Arsenic determination in soils and hair from schools in past mining activity areas in Ron Phibun district,Nakhon Si Thammarat province,Thailand and relationship between soil and hair arsenic

Arsenic (As) in soils and hair collected from schools in Ron Phibun district, Nakhon Si Thammarat province, Thailand, where former tin mining operation were located, was determined by hydride generation atomic absorption spectrophotometry. The relationship between As content in soils and hair with distance from secured landfill was also investigated. Soil and hair samples were collected from 6 schools in summer (February) and rainy season (July). For soils, silt+clay (<45 µm) fraction and sand (45 µm–2 mm) fraction were analyzed. The average concentrations of arsenic in soils during summer (21.70 ± 16.79 mg/kg) and rainy season (22.45 ± 14.17 mg/kg) were at the same concentration level. The average arsenic content in hair samples was 2.24 ± 0.05 mg/kg in rainy season which was higher than 1.05 ± 0.04 mg/kg in summer. It was found that arsenic contents in hair and soils are correlated with the distance from the secured landfill. Most importantly, a positive relationship between arsenic content in hair and soil was obtained for rainy season, which indicated that arsenic in soil corresponded to arsenic in hair. The cancer risk from soils ranged from 4.48 × 10^?7 to 2.06 × 10^?6 indicating low carcinogenic risk to school children.     

Development of an effective extraction process for coenzyme Q10 from Artemia

A method for extracting coenzyme Q₁₀ (CoQ₁₀) from Artemia was developed. 1 g of fresh Artemia was incubated with 75 % acetic acid at (30 ± 2)°C for 24 h, followed by three consecutive extractions with a mixture of 5 mL of hexane and 5 mL of ethanol, then analysis by a validated high-performance liquid chromatography with a diode-array detector. The calibration curve for CoQ₁₀ was linear in a range of 1–50 μg mL^?1. The limits of detection and quantification were 0.3 μg mL^?1 and 1.1 μg mL^?1, respectively. Mean recoveries were 94–100 % with a high precision of below 10 %. The method developed was found to be simple, efficient and the time required for releasing CoQ₁₀ from Artemia was short. The method provides not only low energy consumption but is also practical for industrial applications.     

Treatment of natural rubber latex serum waste by co-digestion with macroalgae, <Emphasis Type="Italic">Chaetomorpha</Emphasis> sp. and <Emphasis Type="Italic">Ulva intestinalis</Emphasis>, for sustainable production of biogas

Biogas production is proposed as an alternative approach to using natural rubber Hevea brasiliensis latex serum, a major waste product from the production of concentrated latex. To make the most efficient use of the reactor size, the addition of macroalgal biomass as a co-substrate to the fermentation system was investigated. The biogas yield of latex serum as a single substrate was (398 ± 14) L per kg of volatile solids added (VSA). For the co-digestion system, algae mixed with serum were investigated at wet mass ratios of Chaetomorpha sp. to Ulva intestinalis to serum at 3:0:1, 2:0:2, 1:0:3, 0:1:3, 0:2:2 and 0:3:1. Theco-digestion system with latex serum at 2 to 3 out of 4 parts produced the highest biogas yields within the range of 422–460 L kg^?1 of VSA. Other parameters such as carbon to nitrogen mass ratio, total solids content and initial pH value were investigated at the constant ratio of 1: 3 of Chaetomorpha sp. to latex serum, and the parameter settings of 15, 10.5 % and 7, respectively, were close to optimal, with an (888 ± 155) Lkg^?1 of VSA cumulative gas yield. The methane yield of the optimised system over 45 days was (197 ± 16) L kg^?1 of VSA and the reduction in COD was (40 ± 4) %. Latex serum, whether alone or co-digested with algae in biogas production, appears to be promising for the management of waste in concentrated latex production.