Binaya Raj Shivakoti

Mass flows of perfluorinated compounds (PFCs) in central wastewater treatment plants of industrial zones in Thailand

Perfluorinated compounds (PFCs) are fully fluorinated organic compounds, which have been used in many industrial processes and have been detected in wastewater and sludge from municipal wastewater treatment plants (WWTPs) around the world. This study focused on the occurrences of PFCs and PFCs mass flows in the industrial wastewater treatment plants, which reported to be the important sources of PFCs. Surveys were conducted in central wastewater treatment plant in two industrial zones in Thailand. Samples were collected from influent, aeration tank, secondary clarifier effluent, effluent and sludge. The major purpose of this field study was to identify PFCs occurrences and mass flow during industrial WWTP. Solid-phase extraction (SPE) coupled with HPLC-ESI-MS/MS were used for the analysis. Total 10 PFCs including perfluorooctane sulfonate (PFOS), perfluorooctanoic acid (PFOA), perfluoropropanoic acid (PFPA), perfluorohexanoic acid (PFHxA), perfluoroheptanoic acid (PFHpA), perfluorohexane sulfonate (PFHxS), perfluoronanoic acid (PFNA), perfluordecanoic acid (PFDA), perfluoroundecanoic acid (PFUnA), and perfluorododecanoic acid (PFDoA) were measured to identify their occurrences. PFCs were detected in both liquid and solid phase in most samples. The exceptionally high level of PFCs was detected in the treatment plant of IZ1 and IZ2 ranging between 662-847ngL(-1) and 674-1383ngL(-1), respectively, which greater than PFCs found in most domestic wastewater. Due to PFCs non-biodegradable property, both WWTPs were found ineffective in removing PFCs using activated sludge processes. Bio-accumulation in sludge could be the major removal mechanism of PFCs in the process. The increasing amount of PFCs after activated sludge processes were identified which could be due to the degradation of PFCs precursors. PFCs concentration found in the effluent were very high comparing to those in river water of the area. Industrial activity could be the one of major sources of PFCs contamination in the water environment.

A comparative study of adsorption of perfluorooctane sulfonate (PFOS) onto granular activated carbon, ion-exchange polymers and non-ion-exchange polymers

Perfluorooctane sulfonate (PFOS) is the latest chemical categorized as persistent organic pollutants (POPs). PFOS appears in the environmental water and tap water in ng L(-1) level. The process of adsorption has been identified as an effective technique to eliminate PFOS in water. Three non-ion-exchange polymers (DowV493, DowL493 and AmbXAD4), two ion-exchange polymers (DowMarathonA and AmbIRA400) and one granular activated carbon (GAC) (Filtersorb400) were tested with regard to their sorption kinetics and isotherms at low PFOS concentrations (100-1000 ng L(-1) equilibrium concentrations). The sorption capacities at 1 microg L(-1) equilibrium concentration decreased in the following order: ion-exchange polymers>non-ion-exchange polymers > GAC, but at further low equilibrium concentration (100 ng L(-1)) non-ion-exchange polymers showed higher adsorption capacity than other adsorbents. In the case of sorption kinetics, GAC and ion-exchange polymers reached the equilibrium concentration within 4 h and AmbXAD4 within 10 h. DowV493 and DowL493 took more than 80 h to reach equilibrium concentration. AmbIRA400 was identified as the best filter material to eliminate PFOS at equilibrium concentration > 1000 ng L(-1). Considering both adsorption isotherms and adsorption kinetics, AmbXAD4 and DowMarathonA were recommended to eliminate PFOS at ng L(-1) equilibrium concentration.

Occurrences and behavior of perfluorinated compounds (PFCs) in several wastewater treatment plants (WWTPs) in Japan and Thailand

This study examines occurrences of 11 perfluorinated compounds (PFCs) in several wastewater treatment plants in Japan and Thailand. Surveys are conducted in eight wastewater treatment plants (WWTPs) in Japan and central WWTPs of five industrial estates (IEs) in Thailand. Samples are collected from all major treatment processes in order to understand the behavior of PFCs in WWTPs. PFCs are detected in all WWTPs in Japan and Thailand. Concentrations of PFCs even exceed several thousands ng/L in some WWTPs. PFOS, PFOA, and PFNA are mainly detected in WWTPs in Japan, while PFBuS, PFOA, and PFHxA are mainly detected in WWTP of IEs in Thailand. Even though some of the investigated WWTPs utilize biological treatment processes coupled with chlorination, ozonation, or activated carbon adsorption, they are found ineffective to remove PFCs. During the treatment process, PFCs are found to accumulate at exceptionally high concentration levels in the activated sludge of an aeration tank and returned activated sludge. Overall, the estimated total daily mass of discharged PFCs is 124.95 g/d (PFASs: 49.81 g/d; PFCAs: 75.14 g/d) from eight WWTPs in Japan and 55.04 g/d (PFASs: 12 g/d; PFCAs: 43.04 g/d) from five WWTPs in Thailand. Although the presented data are from a single observation in each WWTP, the results indicate that certain industries using PFCs in manufacturing processes could be the principle point source, while domestic activities could be releasing PFCs at detectable levels causing environmental concern.

Worldwide surveys of perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA) in water environment in recent years

Recently, perfluorinated compounds (PFCs) have been noted as causes of some of the important environmental problems in recent years due to their occurrences and properties. The most commonly used PFCs are perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA), which have been used in many kinds of products. They have been found in surface water and tap water in both developed and developing countries around the world including in North America, Europe and Asia. In most countries, rivers are the source of tap water, which is one of the important pathways in which PFCs reach humans. It is essential to evaluate PFOS and PFOA contamination in the river basin. The purpose of this field study was to determine the presence of PFOS and PFOA in rivers around the world. The surveys were conducted in 15 countries during 2004 to 2010. In total, 539 samples were collected from the rivers in 41 cities. A solid phase extraction (SPE) coupled with HPLC-ESI-MS/MS were used for the analysis of these chemicals. PFOS and PFOA were detected in all 41 cities not only in industrialized areas but also in non-industrialized areas, representing that these compounds undergo long-range transportation in the environment. The average concentration of PFOS in each city ranged from not detected to 70.1 ng/L. The average concentration of PFOA in each city was in the range 0.2-1,630.2 ng/L. The industrialized areas show higher contamination in both PFOS and PFOA concentrations than non-industrialized areas. Industrial activities are some of the major sources of PFCs contamination in rivers.

Perfluorinated compounds (PFCs) in Yodo River system, Japan

There is increasing concern about occurrences of perfluorinated compounds (PFCs) in the environment due to their persistent, bioaccumulation, and potentially toxic effects. We investigated contamination of 11 PFCs (C4-C12) in the Yodo River system, which is a major source of drinking water for more than 11 million people of Kansai region in Japan. PFCs were detected in higher concentration even exceeding more than 1000 ng/L in some cases. Composition profile of total PFCs concentration showed that PFOS, PFHxA, PFOA, and PFNA were occurring dominantly in the river system. PFOS and PFOA concentration were nearly proportional to a previous study in the same river system, indicating continuous sink of the compounds into the river system. Although discharge of PFCs from wastewater effluents at upstream could be one of the major point sources, concentration did not exceed 29.4 ng/L at the downstream of main Yodo River, possibly, due to dilution effects. Total mass load of PFCs in mainstream of Yodo River was estimated 451.7 g/d based on observed river discharge and PFCs concentration. Results showed that Yodo River system could have a unique upstream-downstream linkage of PFCs contamination and the river could be a continuous pathway of PFCs exposure to the people of Kansai region.

Water Environment in Central and East Asia: An Introduction

Abstract The Central and East Asian subregion consists of 10 countries covering an area of 15.45 million km2 (WB, 2015), within a geographical boundary of 18°N–56°N and 46°E–146°E. It is an extremely large subregion of varied geography, including high mountain passes, vast deserts, and treeless grassy steppes. The subregion stretches from the border with Russia in the north to the High Himalayas in the south, and from the Caspian Sea in the west to the East China Sea and Pacific Ocean in the east. Central Asia was the crossroads of the Great Silk Road, which saw the intermingling of cultures over hundreds of years, and it was also a cradle of civilization, leaving achievements in arts and architecture, science, philosophy, and literature for centuries to come. Despite the many-shared cultural, historical, and environmental features among the countries of the subregion, it is characterized by great contrasts in climate and topography. There are large variations among the subregional countries in terms of geographical area, climate, population size and density, and per capita income.