Volume 8 Issue 1

Authors: Sylvester M.Tongu; Rufus Sha’Ato; Jonathan O. Okonkwo; Olubiyi I. Olukunle; Ishaq S. Eneji; Terrumun A. Tor-Anyiin

Abstract: Polybrominated diphenyl ethers (PBDEs) have been recognised as persistent organic pollutants (POPs) and are also among chemicals classified as endocrine-disrupting compounds (EDCs) which interfere with the endocrine system and disrupt the physiological function of hormones in animals and humans alike. This study determined the concentrations of six PBDE congeners (BDE 47, BDE 99, BDE 100, BDE 153, BDE 154 and BDE 183) in water and sediment samples from River Benue, in the Makurdi Metropolitan Area in North Central Nigeria using gas chromatogragh – mass spectrometer. These congeners are components of the penta- and octaBDE formulations that have been banned by the European Union. The samples were collected from the River, bi-monthly, for one year across dry and wet seasons. All the congeners considered were found to be present in both water and sediment. The levels of Σ6PBDEs in water ranged from 0.02 – 0.11 ngL_1 during dry season and 0.10 – 0.76 ngL_1 during wet season while the concentrations in sediment during dry and wet seasons ranged from 4.65 – 26.74 ngg_1 and 4.40 – 17.15 ngg_1 respectively. The percentage recoveries from solid phase and Soxhlet extractions ranged from 68 – 111 % and 71 – 109 % respectively. It was concluded that the presence of all the congeners in both water and sediment coupled with their established environmental persistence and bioaccumulation posed a pollution risk to the river which requires further monitoring and preventive measures to be taken.

Keywords: Gas chromatograph – mass spectrometer; polybrominated diphenyl ethers; sediment; river water; Nigeria


Authors: Gjorgi Pavlovski; Radmila Bojkovska; Kole Pavlov

Abstract: The drainage basin of the Radika River is located in the western parts of the Republic of Macedonia and almost entirely belongs to the national park Mavrovo, which is also a treasury of geomorphologic, biological and cultural heritage. Waste water from households, catering facilities, as well as the developed economic activities in the fields of agriculture, cattle breeding and large tourist saturation are sufficient factors that would violate the quality of the Radika River, which is considered to be a protected and clean watercourse in the region, and wider in the country. According to the legal regulations in the Republic of Macedonia, the waters of Radika River in the national park Mavrovo shows solid summarized quality. Detected quality anomalies primarily express the organic burden as an anthropogenic source of pollution. The natural factors on the other hand, are not a major hazard to the aquatic ecosystem.

Keywords: Radika; Measuring Point; Pollution; Heavy Metals


Authors: Tadashi Hibino; Yusuke Sunada; Kaichi Nishimura; Satoshi Yamaji; Narong Touch

Abstract: It has been reported that solar cell-combined sediment microbial fuel cell (SC-SMFC) can be an alternative option for remediating sediment. Near a sewage outlet, huge amount of sediment accumulation causes many environmental problems, such as malodor and the restriction of benthos inhabitation. This study aims to employ SC-SMFC for remediating sediment deposited near a sewage outlet. Particularly, we aim to determine the remediation range of sediment from the anode of SC-SMFC. SC-SMFC was applied into the sediment deposited on the riverbank of a tidal river, and the distribution of sediment quality from the anode was examined at 14 weeks after the employment of SC-SMFC. Decreases in hydrogen sulfide, phosphate, manganese, and ammonium ion concentrations were found, indicating the sediment remediation owing the SC-SMFC application. A larger decrease in each ion concentration was found near the anode. From the ion distributions, the sediment located between 0 and 1 m from the anode was strongly influenced by the SC-SMFC application, which was approximately 6.7-fold longer than that obtained from the laboratory experiment. At in-situ, water current that can transport substances to the anode and the biodiversity of microorganisms that can produce much of electrons may partly contribute to the increasing SC-SMFC performance, leading to the long range of sediment remediation. Furthermore, it is newly found out that ammonium and manganese ions are efficiently removed from sediment via the anode oxidation during the SC-SMFC application.

Keywords: Solar Cell; Sediment Microbial Fuel Cell; Sediment Quality; Remediation Range; Hydrogen Sulfide, Ammonium


Authors: Tadashi Hibino; Yuki Morimoto; Manaka Okabe; Hiroki Takata; Narong Touch

Abstract: To date, granulated coal ash (GCA, a by-product from coal fired-power plants) has been widely used for improving sediment and water quality, such as removals of nutrient salts and hydrogen sulfide. These removal capacities of GCA lead us to consider that GCA can be used as a filter material in wastewater treatments. This study is aiming at examining the potential of using GCA as a filter material in wastewater treatments. One of our objectives is to examine how to use GCA for efficient removal of nutrient salts. Another objective is to propose filter design and operation of using GCA for removing nutrient salts effectively. Laboratory experiments were conducted under different conditions, such as different concentrations of nutrient salts and retention times. The experimental results showed a higher removal rate of ammonium ion when polluted water was retained in GCA filter compared to the circulating polluted water through the GCA filter. This was observed when the retention time shorter than 180 min. However, the removal rate was similar when the retention time was longer than 180 min. A higher solution pH in the retention condition was considered to partly contribute to the higher removal rate. Moreover, the absorbed quantity increased with an increase in the concentrations of nutrient salts. This pointed out that the removal of nutrient salts by GCA depends on the concentrations of nutrient salts present in the solution. According to these results, design of GCA filter and its operation were proposed. The GCA filter was divided into two different parts. The polluted water was retained in the first part for 90 min, then discharging to the second part for 90 min-retention. Compared with the filter without division (180 min-retention), 1.33-fold increases in NH4+ and 1.55-fold increases in PO43- removals were obtained owing to our proposed filter design and operation.

Keywords: Granulated Coal Ash; Filter Design; Removal; Nutrient Salts; Retention


Authors: Tadashi Hibino; Tomofumi Miyatsu; Kentaro Nagama; Satoshi Yamaji; Narong Touch

Abstract: It has been reported that solar cell-combined sediment microbial fuel cell (SC-SMFC) can be an alternative method for improving sediment and water quality. This study describes the employment of SC-SMFC for improving sediment and water quality in an oyster farm. The release of hydrogen sulfide from bottom sediment is one of the factors that cause the death of oysters which should be suppressed. At 3 months after the employment of SC-SMFC, bottom water (100 mm from the seafloor) and surface sediment (-100 mm from the seafloor) were collected and analyzed. The results showed decreases in hydrogen sulfide and phosphate concentrations in the sediment, indicating the improvement of sediment quality owing to the SC-SMFC application. In addition, the quality of bottom water was also improved owing to the SC-SMFC application. For example, the dissolved oxygen concentration and redox potential of the bottom water in the system-applied area remained higher comparing with those in the control area. These findings further strengthen that SC-SMFC is a highly effective method for suppressing the release of hydrogen sulfide and phosphate from sediment, which can protect water environment from hypoxia and eutrophication.

Keywords: Solar Cell; Sediment Microbial Fuel Cell; Hydrogen Sulfide; Dissolved Oxygen; Phosphate Fixation