The high moisture content (80%) in the sewage dewatered sludge is the main obstacle to disposal and recycling. A chemical
dewatering and stabilization/solidification (S/S) alternative for the sludge was developed, using calcined aluminum salts (AS) as
solidifier, and CaCl2, Na2SO4 and CaSO4 as accelerators, to enhance the mechanical compressibility making the landfill operation
possible. The properties of the resultant matrixes were determined in terms of moisture contents, unconfined compressive strength,
products of hydration, and toxicity characteristics. The results showed that AS exhibited a moderate pozzolanic activity, and the mortar
AS0 obtained with 5% AS and 10% CaSO4 of AS by weight presented a moisture contents below 50%–60% and a compressive strength
of (51.32 ± 2.9) kPa after 5–7 days of curing time, meeting the minimum requirement for sanitary landfill. The use of CaSO4 obviously
improved the S/S performance, causing higher strength level. X-ray diffraction, scanning electron microscopy and thermogravimetrydifferential
scanning calorimetry investigations revealed that a large amount of hydrates (viz., gismondine and CaCO3) were present in
solidified sludge, leading to the depletion of evaporable water and the enhancement of the strength. In addition, the toxicity characteristic
leaching procedure (TCLP) and horizontal vibration (HJ 557-2009) leaching test were conducted to evaluate their environmental
compatibility. It was found that the solidified products conformed to the toxicity characteristic criteria in China and could be safely
disposed of in a sanitary landfill. 相似文献
The levels and distributions of polybrominated diphenyl ethers (PBDEs) in chicken tissues from an electronic waste (e-waste)
recycling area in southeast China were investigated. Human dietary intake by local residents via chicken muscle and eggs was estimated.
The mean PBDEs concentrations in tissues ranged from 15.2 to 3138.1 ng/g lipid weight (lw) and in egg the concentration was 563.5
ng/g lw. The results showed that the level of total PBDEs (PPBDEs) in the chicken tissue was 2–3 orders of magnitude higher than
those reported in the literature. The large di erence of PPBDEs concentrations between tissues confirmed that the distribution of
PBDEs in tissues depend on tissue-specificity rather than the “lipid-compartment”. BDE-209 was the predominant congener (82.5%–
94.7% of PPBDEs) in all chicken tissues except in brain (34.7% of PPBDEs), which indicated that deca-BDE (the major commercial
PBDE formulation comprising 65%–70% of total production) was major pollution source in this area and could be bioaccumulated in
terrestrial animals. The dietary PBDEs intake of the local residents from chicken muscle and egg, assuming only local bred chickens
and eggs were consumed, ranged from 2.2 to 22.5 ng/(day kg body weight (bw)) with a mean value of 13.5 ng/(day kg bw), which was
one order of magnitude higher than the value reported in previous studies for consumption of all foodstu s. 相似文献
A kinetic model for the Ti(IV)-catalyzed H2O2/O3 process was established, and the experimental results demonstrated that the model could well describe this ozone-based oxidative system mathematically and chemically. 相似文献
Polybrominated diphenyl ethers (PBDEs) are a class of organic pollutants. They are used as flame retardants that caused worldwide environmental concern. This study investigated the occurrence of PBDEs in soils and dusts from three plastic manufacture plants and surrounding areas in Eastern China. A total of 13 PBDE congeners were detected using gas chromatography-mass spectrometer (electron impact ionization). The total concentrations of PBDEs range from 2.21 to 558, 19.7–4916, and 8.70–18,451 ng/g dry weight in the soils of three sampling areas, with mean of 1004 ng/g d w; in dusts, the concentrations range from 7240 to 10,469, 684–4482, and 193–3989 ng/g d w, with an overall mean of 3619 ng/g d w. The most abundant congener is the BDE-209, followed by BDE-153 and BDE-85. This indicates that the brominated flame retardant added in the plastic manufacture is mainly the commodity decabromodiphenyl ether. In comparison with other polluted areas around the world, the PBDE concentrations in the soils of the plastic manufacture plants are similar to those in soils of waste plastic disposal areas and PBDEs production sites, but orders of magnitude higher than those in agricultural soils, mountain soils and rural soils. Daily exposure was estimated using the average concentrations of the pollution sites. The hazard quotient shows that the PBDEs pose considerable human health risks, especially to children, to which attention should be paid.