Introduction: Polyhydroxyalkanoates (PHAs) are natural polyesters and biodegradable plastics that are stored as intracellular inclusion bodies by a great variety of bacteria. The aim of this study was to extract polyhydroxyalkanoate from native Sino rhizobium meliloti in Iran.Materials and methods: Sino rhizobium meliloti isolates were collected from roots of alfalfa plants and were identified by Gram staining, biochemical experiments and amplification of 1500 bp fragment of 16Sr DNA gene. PHA granules were detected by microscopic examination. PHA production was evaluated in nutrient deficient medium and its amount was determined by conversion of PHA into crotonic acid by sulphuric acid treatment. The effect of various temperatures, agitation rate and carbon source (sucrose, mannitol, and maltose) were evaluated on dry cell weight and polyhydroxybutyrate (PHB) production.Results: The maximum amount of polymer production (43.10%) was seen in basal mineral medium at 29°C, pH~7 and 215 revolutions per minute (rpm). The results of this research showed that the S5 isolate was capable to produce maximum poly3- hydroxybutyrate. The produced polymer was analyzed for its purity by GC- mass (gas chromatography- mass spectroscopy) and confirmed to be PHB compared with the standard polymer.Discussion and conclusion: Native strains of Sino rhizobium can be used in the production of biodegradable plastics and the results of present study showed that S. meliloti S5 was capable to produce maximum PHB at 29°C, agitation rate of 215 rpm, and pH~7.

The study was undertaken with the objectives to: (1) Study the present status of plastic waste management and the existing Phnom Penh household willingness and their influence factors to segregate plastics for recycling and reuse (plastics & non plastics); (2) Study how other cities encouraged and obtained the participation of their population in plastics recycling and reuse and (3) recommend which policy the government should implement plastic waste recycling in Phnom Penh. The study was conducted in two phases. Phase one involved secondary research such as reviewing of relevant literatures, journals, publications, books, and reports. The second phase involved collection of primary data via structured questionnaires. The study is analyzed based on 429 qualified questionnaires that were collected from households in Phnom Penh by using: percentage, mean and standard deviation. It investigated household’s behavior toward their waste and their willingness to separate plastics and non-plastics wastes. The researcher considers the question of waste from households as it is most likely the root of waste behaviors. By looking at the current state of process and recycling plastics waste –an important element of waste equation, the researcher hopes to shed the lights on plastic waste issues.

The use of petroleum-derived plastics, especially pentagonal plastics (polypropylene, polyethylene, polyvinyl chloride, polystyrene and polyethylene terephthalate), provides numerous and significant social benefits. For example, plastics are used to package food, water and beverages and contribute to the health and safety of people all around the world. In addition to food, most personal items, cosmetics and household items are packed in plastic containers. However, the proliferation of plastic contamination is a global concern. "Reuse, Reduce and Recycle" offers a solution,although it is not enough to prevent the improper use of plastics. Bio-based plastics, like traditional fossil-based plastics, can be recycled or incinerated. The popularity of biodegradable plastics in agriculture and the food packaging industry is increasing. However, they occupy a relatively small portion of plastic use. Biodegradable polymers help industries achieve sustainable development, thereby strengthening the green economy, reducing greenhouse gases in the environment and valuing waste biomass. Biodegradable films are made of animal proteins (including myofibrillar proteins of fish, collagen, gelatin, etc. ), plants (rice, wheat, corn, barley, sunflower etc. ), legumes (locust beans, peas, etc. ), and aquatic plants such as macrophytes.

The paper reports the production of liquid fuels from waste plastics' thermal and catalytic pyrolysis, including polypropylene (PP), high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polystyrene (PS). For this purpose, three different types of zeolites (4A, ZSM-5, and 13X) and Cu/4A, Cu/ZSM-5, and Cu/13X were used in catalytic pyrolysis. The acidity and textural properties of the catalysts are the main parameters in the decomposition of polymers. The order of acidity of the catalysts was as follows: Cu/13X> Cu/4A> Cu/ZSM-5. The main product of thermal pyrolysis was liquid, mostly linear heavy hydrocarbons, whereas catalytic pyrolysis by copper/zeolite catalysts produced liquid products containing more branched hydrocarbons at lower temperatures. The liquid products carried out analysis through the use of FTIR and GC/MS techniques. The results indicated the presence of paraffin, olefins, and aromatic hydrocarbons in the liquid products. It was also found that light liquid hydrocarbons and gaseous products were produced over Cu/13X (higher acidity, large pore size, and high surface area). For Cu/4A, Cu/13X, and Cu/ZSM-5 catalysts, the main liquid products of catalytic pyrolysis were in the range of diesel, gasoline, and kerosene, respectively.