Investigating the effect of wine and distillery wastewater on the efficacy of an upflow anaerobic sludge blanket (UASB) and enhancing biomass immobilisation by the addition of magnetisable foam glass particles (MP)

Buys, Wendy Yvonne (2015-12)

Thesis (MSc Food Sc)--Stellenbosch University, 2015.

Thesis

ENGLISH ABSTRACT: The wine and distillery industry is one the largest contributors in the production of wastewater worldwide. The effluent produced from this industry is classified as high strength wastewater and does not comply with local regulations. Treatment of these effluents is therefore mandatory if it is to be reused or pumped back into the ecosystem. The upflow anaerobic sludge blanket (UASB) has been found to be one of the most successful technologies in treating high strength wastewater, particularly wine and distillery wastewater. Therefore the first objective of this study was to investigate the effect of combined wine, marula and Brandy wastewater on the operation and efficacy of a UASB reactor. In order to simulate the production seasons of the three different waste streams, a feeding strategy was developed where the trial was divided up into different phases. The chemical oxygen demand (COD) reduction percentage throughout each phase remained at an average of 85% and above, as the organic loading rate (OLR) increased from 1 kg COD.m-3.d-1 (phase one) to 10 kg COD.m-3.d-1 (phase four). The biogas production increased from an average of 0.6 L.d-1 (phase one) to 10 L.d-1 (phase four) as well as the methane percentage that showed a similar trend; as the OLR increased throughout the trial so did the methane percentage. The pH and the alkalinity remained stable throughout the trial; however as the OLR reached 6 kg COD.m-3.d-1 some difficulties did occur as the pH dropped to below 5. The reactor was therefore monitored more closely as the OLR increased.The success of the UASB reactor is found in the retention of anaerobic bacteria that are responsible for the digestion of the substrate. Retention occurs as the anaerobic sludge forms aggregates, also referred to as granules, which can withstand the upflow velocity of the incoming substrate. The loss in biomass does however still occur. Therefore the second objective of this study was to investigate whether added magnetisable foam glass particles (MPs) would be a viable medium for biomass attachment to aid in the immobilisation of granular biomass. The third objective was to investigate whether the added MPs would affect the operation and efficacy of the UASB reactor. Scanning electron microscopy (SEM), fluorescent microscopy analysis and activity tests were done on the MPs after a seven month period within a UASB reactor. SEM results showed microbial attachment and colonisation on the surface of the MPs, a distinct difference was found when comparing an uncolonised MP to a fully colonised MP. A fully colonised particle displayed a large variety of organisms attached to its surface and the morphology of these organisms gave an indication that methanobacterium, methanoplanus, methanosaeta, methanobrevibacterium and methanosarcina were present on the surface of the MPs. The attachment and colonisation of bacteria onto the surface of the MPs were confirmed by the results obtained by the fluorescent microscopy analysis. Fluorescence was found after the particles were stained with SYTO 9, a green fluorescent dye that stains the nucleotides of bacterial cells. These results confirmed colonisation of a mixed consortium of bacteria onto the surface of the MPs. Methanogenic attachment was confirmed by autofluorescence; as the MPs were exposed to specific wavelengths of UV a blue colour was observed where methanogenic attachment occurred. Activity tests were performed to investigate whether the MPs produced biogas and methane. Biogas production was found in all three mediums used, which again confirms both the presence of acidogenic as well as methanogenic activity. With the addition of the MPs to the one UASB reactor (RMP), there was no initial influence on the operation of the reactor, however as the OLR reached 6 kg COD.m-3.d-1 and above the pH and alkalinity of Rcontol decreased significantly on three different occasions during the trial whereas this was not found in RMP. Another difference between RMP and Rcontrol was found at the end of the trial when the granular biomass was removed from the reactor. The granules in Rcontrol were much larger the granules from RMP, furthermore the majority of the biomass was in a floccular form rather than granular. Based on the data from this study the digestion of combined wine and distillery effluent is possible, however the reactor should be carefully monitored as the OLR increased above 6 kg COD.m-3.d-1. This study has also proven that using MPs as a medium to improve biomass retention is a viable option, furthermore the addition of MPs to a UASB reactor might have a positive effect on the digestion of high strength wine and distillery wastewater.

AFRIKAANSE OPSOMMING: Industrieë wat wyn en gedistilleerde produkte produseer lewer wêreldwyd een van die grootste bydraes tot die produksie van afloopwater. Die afloop wat geproduseer word deur hierdie industrieë word geklassifiseer as hoë sterkte afvalwater en voldoen nie aan die plaaslike regulasies nie. Behandeling van hierdie water is dus verpligtend as die water hergebruik gaan word of as dit in die ekosisteem teruggepomp gaan word. Daar is bevind dat die opvloei-anaërobiese slykkombers (OAS) reaktor een van die mees suksesvolle tegnologieë is in die behandeling van hoë sterkte afvalwater, veral by die afloop van wyn en gedistilleerde produkte. Die eerste doel van hierdie studie was dus om die uitwerking van gemengde afloopwater van wyn, brandewyn en maroela op die werking en doeltreffendheid van ‘n OAS reaktor te ondersoek. Om die seisoenale produksie van die verskillende afloopwaters te simuleer is ‘n voerstrategie ontwikkel waar die toets in verskillende fases verdeel is. Die gemiddelde chemiese suurstofbehoefte (CSB) reduksie persentasie van elke fase was 85% en hoër soos wat die organiese ladingstempo (OLT) verhoog is van 1 kg CSB.m-3.d-1 (fase een) tot 10 kg CSB.m-3.d-1 (fase vier). Die biogas produksie het van gemiddeld 0.6 L.d-1 (fase een) tot 10 L. d-1 (fase vier) verhoog soos wat die OLT verhoog is deur die loop van die toets, en die metaan persentasie het ‘n soortgelyke tendens getoon. Die pH en alkaliniteit het stabiel gebly deur die loop van die toets, maar soos wat die OLT verhoog het tot by 6 kg CSB. m-3.d-1 en hoër het die pH en alkaliniteit egter fluktuasies begin toon. Die reaktor is dus meer deeglik gemonitor soos wat die OLT verhoog het. Die OAS reaktor se sukses word gevind in die vermoë daarvan om die anaërobiese bakterieë wat vir die vertering van die substraat verantwoordelik is te behou. Die behoud van die anaërobiese bakterieë vind plaas soos wat granulasie, of die vorming van sferiese biofilms, plaasvind. Hierdie granules kan die opwaartse vloei van die inkomende substraat weerstaan. Die verlies in biomassa vind egter steeds plaas. Dus was die tweede doel van hierdie studie om vas te stel of magnetiese skuimglaspartikels (MPs) wat by die OAS reaktor gevoeg word ‘n geskikte medium sou wees waarop die anaërobiese biomassa kan groei. Die derde doel van hierdie studie was om vas te stel of die bygevoegde MPs ‘n invloed op die OAS reaktor se werking sal hê. Skandeer-elektron mikroskopie (SEM), fluoresserende mikroskopie analise en aktiwiteitstoetse is na ‘n periode van sewe maande in die OAS reaktor op die MPs uitgevoer. Die SEM resultate het mikrobiese aanhegting en kolonisasie op die oppervlakte van die MPs getoon, en daar was ‘n duidelike verskil tussen partikels met geen aanhegting en partikels wat ten volle bedek was. ‘n Partikel wat ten volle bedek was het ‘n groot verskeidenheid van organismes getoon waarvan die morfologie ‘n aanduiding gegee het dat die volgende spesies teenwoordig was: metanobakterium, metanoplanus, metanosaeta, metanobrevibakterium en metanosarsiena. Die aanhegting en kolonisasie op die oppervlakte van die MPs is bevestig deur die resultate van die fluoresserende mikroskopie analise. Fluoressensie is waargeneem nadat die partikels met SYTO 9 gekleur is, ‘n kleurstof wat die nukleïensure van alle bakterieë kleur en groen fluoresseer wanneer dit aan UV radiasie blootgestel word. Die resultate het bevestig dat ‘n gemengde konsortium bakterieë aan die oppervlakte van die partikel geheg was. Aanhegting van metanogene is deur outofluoressensie bevestig; soos wat die MPs blootgestel is aan ‘n spesifieke golflengte van UV lig is ‘n blou kleur waargeneem, en dus bevestig dit die teenwoordigheid van metanogene. Aktiwiteitstoetse is uitgevoer om ondersoek in te stel of die MPs biogas asook metaangas produseer. Die produksie van biogas het plaasgevind in al die mediums, wat die teenwoordigheid van sowel asitogene as metanogene bevestig. Met die byvoeging van MPs by een van die OAS reaktors (RMP) is geen aanvanklike verskil waargeneem nie. Soos wat die OLT verhoog is tot by 6 kg CSB.m-3.d-1 en hoër het die pH en alkaliniteit van Rkontrole egter verskille begin toon. Daar was drie gevalle waar die pH en alkaliniteit van Rkontrole verlaag het en dit is nie in RMP waargeneem nie. Die ander verskil tussen RMP en Rkontrole is aan die einde van die toets waargeneem. Met die verwydering van die biomassa van beide reaktore is ‘n beduidende verskil in die grootte van die granules waargeneem, en die meeste van die biomassa in RMP was in ‘n geflokkuleerde eerder as ‘n gegranuleerde vorm. Op grond van die data van hierdie studie kan vertering by gemengde alkoholiese afloopwater wel plaasvind, maar die reaktor moet by verhoogde OLT meer deeglik gemonitor word. Hierdie studie het bevestig dat die gebruik van MPs as ‘n aanhegtingsmedium effektief is, en verder kan ook bevestig word dat die byvoeging van MPs nie die werking van die OAS reaktor affekteer nie.

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