A charge model for household waste management services: a case study of Tehran municipality

In practice, it is difficult to implement Pay-As-You-Throw charge systems based on accurate estimates of waste generation. In many cities, this is made impossible, due to lack of technical and administrative infrastructure and cultural considerations, especially in developing countries. This paper presents an alternative two-component charge model that is the combination of cost-accounting technique of Waste Management Services (WMSs) and econometric functions of waste generation. Practical and computation steps considered by the model are presented as a proposal to reform the current system of waste charge in Tehran municipality. The presented model is simple to implement and resolves some of the disadvantages of the traditional methods of waste charge systems, including insufficient revenue to cover the cost of waste management and unfairness related to social inequality.     

Qualitative Study of Organic Compounds in Wastewaters of a Swine Slaughterhouse

The main purpose of this work was the preliminary qualitative study of organic compounds in wastewaters of swine slaughterhouses. The samples were collected in a local abattoir and submitted to Liquid-Liquid Extraction (LLE) and Solid-phase Extraction (SPE) with XAD-4^TM resin as stationary phase. The instrumental analysis was performed by Gas Chromatography with Mass Spectrometer Detector (GC/MSD). The compounds present in the LLE and SPE extracts were identified by the GC/MSD library (Wiley). The results pointed out that SPE and LLE can extract practically the same classes of compounds at the same amounts. LLE works well for the extraction of polar organic compounds, with acidified samples, while SPE presents a better performance for the extraction of less polar organic compounds. Aldehydes were main class of the compounds extracted by SPE and LLE and decenal was the major aldehyde identified. Fatty alcohols and carboxylic acids were also identified but in minor proportions.     

Association between psychosocial,organizational and personal factors and prevalence of musculoskeletal disorders in office workers

The purpose of this study was to investigate the relationship between organizational and personal (individual) factors with the prevalence of musculoskeletal disorders (MSDs) in office workers of the Iranian Gas Transmission Company. The participants rated two questionnaires – the standardized Nordic Musculoskeletal Questionnaire to measure the prevalence of MSDs, and the Veterans Healthcare Administration All Employee Survey questionnaire (2004 version) – to measure psychosocial, organizational and individual aspects of job satisfaction and workplace climate. The highest prevalence of MSDs was found in the lower back (49.7%) and neck (49.0%) regions. Results of the logistic regression models showed that some psychosocial and organizational factors and also some individual factors were associated with prevalence of MSDs (p < 0.05).These ?ndings illustrate the need to consider all elements of the work system as a whole in future studies and in organizational planning.     

EFFECTS OF STORM PATTERNS ON RUNOFF HYDROGRAPHS1

ABSTRACT: As an alternative to the conventional single-peak design storms commonly used in hydrologic practice, a large number of Southeastern Pennsylvania storm events were selected from hourly U.S. National Oceanographic and Atmospheric Administration (NOAA) records, and their temporal distributions were analyzed. From these recorded events, design storms of a typical distribution were developed for storm durations between 6 and 18 hours. All of these generated design storms have two or more peaks. The conventional single peak as well as the “typical” multi-peak storms were then applied to a simulated watershed. It was found that the multi-peak storms consistently produced more dispersed hydrographs with lower runoff peaks than the conventional single peak storms.     

Challenges in building resilience engineering (RE) and adaptive capacity: A field study in a chemical plant

Safety issue in a chemical plant is absolutely critical because loss of control can result in a catastrophic consequence which is not limited to the boundaries of the plant. Thus, a risk assessment system is required for (a) preventing accidents by anticipation, (b) surviving disturbances by recovery, and (c) handling disruptive events by adaptation. RE is a proactive approach claiming to achieve all these objectives. The present research tries to identify challenges in the procedure of building RE and its adaptive capacity in a chemical plant. Primary data were collected through on-site observations and interviewing personnel. The results indicated the main challenges could be classified into nine categories of: lack of explicit experience about RE, intangibility of RE level, choosing production over safety, lack of reporting systems, ‘religious beliefs’, out-of-date procedures and manuals, poor feedback loop, and economic problems. Finally, it is concluded that the management insight about safety in such systems should avoid hindsight bias and tend to create foresight. Changing this insight can lead to achieve high reliability and resilience in the plant.