Interaction of pharmaceutical & personal care products (PPCPs) and endocrine disrupting contaminants (EDCs) with microbial communities in South African wastewater treatment works and environmental waters
Archer, Edward (2018-03)
ENGLISH ABSTRACT: Global surface waters are increasingly shown to be contaminated by anthropogenic chemical pollutants which, in turn exert potential lethal- and sub-lethal toxicity risks to the aquatic environment and humans. In particular, pollutants which are able to modulate endocrine system pathways, known as endocrine disrupting contaminants (EDCs) are of an emerging global concern. Treated wastewater discharge is a major contributing source of this pollution, with the recalcitrance and passage of various contaminants through wastewater treatment posing a risk to water security. This is highlighted as a critically important global challenge which need to be further addressed, especially for developing countries that are subjected to increased demands for clean water and sanitation services due to rapid population growth and urbanisation. Furthermore, routine monitoring and refinement of analytical methodologies for risk assessment are largely limited in the country, which points to the needed to assess the harmful impact of priority micro-pollutants in surface water systems. One of the aims of the present study was to assess the presence and fate of EDCs and other emerging contaminants (ECs) within a selection of South African wastewater treatment works (WWTWs) and associated environmental waters in order to refine the monitoring tools and methodology used for risk assessment approaches. Endocrine-disrupting activities generated by in vitro steroid hormone receptor binding assays, namely the yeast (anti)estrogen screen (YES/YAES), highlighted the complexity when dealing with environmental samples containing a mixture of analytes. Even though notable reductions of estrogenicity by the WWTWs were measured, some remaining loads in effluent receiving river waters remained above risk-based trigger values, therefore potentially compromising human- and aquatic health. Estimation of the potential toxic masking by analytes with anti-estrogenic effect/activity highlighted further refinement that will be needed evaluating potential endocrine disrupting activity when applying bioassays for risk assessment. Both diurnal as well as seasonal variation in endocrine disrupting activities were recorded and discussed. Also, treated wastewater effluent served as a diluting medium to lower estrogenicity within recipient river waters at some study sites, and highlighted the contribution of alternative pollution sources that may significantly impact the quality of river systems. Although EDCs are mostly assumed to be associated with steroid hormones, in the present study I conducted scoping studies at selected WWTWs and showed the extent of regularly-used pharmaceuticals & personal care products (PPCPs) and drugs of abuse (DOA) present within wastewater and surface waters - having variable degradation profiles during wastewater treatment. In particular, ECs which were highlighted as priority micro-pollutants, such as anti-epileptics, non-steroidal anti-inflammatory drugs (NSAIDs), opioids and anti-depressants showed moderate- to negative removal during wastewater treatment, even during advanced activated sludge treatment processes. Although all of these pollutants are known to undergo biological degradation, the present study recommended further refinement of current treatment processes to improve on the removal of such persistent ECs. The need to define the environmental impact of EC breakdown-products were also discussed, as their potential health risks are largely unknown. The dissertation also showed the value of urban water profiling to report on the use and abuse of licit and illicit DOA within communities connected to sewer networks at two study sites. Several prescription and over-the-counter (OTC) medications were detected within wastewater originating from domestic sewage, in particular opioids, an anaesthetic and anti-depressant drug – all of which are reported to be abused in South Africa, although limited statistics exist. For illicit DOA, the loads of cocaine, 3,4-methylenedioxymethamphetamine (MDMA), methamphetamine, heroin and the new psychoactive substance (NPS) mephedrone confirmed their consumption within the communities connected to the WWTWs, which were enriched by including the detection of their metabolic breakdown products, as well as enantiomeric profiling of the chiral drugs. The present study encapsulated the benefit of urban water profiling to address current- and emerging global challenges for environmental- and human sustainability. Incorporation of the research outputs from the current study during refinement of risk-based approaches in South Africa may greatly improve water reclamation and management strategies to ultimately safeguard this valuable commodity for driving community- and environmental resilience.
AFRIKAANSE OPSOMMING: Oppervlak water regoor die wêreld word toenemend besoedel deur menslike chemiese besoedelstowwe, wat verder getoon word om verskeie dodelike en sub-dodelike toksisteitsrisikos te veroorsaak in die akwatiese omgewing en mense. Besoedelstowwe wat in staat is om endokriene stelsels te belemmer, wat bekend staan as endokrien-versteurende verbindings (EVVs) is veral wêreldwyd van ‘n opkomende besorgdheid. ‘n Hoof bydraende bron van sulke besoedelstowwe is afkomstig van behandelde afvalwater wat na die omgewing lei, waar stowwe wat nie voldoende afgebreek word nie ‘n groot risiko vir water sekuriteit bied. Hierdie is ‘n krities-belangrike internasionale uitdaging wat verder aangespreek moet word, veral vir ontwikkelende lande wat onderworpe is aan verhoogde eise vir skoon water en sanitêre dienste as gevolg van vinnige bevolkingsgroei en verstedeliking. Roetiene monitering en verfyning van analitiese metodes om risikobepaling te doen is ook grootliks beperk in die land, wat dus die behoefde uitwys om die skadelike impak van prioriteit besoedelstowwe in oppervlakswaters te assesseer. Een doel van die studie was dus om die teenwoordigheid en lot van EVVs en ander opkomende kontaminante (OKs) te assesseer in verskeie Suid-Afrikaanse afvalwaterbehandelingswerke en die geaassosieerde omgewingswaters om ten einde die moniterinsinstrumente en metodes wat gebruik word vir risikobepaling te verfyn. Endokriene ontwrigsaktiwiteiete wat gemeet was deur ‘n in vitro steroïedhormoon reseptorbindingstoets genaamd die gis (anti)oestrogeen toets (YES/YAES) het die kompleksiteit beklemtoon wanneer omgewingsmonsters, wat ‘n mengsel van komponente besit, gehanteer word. Alhoewel 'n noemenswaardige vermindering van oestrogenisiteit gemeet was gedurende afvalwaterbehandeling het sommige oorblywende vragte in uitvloeiselwater bo risiko-gebaseerde snellerwaardes gebly, wat verwys word om potensieël die mens- en watergesondheid te beïnvloed. Bepaling van die potensiële toksiese maskering van anti-oestrogeniese effekte/aktiwiteite het die nood van verdere verfyning gemerk as sulke toetse gebruik word vir risikobepaling. Beide seisoenale, sowel as daaglikse variasies in endokriene ontwrigtingsaktiwiteite by die verskillende studie terreine was ook bespreek. Dit was ook gewys dat behandelde afvalwater soms dien as 'n verdunningsmiddel om oestrogenisiteit in ontvanklike rivierwater te verminder. Die bydrae van alternatiewe besoedelingbronne wat die kwaliteit van rivierstelsels aansienlik kan beïnvloed was ook uitgelig. Alhoewel EVVs meestal geassosieer word met steroïed hormone het ek verder omvangsbepalingstudies by geselekteerde afvalwaterbehandelingswerke gedoen. Die omvang van gereeld-gebruikte farmaseutiese- en persoonlike versorgingsprodukte asook dwelmmiddels was aangetoon. Hierdie stowwe het baie variasie in hul afbrekingsprofiele gewys binne die verskeie afvalwaterbehandelingswerke. OKs wat veral uitgelig was as prioriteits kontaminante, insluitend anti-epileptiese stowwe, nie-steroïdale anti-inflammatoriese middels (NSAIMs), opioïede en anti-depressante het matige- tot negatiewe verwydering getoon tydens afvalwaterbehandeling, selfs vir werke wat gevorderde geaktiveerde slykbehandeling prosesse gebruik. Alhoewel al hierdie besoedelstowwe bekend is dat hulle biologies afgebreek kan word, dui die studie daarop dat verdere verfyning van huidige behandelingsprosesse gedoen kan word om ten einde die behandeling van OKs te verbeter. Die behoefte om die omgewingsimpak van OK-afbreekprodukte te ondersoek was ook bespreek, aangesien hul potensiële gesondheidsrisiko's grootliks onbekend is. Die verhandeling het ook die waarde van stedelike waterprofiel studies gewys om te rapporteer op die gebruik en misbruik van beide wettige en onwettige dwelmmiddels binne gemeenskappe wat aan rioolsisteme verbind is in twee studie areas. Verskeie voorskrif- en oor-die-toonbank (ODT) medikasies was opgespoor in afvalwater wat afkomstig is van huishoudelike rioolwater, veral opioïede, 'n narkose- en anti-depressante middel – waar al hierdie stowwe uitgelig word vir hul misbruik in Suid Afrika, alhoewel beperkte statistieke bekombaar is. Die teenwoordigheid van die onwettige dwelmmiddels kokaïen, 3,4-metielendioxymetamfetamien (MDMA), metamfetamien, heroïen en die nuwe psigoaktiewe stof (NPS) mephedrone in afvalwater het die gebruik van hierdie dwelms in die gemeenskap bevestig, wat verder verryk was deur die teenwoordigheid van hul metaboliese afbreekprodukte, sowel as enantiomeriese profilering van die chirale middels te ondersoek. Die huidige studie het die samevattende voordele van stedelike waterprofiel studies uitgelig om huidige- en ontluikende globale uitdagings vir omgewings- en menslike volhoubaarheid aan te spreek. Deur die verfyning van risiko-gebaseerde benaderings te oorweeg wat uitgelig was in die huidige studie kan dus tot verbeterde waterherwinning en bestuurstrategieë lei om hierdie waardevolle kommoditeit te beskerm wat grootliks verantwoordelik is vir gemeenskaps- en omgewingsveerkragtigheid.
Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/103343