A review on the coal gasification wastewater treatment technologies: past, present and future outlook

The 1977-2015 literature on treatment of the coal gasification wastewater is reviewed. An overview based on ammonia and phenol recovery, biochemical treatments and advanced treatment technologies is presented with the purpose of unveiling the reasons behind problems of high concentration of persistent organic pollutants being added in the environment from coal gasification wastewater operations. A considerable list of various methods for chemical oxygen demand (COD) abatement, phenols, ammonia recovery and other significant recalcitrant organic contaminants removal from coal gasification wastewater (CGW) has been compiled. Their removal efficiencies under various conditions have been presented with emphasis in the key advances of the development of present corresponding technologies. A summary of the literature and statistical references (156) from the year 1977-2015 showed that phenol and ammonia recovery process is about 10%, Biological treatment process is about 46% and advanced treatment process about 19% of the references. It is evident from the literature survey that physicochemical, biological along with recently added integrated advanced treatment technologies have the potential to turn coal gasification wastewater into usable recycled water. More technology gap needs to be addressed in order not only to save on consumption of freshwater but could also lead to the protection of surface water bodies from contamination by precariously coal gasification wastewater at the global level. (C) 2016 Elsevier Ltd. All rights reserved.