نشریه پایداری، توسعه و محیط زیست
سال پنجم شماره 17 (بهار 1403)

The steel industry is one of the most hazardous process industries due to the nature of metal melting and high heat, gases and hazardous chemicals. The high potential of process incidents with consequences such as fire, explosion and release of toxic substances in the mentioned industry emphasizes the importance of hazard identification as the first step in process safety risk management. In the present research, to provide the necessary infrastructure, including a written methodology for hazard identification and risk analysis studies as one of the most vital requirements of Process Safety Management (PSM) and in line with PSM implementation in Mobarakeh Steel Company, the relevant procedure was developed and to ensure its applicability, process safety hazards and their associated incidents in one of the most hazardous units (oxygen and hydrogen unit) were identified and analyzed using the aforementioned procedure.

The “hazard identification and process safety risk analysis” procedure was developed in accordance with the requirements of process safety management expatiated in PSM best practices and other relevant technical documents. The procedure includes hazard identification (HAZID) worksheet, guide words, levels of probability of occurrence and severity of consequences, risk matrix, implementation methodology, etc. In order to conduct the HAZID study in the oxygen and hydrogen unit, a team including experts and experienced engineers in their relevant job fields was formed, and after preparing the necessary arrangements such as reviewing the documents, HAZID meetings were held according to the developed methodology, the worksheets were completed and analyzed as per the study nodes and relevant corrective measures were also suggested.

From the total of 40 process safety incidents identified in the oxygen and hydrogen unit, 5% had a low-risk level, 65% had a medium-risk level, 15% had a high-risk level and 15% had an extreme-risk level. Therefore, the majority of the identified process safety risks had a medium (tolerable) risk level. Major Process Incidents (MPIs) with high (unacceptable) and extreme (intolerable) risk levels also constitute 30% of all incidents. The plants of the oxygen unit had the most process incidents in terms of the number, and gas and liquid tanks had the highest risk level of process safety incidents. In total, 12 MPIs with high and extreme risk levels were identified.

One of the key achievements of the research is the development of the “hazard identification and process safety risk analysis” procedure in Mobarakeh Steel Company to identify and analyze the process safety incidents and other related characteristics such as the causes and consequences of incidents, prevention and mitigation controls, the probability of occurrence and severity of consequences, risk level, etc. Also, the aforesaid procedure would help deliver a coherent methodology for assessing process safety risks, provide a suitable platform for adopting corrective measures for major risks, conduct supplementary studies, and develop and implement other mechanisms required to meet PSM requirements.

A major challenge in global agriculture is to produce more food for another 2.3 billion people by 2050 worldwide. Salinity is a major stress that limits the supply of food products. The total land area is about 13.2 billion hectares, of which 7 billion hectares are arable and 1.5 billion hectares are under cultivation, and about 23% of the cultivated lands around the world (about 345 million hectares) are affected by salinity stress and its amount is increasing day by day. Plants can be classified into two types, halophytes (which can resist salinity) and glycophytes (which cannot resist salinity and eventually die), and most major crops belong to this second category. The purpose of this article is to review scientific research related to the effects, mechanisms of tolerance, research methods, important measurable traits, management and control of salinity and oxidative stress in agricultural plants.

This article is a review article that was obtained by searching related articles in reliable sites (Google scholar, Web of Science, PubMed, Scopus, SID.

Salinity have adverse effects on various plant characteristics such as physiological, metabolic, growth, germination, strength, quantity and quality of plants. The most important damages caused by salinity stress include ion imbalance due to reduced absorption of necessary ions, accumulation of harmful ions and dehydration due to decreased water absorption which reduces protein synthesis, transpiration, ion transfer and finally decreases seed yield. Mechanisms of salinity stress tolerance include ionic homeostasis, compatible salt accumulation and osmotic protection, antioxidant regulation, polyamines, nitric oxide, and hormonal regulation of salinity tolerance. Under stress, reactive oxygen species such as superoxide radicals, singlet oxygen and hydroxyl radical are produced, which damage cell structure, proteins, cell membranes, carbohydrates, nucleic acids, and eventually cause cell death.

Enzymatic or non-enzymatic antioxidants play a very important role in protecting plants against oxidative damage. Superoxide dismutase, catalase, peroxidase, ascorbate peroxidase, glutathione reductase are enzymatic antioxidants and ascorbic acid, glutathione, carotenoids and tocopherols are non-enzymatic antioxidants which can reduce the damage caused by reactive oxygen species.

Industrial wastewater treatment is more difficult than urban sewage due to the presence of various pollutants. Sewage produced in the leather industry should be treated to the environment due to having a pollution load and the presence of high chloride ion before discharge. The advanced oxidation process based on dioxy persulfate is considered a new process in the presence of active agents. This process has a great capability in wastewater treatment with high pollution. In this study, the anion process of persulfate was used with the activation of magnetic iron (Fe3O4) and zero-valent iron at laboratory scale in order to treat and reduce the organic load (COD) waste water of leather industry.

In this process, the effect of primary pH variables of wastewater (5-9), reaction time (0-60 minutes), Anion concentration of persulfate (50-200 mg per liter) and the amount of iron-containing nanoparticles (0.5-2 grams per liter) were investigated.

The best conditions of the advanced oxidation process in the presence of zero-valent iron include pH 3 ،The amount of magnetic iron nanoparticles was equal to one gram per liter and the amount of dioxy persulfate was equal to 100 mg per liter. During the mentioned conditions, the efficiency of the process was achieved by 85 percent. The findings revealed that the initial COD (COD process reduced 3,700 milligrams per liter to below 1,000 milligrams per liter COD final to 555 milligrams per liter.

Advanced oxidation process based on dioxy persulfate in the presence of iron compounds (zero-valent iron and magnetic iron) due to high performance (removal of 85 percent of primary COD and reduction to 555 milligrams per liter, can be used for decomposition and mineralization of pollutants, pollutants, water, especially industrial sewage. The effluent from this system can be drained into municipal wastewater treatment plants, so by reducing COD to 555 mg per liter, it still cannot be used alone.