Municipal solid waste management in the Southern Province of Sri Lanka: problems, issues and challenges

This paper describes the problems, issues and challenges faced by Sri Lanka based on the outcome of a recent study conducted in the country's Southern Province. The study consists of a public survey, discussions with local authority staff involved in waste management, discussions with Provincial Council and Government officials, dialogue with local politicians, review of documents and field observations. The study revealed that only 24% of the households have access to waste collection and that in rural areas it was less than 2%. A substantial number of households in areas without waste collection expect local authorities to collect their waste. The study also showed that most sites in the province are under capacity to handle any increased demand. Urgent and immediate improvement of the waste disposal sites is necessary to meet the current demand for improved waste collection. The study also revealed that there is a high willingness of people for home composting.     

Biodegradation and bio-sorption of antibiotics and non-steroidal anti-inflammatory drugs using immobilized cell process

In the present study, the removal mechanisms of four antibiotics (sulfamethoxazole, sulfadimethoxine, sulfamethazine, and trimethoprim) and four non-steroidal anti-inflammatory drugs (acetaminophen, ibuprofen, ketoprofen, and naproxen) in immobilized cell process were investigated using batch reactors. This work principally explores the individual or collective roles of biodegradation and bio-sorption as removal routes of the target pharmaceuticals and the results were validated by various experimental and analytical tools. Biodegradation and bio-sorption were found as dominant mechanisms for the drug removal, while volatilization and hydrolysis were negligible for all target pharmaceuticals. The target pharmaceuticals responded to the two observed removal mechanisms in different ways, typically: (1) strong biodegradability and bio-sorption by acetaminophen, (2) strong biodegradability and weak bio-sorption by sulfamethoxazole, sulfadimethoxine, ibuprofen and naproxen, (3) low biodegradability and weak bio-sorption by sulfamethazine and ketoprofen, and (4) low biodegradability and medium bio-sorption by trimethoprim. In the sorption/desorption experiment, acetaminophen, sulfamethoxazole and sulfadimethoxine were characterized by strong sorption and weak desorption. A phenomenon of moderate sorption and well desorption was observed for sulfamethazine, trimethoprim and naproxen. Both ibuprofen and ketoprofen were weakly sorbed and strongly desorbed.     

Photocatalytic mechanisms of indoleamine destruction by the quinalphos metabolite 2-hydroxyquinoxaline: a study on melatonin and its precursors serotonin and N-acetylserotonin

The redox-active quinalphos main metabolite, 2-hydroxyquinoxaline, is particularly effective under excitation by light. We have studied the photocatalytic destruction of melatonin and its precursors, because the cytoprotective indoleamine has been detected in high quantities in mammalian skin. In photooxidation reactions, in which melatonin, N-acetylserotonin and serotonin are destroyed by 2-hydroxyquinoxaline, the photocatalyst is virtually not consumed. Rates of melatonin and serotonin destruction are not changed by the singlet oxygen quencher 1,4-diazabicyclo-(2,2,2)-octane, indicating that this oxygen species is not involved in the primary reactions, so that the persistence of 2-hydroxyquinoxaline has to be explained by redox cycling. This should imply formation of an organic radical, presumably the quinoxaline-2-oxyl radical, from which 2-hydroxyquinoxaline is regenerated by electron abstraction from indolic radical scavengers. Electron donation by 2-hydroxyquinoxaline is demonstrated by reduction of the 2,2′-azino-bis-(3-ethylbenzthiazolinyl-6-sulfonic acid) cation radical under ultrasound excitation. The compound 2-hydroxyquinoxaline interacts with the specific superoxide anion scavenger Tiron. Formation of oligomeric products from melatonin and serotonin is strongly inhibited by sodium dithionite. Products from photocatalytic indolamine conversion are predominantly dimers and oligomers. No kynuramines were detected in the case of serotonin oxidation, and melatonin's otherwise prevailing oxidation product N ¹-acetyl-N ²-formyl-5-methoxykynuramine, another cytoprotective metabolite, is only formed in relatively small quantities. The proportion between products from melatonin is changed by 1,4-diazabicyclo-(2,2,2)-octane: singlet oxygen, also formed under the influence of excited 2-hydroxyquinoxaline, only affects secondary reactions.     

Decomposition of perfluorocarboxylic acids (PFCAs) by heterogeneous photocatalysis in acidic aqueous medium

Decomposition of perfluorocarboxylic acids (PFCAs) is of prime importance since they are recognized as persistent organic pollutants and are widespread in the environment. PFCAs with longer carbon chain length are particularly of interest because of their noted recalcitrance, toxicity, and bioaccumulation. Here in this study, we demonstrate efficient decomposition of three important PFCAs such as perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA) and perfluorodecanoic acid (PFDA) by heterogeneous photocatalysis with TiO₂ as a photocatalyst in acidic aqueous solutions. The PFCAs were decomposed into shorter carbon chain length PFCAs and fluoride ions. Photoholes of excited TiO₂ generated upon UV-irradiation are found to be the oxidation sites for PFCAs. Therefore, creation and sustenance of these photoholes in the acidic aqueous medium has enhanced the decomposition of PFCAs. Heterogeneous photocatalytic treatment achieved more than 99% decomposition and 38% complete mineralization of PFOA in 7 h. The decomposition of other PFCAs was as high as 99% with a defluorination efficiency of 38% for PFDA and 54% for PFNA. The presence of perchloric acid was found to enhance the decomposition by facilitating the ionization of PFCAs. The oxygen present in the medium served both as an oxidant and an electron acceptor. The mechanistic details of PFCA decomposition and their corresponding mineralization are elaborated.     

Occurrence of perfluorinated compounds in the aquatic environment as found in science park effluent,river water,rainwater, sediments,and biotissues

The current article maps perfluoroalkyl acids (PFAAs) contamination in the largest Science Park of Taiwan. The occurrence of ten target PFAAs in the effluent of an industrial wastewater treatment plant (IWWTP), its receiving rivers, rainwater, sediment, and the muscles and livers of fish was investigated. All target PFAAs were found in effluent of IWWTP, in which perfluorooctane sulfonate (PFOS) (6,930 ng/L), perfluorohexyl sulfonate (PFHxS) (2,662 ng/L) and perfluorooctanoic acid (PFOA) (3,298 ng/L) were the major constituents. Concentrations of PFBS and PFOS in the IWWTP downstream areas have exceeded safe concentration levels of avian and aquatic life, indicating a potential risk to wildlife in those areas. In sediment samples, predominant contaminants were PFOS (1.5–78 ng/g), PFOA (0.5–5.6 ng/g), and perfluorododecanoic acid (PFDoA) (nd–5.4 ng/g). In biological tissue samples, concentrations as high as 28,933 ng/g of PFOS were detected in tilapia and catfish liver samples. A positive correlation for log (C _sediment/C _water) and log (C _tissue/C _water) was found. The concentration and proportion (percentage of all PFAAs) of PFOS found in biotissue samples from the Keya River (which receives industrial wastewater) were found to be much greater (200 times) than those of samples from the Keelung River (which receives mainly domestic wastewater). These findings suggest that the receiving aquatic environments and, in turn, the human food chain can be significantly influenced by industrial discharges.     

<Emphasis Type="SmallCaps">l</Emphasis>-5-hydroxytryptophan resets the circadian locomotor activity rhythm of the nocturnal Indian pygmy field mouse, <Emphasis Type="Italic">Mus terricolor</Emphasis>

We report that l-5-hydroxytryptophan (5-HTP), a serotonin precursor, resets the overt circadian rhythm in the Indian pygmy field mouse, Mus terricolor, in a phase- and dose-dependent manner. We used wheel running to assess phase shifts in the free-running locomotor activity rhythm. Following entrainment to a 12:12 h light–dark cycle, 5-HTP (100 mg/kg in saline) was intraperitoneally administered in complete darkness at circadian time (CT)s 0, 3, 6, 9, 12, 15, 18, and 21, and the ensuing phase shifts in the locomotor activity rhythm were calculated. The results show that 5-HTP differentially shifts the phase of the rhythm, causing phase advances from CT 0 to CT 12 and phase delays from CT 12 to CT 21. Maximum advance phase shift was at CT 6 (1.18 ± 0.37 h) and maximum delay was at CT 18 (−2.36 ± 0.56 h). No extended dead zone is apparent. Vehicle (saline) at any CT did not evoke a significant phase shift. Investigations with different doses (10, 50, 100, and 200 mg/kg) of 5-HTP revealed that the phase resetting effect is dose-dependent. The shape of the phase–response curve (PRC) has a strong similarity to PRCs obtained using some serotonergic agents. There was no significant increase in wheel-running activity after 5-HTP injection, ruling out behavioral arousal-dependent shifts. This suggests that this phase resetting does not completely depend on feedback of the overt rhythmic behavior on the circadian clock. A mechanistic explanation of these shifts is currently lacking.     

The impact of semiconductor, electronics and optoelectronic industries on downstream perfluorinated chemical contamination in Taiwanese rivers

This study provides the first evidence on the influence of the semiconductor and electronics industries on perfluorinated chemicals (PFCs) contamination in receiving rivers. We have quantified ten PFCs, including perfluoroalkyl sulfonates (PFASs: PFBS, PFHxS, PFOS) and perfluoroalkyl carboxylates (PFCAs: PFHxA, PFHpA, PFOA, PFNA, PFDA, PFUnA, PFDoA) in semiconductor, electronic, and optoelectronic industrial wastewaters and their receiving water bodies (Taiwan's Keya, Touchien, and Xiaoli rivers). PFOS was found to be the major constituent in semiconductor wastewaters (up to 0.13 mg/L). However, different PFC distributions were found in electronics plant wastewaters; PFOA was the most significant PFC, contributing on average 72% to the effluent water samples, followed by PFOS (16%) and PFDA (9%). The distribution of PFCs in the receiving rivers was greatly impacted by industrial sources. PFOS, PFOA and PFDA were predominant and prevalent in all the river samples, with PFOS detected at the highest concentrations (up to 5.4 μg/L).     

Simulation of Combined Best Management Practices and Low Impact Development for Sustainable Stormwater Management1

Damodaram, Chandana, Marcio H. Giacomoni, C. Prakash Khedun, Hillary Holmes, Andrea Ryan, William Saour, and Emily M. Zechman, 2010. Simulation of Combined Best Management Practices and Low Impact Development for Sustainable Stormwater Management. Journal of the American Water Resources Association (JAWRA) 1-12. DOI: 10.1111/j.1752-1688.2010.00462.x Abstract: Urbanization causes increased stormwater runoff volumes, leading to erosion, flooding, and the degradation of instream ecosystem health. Although Best Management Practices (BMPs) are used widely as a means for controlling flood runoff events, Low Impact Development (LID) options have been proposed as an alternative approach to better mimic the natural flow regime by using decentralized designs to control stormwater runoff at the source, rather than at a centralized location in the watershed. For highly urbanized areas, LID practices such as rainwater harvesting, green roofs, and permeable pavements can be used to retrofit existing infrastructure and reduce runoff volumes and peak flows. This paper describes a modeling approach to incorporate these LID practices in an existing hydrologic model to estimate the effects of LID choices on streamflow. The modeling approach has been applied to a watershed located on the campus of Texas A&M University in College Station, Texas, to predict the stormwater reductions resulting from retrofitting existing infrastructure with LID technologies. Results demonstrate that use of these LID practices yield significant stormwater control for small events and less control for flood events. A combined BMP-LID approach is tested for runoff control for both flood and frequent rainfall events.     

Novel bacterial consortia isolated from plastic garbage processing areas demonstrated enhanced degradation for low density polyethylene

Environmental Science and Pollution Research - This study aimed to formulate novel microbial consortia isolated from plastic garbage processing areas and thereby devise an eco-friendly approach for...     

Effects of water washing on removing organic residues in bottom ashes of municipal solid waste incinerators

Due to their potential toxicity and odourous nature, the residual organics in municipal solid waste incinerators are recently gaining attention as an important issue of resources recovery apart from their complex mixture of organic counterpart. Studies of the organic fractions in municipal solid waste incinerator residues have been limited. In this study, extended solid-phase extraction of the water-washed bottom ash and liquid-phase extraction of the washing water were carried out with regard to bottom ash samples from three mass-burning incinerators in Taipei County (Taiwan) during four consecutive seasons of year 2008-2009. Supercritical fluid extraction and Soxtec extraction techniques along with GC-MS were successfully used to characterize the residual organics in weathered and washed bottom ashes. Supercritical fluid extraction provided the quantification of aliphatics and aromatic compounds such as hexanoic acid and benzaldehyde, respectively. Soxtec extraction was useful for qualitative analysis of aromatic and aliphatic groups in the ashes and many of which were odourous and toxic compounds. By mixing one unit weight (g) bottom ash with two unit volume (mL) water for 15 min, total organic carbon in the bottom ash was greatly reduced (e.g., from 4.1 to 1.8 wt.%). Among the removed were foul odour-causing compounds such as pyridine and quinoline derivatives, while some aromatic compounds such as 4-hydroxybenzaldehyde and low-molecular-weight aliphatics such as hexanoic acid remained. The results here suggest that washing with water can be an effective pre-treatment step for removing odour-causing and environmental concerned organics.