“…Cr(VI) as well as some of the residual dyes are 14 non-biodegradable owing to their complex molecular structures, 15 especially the case of heavy metal complex dyes, which make them 16 more stable and resistant to bio-degradation [3,4] and photo- 17 degradation a swell [5]. Many of these complex compounds are also 18 toxic in nature and can cause direct destruction or affect capabilities 19 of various living organisms [6].…”