study was that the electrical disintegration was the most effective liberation method, since it fully liberated the indium containing-layer, ensuring a leaching capacity of 968.5mg-In/kg-LCD. In turn, the estimate for the environmental burden was approximately five times smaller when compared with the conventional grinding.