Effect of chlorination practice on soluble organics

As the practice of chlorination for the disinfection of waste effluents is apparently to be extended, this study was initiated to examine the possibility that chlorinated organics could be formed in the disinfection process. A group of pure compounds that had been demonstrated to be susceptible to chlorination were examined under conditions likely to apply under normal disinfection practice.From the results obtained, it appears only organics with ring structures and electron activating substituents, or amino groupings are capable of chlorination. The frequent presence of ammonia or amino groups means that chloramine formation with its asociated toxicity is likely. However, the presence of ammonia or amino groups will retard the reaction with other compounds making chlorination of these unlikely.     

新的钢化技术及检验方法

近期有几个因素影响到玻璃钢化领域,不仅钢化工艺本身是推动钢化工业的主要因素,其它因素比如钢化市场的参与者们正面临着日益上升的全球化的竞争;客户需要高质量的产品和安全装配规则,新发明的非破坏性检验方法正代替成本较高的老方法;市场上满足汽车及建筑工业要求的新产品;最后钢化设备制造商所生产的满足于新玻璃产品的热处理要求的新产品。对这些问题全面进行了讨论以便为今天的钢化技术提供一个完整的画面。同时也对使用新钢化技术使钢化工业有更辉煌的明天提出了一些建议。     

Determination of flexibility of beam-to-column connectors used in thin walled cold-formed steel pallet racking systems

This paper describes a new test to determine flexibility of beam-to-column connectors used in conventional pallet racking systems. In this study, two different ways were used to find the flexibility of a connector. The connector developed was tested using the conventional cantilever method [Bajoria, KM. Three dimensional progressive collapse of warehouse racking, PhD Thesis, University of Cambridge, UK 1986], and then also using a newly proposed double cantilever method. To verify the results obtained from both the tests, a full scale frame test was carried out. In the double cantilever test the connector is subjected to three types of forces namely moment, shear and the axial pull by the beams, thereby giving behavior close to practical usage of connectors. Non-linear finite element analysis of both the tests and also of the full scale test were carried out using ANSYS [ANSYS 7.0—User's Manual, ANSYS Inc., 2005] software. The results obtained from the double cantilever test were found to match well with the full scale frame test. The experimental results and the finite element results are compared in this paper.     

Aggregate and concrete microfracture

Thin sections cut from cast concrete cylinders have been examined in transmitted light to investigate the significance of coarse aggregate type in “primary” microfracturing. Concretes manufactured with crushed-rock aggregates and gravel aggregates were studied and, in every case, the dominant fracture type was a parting of the aggregate-matrix bond. Bond cracking was least severe with the marble aggregate where epitaxial calcite over-growth was indicated. The ability of bond cracks to maintain continuity by bridging surface irregularities, via mortar cracks, reduced the inhibiting influence of rough-surfaced aggregate on bond-crack development.     

Oscillations of Foundations Installed on the Ground and Cast-in-Place Piles Subject to Kinematic Effects

Results are presented for experimental investigations on the traffic-induced oscillations of two full-scale foundations of a metallic tunnel, one of which is installed directly on the ground, and the other on cast-in-place piles. The foundations are close to one another with respect to mass and the load applied to them. Differences are revealed between the parameters of the actual oscillations of these foundations and their computed values.     

Upgrading the Activated-Sludge Process for Total Nitrogen Removal in Hong Kong

In order to protect the sensitive waters in Tolo harbour (Hong Kong), Sha Tin and Tai Po sewage-treatment works were first designed to remove 70% of the nitrogen load from the sewage. Since then, due to continuing serious eutrophication problems in the harbour, both plants have been modified to increase the removal efficiency to 90%.
The modifications were based on the Bardenpho process. However, the designers of the two plants adopted different approaches to process intensity, complexity and control of bacterial foam. At Sha Tin, the average monthly results have shown an increase of total nitrogen removal from 60–70% to about 80% since its completion. The addition of methanol was found to be ineffective on further enhancement of the denitrification rate due to difficulties in the apportioning of the second anoxic zone. The overall monthly results for Tai Po have also shown an increase in the removal rate to about 80%, even though 90% was achieved for a short period of time. The major problem encountered at the latter plant was that the process design did not provide an effective control on bacterial foaming, which had affected the smooth operation of the process.     

Experience with the preconstruction of thawing of soils in the foundation bed of the main building of the Neryungrinsk state area power plant

Conclusions 1. The scheme that we developed is efficient and ensures thawing over a period of 40–45 days. 2. To accelerate thawing by 8–10 days when using two electric heaters in each hole, it is necessary to raise the heaters by 3–4 m after 25 days and continue thawing. 3. An 8–10-day reduction in the thaw time is also possible by using three 1.25-kW electric heaters in each hole in place of two heaters of the same capacity, installing them at depths of 20, 14, and 8 m from the surface. Taking the results of the experimental work account, the State Institute for Special Design developed a plan for the production preconstruction thawing of soils over a area of 12,380 m². The volume of soil thawed was 324,400 m³. Translated from Osnovaniya, Fundamenty i Mekhanika Gruntov, No. 3, pp. 7–8. May–June, 1982.     

Hybrid reactor for priority pollutant-trichloroethylene removal

The present study was initiated to explore the potential of a hybrid biological reactor, combining trickling filter (TF) and activated sludge process (ASP), to treat wastewater containing trichloroethylene (TCE) at ambient temperature at different hydraulic retention time (HRT). The biofilm acclimation was achieved in 55-60 days with gradual increase in TCE concentration from 1 mg/l to 100 mg/l with a parallel increase in the concentration of substrate sodium acetate and other nutrients. COD and TCE concentration were taken as prime parameters for monitoring the growth of biofilm. During acclimation COD removal varied between 54.6-97.5% while TCE was removed 72.6-99.9%. HRT study was performed after acclimation. The removal efficiency increased with decreasing flow rate with maximum TCE removal (99.99%) at 6 l/d corresponding to an HRT of 28 h (TF 18 h + ASP 10 h). This was followed by a C:N:P ratio study. A ratio of 100:20:1 led to the sustenance of maximum TCE removal. Maximum TCE removal (99.99%) was observed at a substrate:cosubstrate ratio of 100:1. A pH of 7.4 +/- 0.2 was found to be optimum for degradation. Finally, volatilization losses were estimated to be 18.5%. A mass balance gave an efficiency of 81.51% for biological removal of TCE.     

Structural reliability software at the University of California, Berkeley

The paper provides an overview of three software for structural reliability analysis developed at the University of California, Berkeley. These are CalREL, which is a general-purpose structural reliability code written in FORTRAN; FERUM, which is a collection of Matlab^® files that can be used for structural reliability analysis in conjunction with simple finite element models; and OpenSees, which is an object-oriented code for nonlinear structural response simulation with reliability capabilities. Reliability analysis methods featured by these software include FORM, SORM, Monte Carlo simulation, and various importance sampling methods. In addition, variable importance and sensitivity measures are provided.     

Environmental exposure to lead and its correlation with biochemical indices in children

Lead is a global concern because of its ubiquity in the environment and known to be associated with abnormal neurobehavioral and cognitive development of young children. There is no study from India to describe a composite profile of blood lead and its biochemical influences in children. The present study was aimed at determining the proportion of children with >10 mug/dL blood lead levels (BLLs), association between BLLs, and sociodemographic characteristics, if any, and alterations in biochemical indices in the blood as an underlying mechanism of lead intoxication. A total of 62 children (4--12 y) of Lucknow and nearby areas were recruited to determine BLLs, delta-amimolevulinic acid dehydratase (delta-ALAD) activity, catalase (CAT) activity, and malondialdehyde (MDA) and glutathione (GSH) levels in the blood. Mean level of blood lead was 7.47+/-3.06 microg/dL (2.78--15.0) and 29%-exceeded 10 microg/dL, CDC intervention level. The BLLs were found to be significantly influenced by social status, area of residence, source of water supply, maternal educational status (p<0.001), type of house, and proximity to traffic density (p<0.01). delta-ALAD was significantly lower in the group of children with BLLs 11.39+/-1.39 microg/dL when compared to children with BLLs 7.11+/-1.25 microg/dL and 3.93+/-0.61 microg/dL (p=0.0007, 0.0005, respectively). However, CAT activity was higher in the groups of children with higher blood levels than with lower BLLs (p=0.0159, 0.0001, respectively). There was an increase in MDA level with a concomitant decrease of GSH in children with BLLs 11.39+/-1.39 microg/dL compared with those of children with BLLs 7.11+/-1.25 microg/dL and 3.93+/-0.61 microg/dL (p=0.0001, 0.0002, and p=0.0001, respectively). There was statistically significant correlation of BLLs with delta-ALAD (r=-0.44, p=0.00035), MDA (r=0.46, p=0.00018), GSH (r=-0.62, p=0.00001), and CAT (r=0.44, p=0.00035). Significantly, CAT activity, MDA, and GSH levels were in turn, found to be correlated with delta-ALAD (r=-0.45, p=0.00024; r=-0.43, p=0.00053; r=0.43, p=0.00053, respectively). Results of the present study indicate a declining trend of BLLs in children when compared with those reported from metropolitan cities of India when leaded gasoline was in practice and that the BLLs were significantly associated with biochemical indices in the blood which have the potential to be used as biomarkers of lead intoxication.