Reclaimed water has been greatly applied worldwide recently to augment water supply for non-potable domestic purpose. The present study put an effect on assessing the application of ultra-filtration (UF) on advanced treatment following conventional domestic wastewater treatment and coal mining wastewater for reusing purpose. On-site advanced treatment pilots using UF membrane with the capacity of 1 – 1.5 m3/h were built to treat decentralized domestic wastewater which has a low concentration of organic matters and coal mining wastewater which is abated by chemical-physical process and advanced treatment train. Dissolved oxygen (DO), pH, Chemical oxygen demand (COD), biochemical oxygen demand (BOD), total suspended solids (TSS), volatile suspended solids (VSS), Total Nitrogen (TN) and ammonium-nitrogen (NH4-N) in domestic wastewater and TSS, iron (Fe), manganese (Mn), and hardness of coal mining wastewater were analyzed. The pollutants in domestic wastewater were reduced significantly as of 82% TSS, 86% BOD5, 82% COD, and 96% NH4-N. The removal efficiency in coal mining wastewater reached 93.5% TSS, 67% iron, 68% manganese, and 52% hardness. The analyzed parameters in permeate of both pilots met legislation thresholds of Vietnam technical regulation on domestic water quality, proving that reclaimed water treated by UF can be used for non-potable domestic purposes.

Constructed wetland (CW) is an ecological work that can treat wastewater in natural condition. Combining CW with other ecological wastewater treatment works can create a suitable low-cost treatment system for peri- urban areas. The climatic conditions in the Northern region are favorable for the growth of Cyperus alternifolius, one of the commonly planted tree in HFCW worldwide. Our study focuses on the growth of Cyperus alternifolius on HFCW to evaluate the removal efficiency of organic substances and nutrients (BOD5, N-NH4, N-NO3, P-PO4). The dynamical coefficients of decomposition of those matters were also identified. This research employed a wastewater treatment pilot with HFCW planted Cyperus alternifolius and other ecological facilities in a peri-urban area in the North of Vietnam. It was found out that Cyperus alternifolius grew well with a high growth rate. The growth of Cyperus alternifolius enhanced the conversion of organic substances (BOD5) and nutrients (NH4, NO3, PO4) with high decomposition kinetic coefficients. The kinetic coefficient (kBOD) of HFCW in this research was 0.214md−1 which is much higher than the recommendation of Design Standard TCVN 7957:2008. Domestic wastewater after being treated through CW satisfied level A of National technical regulation on domestic wastewater QCVN 14:2008/BTNMT.

This study aims to examine the characteristics and to assess the hazardous level as well as the reusability of sewage sludge and river sediment from To Lich River (TLR) basin, which is the largest wastewater catchment in Hanoi. Sludge samples were collected from six manholes along Tran Binh Trong (TBT) and Thai Ha (TH) sewers in rainy and dry seasons. Sediment samples were collected from seven sites near principal wastewater and storm water discharging points along TLR upstream in dry season. Parameters, such as pH, humidity, total ash, zinc (Zn), copper (Cu), lead (Pb), and cadmium (Cd) in sewage sludge were examined. Trace metals in TLR sediment, e.g. arsenic (As), mercury (Hg), lead (Pb), zinc (Zn), chromium (Cr), and cadmium (Cd) were analyzed. The results of sludge and sediment analysis were then compared with national environmental regulations for hazards and aquatic life preservation, and land use purposes, including QCVN 43:2012/BTNMT, QCVN 50:2013/BTNMT, QCVN 03-MT: 2015/BTNMT. The majority of examined parameters of sewage sludge, except ash content, are higher in dry seasons than in rainy seasons. Regarding hazardous level, all the investigated heavy metals in sewage sludge in dry and rainy seasons, respectively, as followings: 644 and 598 mg.kg-1 Zn, 146.5 and 127.3 mg.kg-1 Cu, 71.2 and 69.5 mg.kg-1 Pb, and 1.51 and 1.46 mg.kg-1 Cd, are below the legislated thresholds, thus, can be considered as nontoxic. Reusability of sewage sludge, however, should be considered since Zn exceeded permissible values for all of land use purposes. The concentration of As (0.659 mg.kg-1), Hg (0.03 mg.kg-1), Pb (4.07 mg.kg-1), Zn (81.3 mg.kg-1), and Cd (0.078 mg.kg-1) meets national standards on hazardous waste, and sludge from water treatment process, as well as to protect aquatic life and to be reused in anthropogenic activities. However, Cr concentration (157 mg.kg-1) is above those legislated thresholds, thus, unsuitable to be reused as land or fertilizer. With high concentration of several trace metals and humidity, drainage sludge from TLR basins should be treated to improve its reusability. Article history: Received 20 March 2018, Revised 05 April 2018, Accepted 27 April 2018