This study introduces an integrated system of direct contact membrane distillation (DCMD) and microalgae bioremediation for green removal of arsenic from the polluted river water. An inexpensive hydrophobic kaolin hollow fiber membrane (h-KHFM) was fabricated and used in the DCMD process for arsenic treatment on the polluted river water. The membrane demonstrates an excellent arsenic rejection of 100 % and a stable flux of 23.3 kg/m2h throughout the prolonged operation of 70 h. The performance of this membrane was compared with those of NF and RO; the results indicate superior performance of h-KHFM over the latter two processes in terms of permeate flux, arsenic rejection, as well as the performance flexibility and consistency at various pH conditions. The arsenic-rich retentate of the DCMD process is then bioremediated using Botryococcus sp. with an initial cell concentration of 1 × 106 cells/mL at the outdoor conditions. The findings show that Botryococcus sp. successfully grow in the retentate with a common microalgae growth pattern during the 20 days test period, which indicates the potential and feasibility of this integrated system for the arsenic retentate management. This study is pioneer and could provide an insight for the development of wastewater treatment technologies with zero waste discharge. © 2020 Elsevier B.V.

Cellulose biopolymer was converted to lactic acid by catalytic hydrothermal method. The conversion was studied under various temperatures (120 to 190 °C) and types of metal ion catalyst (Pb2+ and Al3+), while the reaction period remained fixed at 3 h. Following the reaction, the recovery of untreated cellulose and the mass loss were determined by gravimetric means. Meanwhile, the resultant liquid products were analysed by high performance liquid chromatography (HPLC) for detecting the targeted products: lactic acid, glucose, and fructose. The study reveals useful insights; elevating the reaction temperature was found to increase the mass loss, so did the yield of the targeted products. On the other hand, using a metal ion catalyst, possessing stronger Lewis acidity character, further enhanced lactic acid production. © Published under licence by IOP Publishing Ltd.

In this study, polycondensation of 88wt% lactic acid (LA) was performed by irradiating LA with microwave at different powers (P=250, 440, 715 and 900W) for 5 min, in the absence of a catalyst. The recovered products were analysed by attenuated total reflectance-infrared (ATR-IR) and thermogravimetric analysis (TGA). It was found that raising microwave power resulted in a significant increase in mass loss, even much higher than the water content of the fresh LA (12wt%). Such an observation was likely to be caused by two occurrences. The first is associated with the evaporation of 12wt% of water molecules in the fresh LA that escalated upon increasing microwave power. This is supported by ATR-IR analysis illustrating a decreasing trend in the intensity of O-H stretching band. The second is linked to the intensified polycondensation of LA to polylactic acid (PLA) when elevating microwave power, forming more ester bonds and consequently eliminating more water molecules. The increased formation ester bonds was evidenced by the shift in Tonset values towards higher temperatures, as exhibited by TGA profiles. As overall, the outcomes of this study could lead to a cost effective and energy saving production of biodegradable plastics, substituting the time-consuming conventional heating. � Published under licence by IOP Publishing Ltd.