Iranian Journal of health, safety andenvironment

348-354

Authors: Abooalfazl Azhdarpoor, Zahra Mohammadi, Mansoureh Dehghani

Wastewater sludge typically contains large amounts of water and organic materials; therefore, its stabilization and dewatering is of particular importance. In this study, Fenton oxidation process is used for stabilization and dewatering of sludge in the output of a wastewater treatment plant. To evaluate the sludge stabilization and dewatering, specific resistance to filtration (SRF), volatile organic compounds (VSS), total suspended solids (TSS), soluble chemical oxygen demand (SCOD) and heterotrophic bacteria were measured. During the experiment, the optimal values of various parameters such as pH (2-9), hydrogen peroxide (0.015- 0.18mol/L), Fe2+ (0.008- 0.1mol/L) and time (5 - 60 minutes) for optimum sludge dewatering and stabilization were investigated. The results showed that the highest percentages of SRF reduction and removal rates of SCOD, VSS and TSS were 99.48, 61, 42, and 41 percent respectively. These results were obtained in optimum pH 5, 0.05 mol/l Fe2+, 0.12 mol/l hydrogen peroxide, and the retention time of 15 minutes. The removal rate of heterotrophic bacteria increased with increasing dose of hydrogen peroxide, so that a removal rate of 84 percent was observed at a dose of 0.18 mol/l. In general, Fenton process can reduce volatile organic materials and chemical oxygen demand of the sludge resulting in its significant stabilization and dewatering. In general, Fenton process can reduce volatile organic materials and chemical oxygen demand of the sludge resulting in its significant stabilization and dewatering.

366-373

Authors: Malek Hassanpour

Numerous small recycling units of plastic wastes have been currently constructed heedless to study of economic indices in Iran. Pay attention to the prominent performance of the industrial sector for economic development and its priority for fortifying other sectors to implement job opportunities, survey of the economic indices beckon the stakeholders and industries owners. The main objective of this study was a survey of economic indices in small recycling unit of plastic wastes. Therefore, the practice of computing the economic indices was performed using empirical equations, professional experiences and observations in site of the industry in terms of sustainability performance. Current study had shown the indices values such as value-added percent, profit, annual income, breakeven point, value-added, output value, data value, variable cost of good unit and production costs were found 62%, $ 366558, $ 364292.6, $ 100.34, $ 423451.25, $ 255335.75, $ 678787, $ 389.65 and $ 314494.4 respectively. The breakeven point about 15.93%, the time of return on investment about 1.12 (13.7 months) were represented that this industry slightly needs long time to afford the employed capital and starts making a profit.

380-384

Authors: Ayoub Ghanbary sartang, Ehsanollah Habibi, Arezou Abbaspoor Darbandy

Work-related musculoskeletal disorders are the most prevalent work-related disorders and injuries and being the main cause of disability. This study was conducted to assessment of the prevalence of musculoskeletal disorders in worker company household appliances production. Posture analysis was evaluated by OWAS method and prevalence of musculoskeletal disorders by Nordic questionnaire. With evaluating musculoskeletal disorders among company household appliances production can intervention action to reduce musculoskeletal disorders was carried out. This cross-sectional study was performed on 100 workers of the appliance manufacturing industry. These Individuals were included 15 persons from foam injection workshop, 17 persons from molding workshop, 17 operators of presses, 17 persons from packaging, 17 person from cutting unit and 17 operators of rivet. The Nordic questionnaire was completed by Individuals for the organs of arm, back, leg and wrist and Posture analysis was performed by OWAS method. The data were analyzed using Spss software version 18 and descriptive statistics and Anova test. Nordic questionnaire results revealed that highest disorders were observed in the arm (25%), back (22%) and leg (21%). Also Anova test showed that was observed a significant correlation respectively between age and work experience with the prevalence of musculoskeletal disorders (p<0.02) (p<0.01). The results showed based on the level of risk OWAS for each job respectively, the highest level of risk associated with foam injection unit, packaging and cutting unit (risk level 4) and the lowest level of risk associated with molding workshop unit (risk level 2).The results of this study showed that household appliances Manufacturing workers due to the nature of their jobs are at risk of musculoskeletal disorders and Ergonomic interventions to do such as workstation redesign, reduced working hours, cycle of rest-work development.