Browsing by Author "Arumugam, Preyan."

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A critical assessment of the dendrochirotid subfamilies, sclerodactylinae and thyoninae, with the taxonomic management of the "supergenus" thyone (echinodermata : holothuroidea)
(2011) Arumugam, Preyan.; Thandar, Ahmed Suleman.
The key character separating the dendrochirotid families Sclerodactylidae (sensu Pawson & Fell, 1965) and the Phyllophoridae (sensu Pawson & Fell, 1965), i.e. entire or undivided radial processes to the calcareous ring in the former and sub-divided processes in the latter, is unjustified since most sclerodactylid species also have subdivided processes. It is here assumed that the basis of elevating the subfamily Sclerodactylinae Panning to family level was established on a misinterpretation or mistranslation of the original diagnosis of this subfamily or a lapsus calumni meaning “plates” instead of “processes”. Panning (1949) categorically states that the processes in the Sclerodactylinae are composed of 3–4 large pieces of calcite and only as an exception they are unbroken. Since Pawson & Fell gave no other distinction between the Sclerodactylidae and the Phyllophoridae, the former is here considered an invalid taxon and its three current subfamilies (Sclerodactylinae, Sclerothyoninae Thandar and Cladolabinae Heding & Panning) are re-assigned to the Phyllophoridae. This family now includes six subfamilies: Cladolabinae, Phyllophorinae Östergren, Sclerodactylinae, Sclerothyoninae, Semperiellinae Heding & Panning and Thyoninae Panning. The diagnosis of the Sclerodactylinae, restricted by Thandar (1989), is now modified to include also those forms whose radial and interradial plates may be slightly sub-divided but still form a short tube. Of the eleven genera placed within this subfamily subsequent to its erection, only ten of these remain. Neothyone Deichmann is a preoccupied name for which Lisacucumis is here proposed as a replacement. Thandar’s (1989) diagnosis of the Thyoninae is here accepted, however, the genus Thorsonia Heding is transferred to the Sclerodactylinae. Of the 66 nominal species which currently stand in the “supergenus” Thyone Jaeger, 10 are transferred to Havelockia Pearson within the Sclerodactylinae, while one species is regarded as a synonym of H. herdmani Pearson. In addition, six species are transferred to Stolus Selenka within the Thyoninae. Finally, three species are transferred to Sclerothyoninae, two within Sclerothyone Thandar and one within Temparena Thandar. Two species show an uncertain affinity to Thyone and are temporally removed from the genus. Furthermore, two species currently classified within Havelockia are transferred to Thyone. The now remaining 46 species are separated into seven groups based on the composition of their introvert deposits: tables only (8 spp.), rosettes only (5 spp.), tables and rosettes (21 spp.), tables and plates/?reduced tables (2 spp.), rosettes and plates/?reduced tables (3 spp.), plates only (2 spp.), or introvert deposits absent or unknown (5 spp.). Regrettably, no other character could be used in conjunction with the above to suggest at least sub-generic levels. Within the genus Havelockia, Cucumaria redimita Sluiter indicates an affinity with Pentamera Ayres. It is here transferred to this genus within the Thyoninae. Havelockia, now containing 17 species, is also revised. Keys, diagnoses and figures are provided for all nominal species now included in Thyone and Havelockia.
Decentralised sanitation to fill the gap in urban wastewater treatment within the eThekwini Municipality: a focus on tertiary treatment in vertical down-flow constructed wetlands.
(2022) Arumugam, Preyan.; Pocock, Jonathan.; Brouckaert, Christopher John.
South Africa’s bulk sanitation infrastructure is failing, and there is an urgent need to look at other appropriate sanitation solutions. Moreover, there is no data on the proportion of population with access to safely managed sanitation services, an indicator for the United Nation’s Sustainable Development Goal (SDG) 6.2.1a. In a safely managed sanitation service, the user is provided with an improved facility, not shared with other households, and the excreta is safely disposed in situ or transported and treated off-site. In the city of eThekwini, informal settlements spring up faster than services can be delivered, severely impacting on public health, the environment, and the social well-being of these communities. The eThekwini Municipality sees the benefits of decentralised sanitation solutions for in situ informal settlement housing upgrades, but the selected system needs to produce fully compliant effluent with the Department of Water and Sanitation’s (DWS) Revised General Authorisation (GA) limits for safe discharge to a water resource. Since 2010, a modular-designed demonstration-scale decentralised wastewater treatment system (DEWATS) for raw domestic wastewater from 84 households has been in operation in eThekwini. The DEWATS operates with no electricity or chemicals for treatment, but was designed according to European best practice, and not according to the community served (such as influent characterisation and hydraulic loading). This study evaluated the applicability of vertical downflow constructed wetlands (VFCWs) as the tertiary treatment module in DEWATS in four design configurations, to determine an appropriate design that can be applied for the formal housing upgrades where safe discharge of the final effluent is required. These designs, all receiving anaerobically treated domestic wastewater from the demonstration-scale DEWATS and operating in the field, were: 1. A single-stage demonstration-scale VFCW (design 1) compared to its hybrid configuration with a horizontal flow CW (HFCW) (design 2). 2. VFCWs with extended filter depths (1 m) consisting of 2-3 mm coarse sand media (at pilot-scale) (design 3). 3. Two-stage VFCWs (at pilot-scale, operating under field conditions) (design 4): a. First stage: 0.5 m filter depth consisting of 2-3 mm coarse sand media. b. Second stage: 0.6 m filter depth with 0.5-2 mm fine to coarse sand media. Neither design was able to produce fully compliant effluent for safe discharge to a water resource. Depth had no impact on the treatment efficiency of the pilot-scale single-stage VFCWs; although the design with a two-stage VFCW, adapted from the Austrian design, did achieve higher total nitrogen removal compared to single-stage VFCWs with/without extended filter depths. Overall, design 2 with the demonstration-scale hybrid CW design (VFCWHFCW) produced the highest quality effluent. However, nitrate-N removal was limited in the HFCW due to low residence times, mixed aggregate media, high dissolved oxygen (DO) concentrations and lack of available carbon as an energy source for denitrification. A plantbased carbon source from dried plant material of the invasive Giant reed, Arundo donax L., was used to augment the carbon availability for denitrifying bacteria within the HFCW. However, it is surmised that the DO concentration above 0.5 mg L-1 limited NO3-N removal. It is recommended that the DEWATS design with the hybrid CW system be redesigned according to the raw wastewater characterisation and media gradation within both CWs to ensure sufficient residence times, natural aeration in the VFCW, limited diffusion of oxygen into the HFCW, and increased availability of biodegradable chemical oxygen demand carbon for denitrification. Moreover, if the upgraded households are installed with urine diversion flushing toilets, then the nutrient load to the DEWATS will be reduced, potentially resulting in fully compliant effluent. Consequently, DEWATS will then be considered a safely managed sanitation service, allowing South Africa to track their progress against SDG 6.2.1a.