Safety control of waste cooking oil:transforming hazard into multifarious products with available pre-treatment processes

The increase in worldwide vegetable oil consumption has produced a large increase in hazardous waste cooking oil(WCO)production.The improper disposal of WCO has been a significant problem from both an environmental and economic perspective.Therefore,it is advantageous to transform WCOs into valuable products efficiently and effectively in order to contribute towards the establishment of a circular economy.In this review,the current state of WCO is discussed in relation to WCO production and valorisation.The valorisation rate of each country can be categorised into three groups related to the consumption of vegetable oil,production and valorisation of WCO,as well as the production,conversion and valorisation factors.Before any valorisation and processing of WCO can be carried out,pretreatments are crucially needed in refining and upgrading WCOs,specifically to reduce their free fatty acid(FFA)contents.This could help to produce refined WCOs with appropriate feedstock properties suitable for value-added applications in oleochemical industries.Hence,several pretreatment methods(e.g.,solid impurities removal,FFA reduction,moisture removal)have been summarized and evaluated in depth.The transformation of WCO into valuable products including alkyd resin,green solvent,soap,plastics and plasticizer are also reviewed.Recent technological advances have made WCO feasible as sustainable feedstocks for oleochemical production,but not limited to biofuel production which in turn maximizes the value of this hazardous waste and turns WCO into a sustainable source.

Nature’s fight against plastic pollution:Algae for plastic biodegradation and bioplastics production

The increased global demand for plastic materials has led to severe plastic waste pollution,particularly to the marine environment.This critical issue affects both sea life and human beings since microplastics can enter the food chain and cause several health impacts.Plastic recycling,chemical treatments,incineration and landfill are apparently not the optimum solutions for reducing plastic pollution.Hence,this review presents two newly identified environmentally friendly approaches,plastic biodegradation and bioplastic production using algae,to solve the increased global plastic waste.Algae,particularly microalgae,can degrade the plastic materials through the toxins systems or enzymes synthesized by microalgae itself while using the plastic polymers as carbon sources.Utilizing algae for plastic biodegradation has been critically reviewed in this paper to demonstrate the mechanism and how microplastics affect the algae.On the other hand,algae-derived bioplastics have identical properties and characteristics as petroleum-based plastics,while remarkably being biodegradable in nature.This review provides new insights into different methods of producing algae-based bioplastics(e.g.,blending with other materials and genetic engineering),followed by the discussion on the challenges and further research direction to increase their commercial feasibility.