Agamuthu P, Faizura Putri Nadzrul
Institute of Biological Sciences, University of Malaya, Kuala Lumpur, Malaysia.
Waste Manag Res. 2005 Apr;23(2):95-100. doi: 10.1177/0734242X05051045.
Plastic waste constitutes the third largest waste volume in Malaysian municipal solid waste (MSW), next to putrescible waste and paper. The plastic component in MSW from Kuala Lumpur averages 24% (by weight), whereas the national mean is about 15%. The 144 waste dumps in the country receive about 95% of the MSW, including plastic waste. The useful life of the landfills is fast diminishing as the plastic waste stays un-degraded for more than 50 years. In this study the compostability of polyethylene and pro-oxidant additive-based environmentally degradable plastics (EDP) was investigated. Linear low-density polyethylene (LLDPE) samples exposed hydrolytically or oxidatively at 60 degrees C showed that the abiotic degradation path was oxidative rather than hydrolytic. There was a weight loss of 8% and the plastic has been oxidized as shown by the additional carbonyl group exhibited in the Fourier transform infra red (FTIR) Spectrum. Oxidation rate seemed to be influenced by the amount of pro-oxidant additive, the chemical structure and morphology of the plastic samples, and the surface area. Composting studies during a 45-day experiment showed that the percentage elongation (reduction) was 20% for McD samples [high-density polyethylene, (HDPE) with 3% additive] and LL samples (LLDPE with 7% additive) and 18% reduction for totally degradable plastic (TDP) samples (HDPE with 3% additive). Lastly, microbial experiments using Pseudomonas aeroginosa on carbon-free media with degradable plastic samples as the sole carbon source, showed confirmatory results. A positive bacterial growth and a weight loss of 2.2% for degraded polyethylene samples were evident to show that the degradable plastic is biodegradable.
塑料垃圾是马来西亚城市固体废弃物（MSW）中第三大垃圾种类，仅次于易腐垃圾和纸张。吉隆坡城市固体废弃物中的塑料成分平均占24%（按重量计），而全国平均水平约为15%。该国的144个垃圾场接收了约95%的城市固体废弃物，包括塑料垃圾。由于塑料垃圾在50多年内都不会降解，垃圾填埋场的使用寿命正在迅速缩短。在本研究中，对聚乙烯和基于促氧化剂添加剂的环境可降解塑料（EDP）的可堆肥性进行了研究。在60摄氏度下进行水解或氧化处理的线性低密度聚乙烯（LLDPE）样品表明，非生物降解途径是氧化而非水解。重量损失了8%，并且如傅里叶变换红外（FTIR）光谱中显示的额外羰基所示，塑料已被氧化。氧化速率似乎受促氧化剂添加剂的量、塑料样品的化学结构和形态以及表面积的影响。在为期45天的实验中的堆肥研究表明，麦克德样品[含3%添加剂的高密度聚乙烯（HDPE）]和LL样品（含7%添加剂的LLDPE）的伸长率（降低率）为20%，完全可降解塑料（TDP）样品（含3%添加剂的HDPE）降低了18%。最后，在以可降解塑料样品作为唯一碳源的无碳培养基上使用铜绿假单胞菌进行的微生物实验显示了证实性结果。降解后的聚乙烯样品细菌生长呈阳性且重量损失2.2%，这明显表明可降解塑料是可生物降解的。
