decolourisation of cotton bleaching effluent with wood rotting fungus

The decolourisation of cotton bleaching effluent by a wood rotting fungus was studied. It was found that fungus No. 7 could remove more than 70% of the colour (initial A₄₀₀=2.0–2.4) from the effluent within 4 days under agitated conditions. The fungal mycelia could be reused for a prolonged time and the decolourisation activity of mycelial pellets was quite stable during a long period of cool storage. Many factors affecting the decolourisation process were studied, including: concentration of glucose, effluent, NH₄⁺ and Mn(II); initial pH; temperature. The activity of manganese peroxidase (MnP) appeared to correlate well with the decolourisation rate. After the fungal treatment, an improvement in the treatability of the effluent by other microorganisms was observed.     

Pectinesterase extraction from Mexican lime (Citrus aurantifolia Swingle) and prickly pear (Opuntia ficus indica L.) peels

Extracts from Mexican lime (Citrus aurantifolia Swingle) and prickly pear (Opuntia ficus indica L.) peels were tested for their pectinesterase activity. A factorial design was applied in this study as a method for enzyme extraction in which the variables were the source of enzyme (prickly pear and Mexican lime peels) and the NaCl solution concentration (0–3.0 M). In all cases, enzyme extracts obtained using the same NaCl concentration from lime peel showed higher activity than extracts from prickly pear peel. NaCl concentration influenced the pectinesterase extraction process in both cases. Maximum enzyme activities were obtained with NaCl 0.5 M and 1.0 M for Mexican lime and prickly pear peels, respectively.     

Screening of selected flavonoids and phenolic acids in 19 berries

Selected flavonoids (kaempferol, quercetin, myricetin) and phenolic acids (p-coumaric, caffeic, ferulic, p-hydroxybenzoic, gallic and ellagic acids) were simultaneously detected from 19 berries using a simple High Performance Liquid Chromatographic (HPLC) method. These phenolics have been proposed to have beneficial effects on health as antioxidants and anticarcinogens. Marked differences were observed in the phenolic profiles among the berries, with certain similarities within families and genera. The major phenolic compound analyzed in the genus Vaccinium was quercetin in lingonberry and cranberry, and its level was high also in blueberries and bilberry. In the genus Ribes, quercetin was the main compound in gooseberry, red currant and black currant. Ellagic acid was the main phenolic compound in the berries of the genus Rubus (red raspberry, Arctic bramble and cloudberry) and genus Fragaria (strawberry). Our data suggest that berries have potential as good dietary sources of quercetin or ellagic acid.     

板栗内皮对酸性废水中重金属的吸附

选取板栗内皮作为吸附剂,在实验室条件下,通过振荡吸附的方法研究了板栗内皮对PH2．0的酸性废水中,镉、铅、铜、锌4种重金属离子的吸附特性。研究结果表明,当板栗内皮的加入量为30g／L,反应时间1h,达到对溶液中4种重金属离子的最大去除率,分别为Cd98．9％、Pb99．6％、Zn98．9％、Cu98．7％;热力学实验结果表明,板栗内皮对4种重金属离子的吸附容量分别为Cd3．2、Pb90．8、Zn27．3、Cu52．4mg／g;动力学实验结果表明,吸附反应在60min内可以达平衡。Elovich方程最适合描述板栗内皮吸附重金属离子的动力学行为,板栗内皮对镉、铅、铜、锌4种重金属的吸附速率和吸附时间成反比,同一时刻对4种重金属离子吸附速率大小依次是Pb2＋〉Cd2＋〉Cu2＋〉Zn2＋。     

Physicochemical and environmental properties of arsenic sulfide sludge from copper and lead−zinc smelter

Physicochemical properties of arsenic sulfide sludge (ASS) from copper smelter (ASS-I) and lead−zinc smelter (ASS-II) were examined by XRD, Raman spectroscopy, SEM−EDS, TG−DTA, XPS and chemical phase analysis method. The toxicity characteristic leaching procedure (TCLP), Chinese standard leaching tests (CSLT), three-stage sequential extraction procedure (BCR) and batch leaching experiments (BLE) were used to investigate the environmental stability. The ASSs from different smelters had obviously different physicochemical and environmental properties. The phase composition and micrograph analysis indicate that ASS-I mainly consists of super refined flocculent particles including amorphous arsenic sulfide adhered with amorphous sulfur and that ASS-II mainly consists of amorphous arsenic sulfide. The valence state of arsenic in both sludges is trivalent, but the valence composition of sulfur is quite different. The ASSs have thermal instability properties. The results of TCLP and CSLT indicate that the concentrations of As and Pd in the leaching solution exceed the standard limits. More than 5% and 90% of arsenic are in the form of acid soluble and oxidizable fractions, respectively, which explains the high arsenic leaching toxicity and environmental activity of ASS. This research provides comprehensive information for the disposal of ASS from copper and lead−zinc smelter.     

Efficient biased random bit generation for parallel lattice gas simulations

Lattice gas methods are often used to model the kinetics of a variety of diffusive systems. One of the main advantages of these methods is the ease at which they can be parallelized using simple bit vector operations. However, to describe the kinetics of the lattice gas in a randomly biased fashion, it is necessary to efficiently generate a randomly biased bit vector. If one generates a random floating point number per bit, then this is very costly. In this paper, an efficient algorithm is developed that leads to a fully bit vector implementation of a lattice gas automation while significantly reducing the amount of needed generated random floating point numbers. The bit vector algorithm using the new random biased bit vector algorithm is tested on a lattice gas method whose solution is modeled by the solution of the 1-D Burgers' equation. This new lattice gas method is then implemented on the BBN TC2200 and CRAY 90 parallel processors.     

The statistical power and biological information of two Daphnia juvenile production test designs

This paper examines the statistical power for two designs of Daphnia chronic toxicity test, one (the “old” OECD method) using four groups of 10 animals at each treatment, the other (the “new” OECD method) using 10 individually housed animals at each treatment. Both use reproduction as the end point. It was demonstrated during a pilot ring test of the new method, run concurrently with the old method, that their statistical powers were similar. The old method had a power for detecting a 20% real difference of 0.97, while the power of the new method was 0.90. These findings are reported, together with observations on the quality of data that may be obtained using the different test designs. It is suggested that the new design may be of use in investigating toxicological modes of action, in view of the improved data capture that it allows.     

The influence of the high and low molecular weight fractions of a bleach kraft mill effluent on the microbial activity of activated sludge

The high molecular weight (HMW) fraction (> 1000 Da) of bleached kraft mill effluent (BKME) is the principal source of adsorbable organic halide (AOX), colour and chemical oxygen demand in treated effluent. The influence of HMW material on the microbial activity of activated sludge microorganisms was studied in a series of batch growth experiments using fractionated effluent. The HMW material in the untreated effluent comprised 80% of the AOX but only 20% of the soluble COD. Multivalent metal ions had a greater affinity for this HMW fraction. The addition of HMW material to the LMW fraction had a stimulatory effect on microbial activity as measured by increases in biomass and substrate utilization. Chemical characterization and subsequent growth experiments revealed that nitrogen, which was deficient in the LMW effluent, was primarily associated with the HMW material. The association of nitrogen with the HMW fraction may have an important role on the behaviour of nitrogen within a biological treatment system and in the receiving environment.