A high rate biofilm contact reactor for winery wastewater treatment

De Beer, Danielle Marguerite (2016-12)

Thesis (PhD)--Stellenbosch University, 2016.

Thesis

ENGLISH ABSTRACT: Winemaking produces variable volumes wastewater rich in biodegradable organic material, with fluctuating chemical composition and pH values according to the seasonal activities of the cellar. Releasing untreated winery wastewater into the environment can cause eutrophication and toxicity in surface water and has detrimental effects on soil condition and ground water quality. Rising costs of effluent disposal, limited availability of freshwater resources and increasingly stringent water use regulations imposed on wineries are enthusing interest in low cost, sustainable, and robust wastewater treatment solutions for wineries. The objective of this study was to design, construct and implement an easily pre-assembled, energy efficient pilot scale biofilm reactor with a small footprint for winery wastewater treatment. A commercial cooling tower as a trickling filter reactor unit was central to the design. The system was tested at a winery in Stellenbosch and after proving to be effective, was up-scaled by adding a second cooling tower to the system as a secondary reactor, treating the effluent from the first subunit, contributing to the overall waste removal efficiency of the system. The double-unit pilot system was tested in six trials over three years. The system showed effective, robust treatment of winery wastewater of varying strengths with minimal solid waste production, consistently reducing chemical oxygen demand (COD) (average 93% reduction), total nitrogen, sulfate, phosphate and suspended solids (average 90% reduction) to meet prescribed regulations for irrigation. The system performed at its peak when treating highly concentrated wastewater during harvest season. The pH of treated wastewater was consistently buffered from highly acidic and basic values to close to neutral. To understand how the biofilm worked to remove contaminants within the system, and how the additional cooling tower unit expanded the treatment scope of the system, a three-tiered investigation of the microbial community structure, distribution of microorganisms and collective metabolic capabilities of biofilm samples from each cooling tower subunit was investigated. Next generation sequencing revealed that the biofilm populations of the two reactor subunits were phylogenetically distinct, with only 12% of operational taxonomic units (OTUs) overlapping between the two biofilms. Taxonomic data indicated that carbohydrate reducing bacteria dominated the population of the first cooling tower, while nitrifying and denitrifying bacteria dominated the second. Fluorescent in situ hybridization coupled with confocal laser scanning microscopy (FISH-CLSM) revealed the stratified distribution of aerobic Gammaproteobacteria across the depth of the biofilm from the first cooling tower unit, and showed distinct distribution patterns of Nitrosomonas and Nitrospirae in biofilm samples from the first and second cooling tower units. Substrate utilization analyses using the Biolog system revealed that the majority of the carbon substrates that were tested were utilized in the biofilm samples from both cooling towers, but that important metabolic utilization capabilities fell exclusively either within the consortium of the biofilm from tower 1 or tower 2. Collectively, the data from each of the three analytical approaches indicated that by adding a second subunit to the bioreactor, the treatment capacity of the system was not merely expanded, but that the second reactor subunit added to the microbial and metabolic diversity of the system.

AFRIKAANS OPSOMMING: Die wynmaakproses produseer veranderlike volumes afvalwater wat ryk is aan bioafbreekbare organiese materiaal, met wisselende chemiese samestelling en pHwaardes volgens seisoenale aktiwiteite van die kelder. Die vrystelling van onbehandelde kelderafvalwater in die omgewing kan nadelige voedingstofverryking en toksisiteit in oppervlakwater veroorsaak en kan die grondsamestelling en grondwatergehalte negatief beïnvloed. Stygende kostes van uitvloeiselbeskikking, beperkte beskikbaarheid van varswaterbronne en toenemend strenger regulasies met betrekking tot waterverbruik by wynkelders kweek belangstelling in lae koste, volhoubare en robuuste afvalwateroplossings vir wynkelders. Hierdie studie was daarop gemik om 'n biofilmreaktor vir kelderafvalwaterbehandeling op proefskaal te ontwerp, bou en implementeer wat maklik voor installasie in 'n fabriek saamgestel kan word, wat op 'n energie-doeltreffende en volhoubare wyse werk en 'n kompakte ontwerp beslaan. Die basiese ontwerp was 'n sypelfilterreaktoreenheid bestaande uit ’n kommersiële koeltoring. Die stelsel is getoets by 'n kelder in Stellenbosch, en nadat die stelsel se doeltreffendheid bewys is, is dit opgeskaleer deur 'n tweede koeltoring as sekondêre reaktor by te voeg. Die behandelde uitvloeisel van die eerste koeltoringsubeenheid is derhalwe in die tweede koeltoringeenheid behandel, wat die doeltreffendheid van die stelsel as geheel uitgebrei het. Die dubbeleenheidproefreaktorstelsel is in ses afsonderlike toetse oor drie jaar getoets. Die stelsel het kelderafvalwater doeltreffend behandel met minimale vaste afvalproduksie. Die stelsel het kontaminante in die afvalwater konsekwent verminder. Chemiese suurstofbehoefte (COD) is gemiddeld met 93% verminder, stikstof, sulfate en fosfate het afgeneem en vaste stowwe in suspensie het met gemiddeld 90% afgeneem; trouens, die behandelde water se gehalte het binne die voorgeskrewe besproeiingsregulasies geval. Die stelsel was op sy doeltreffendste tydens die behandeling van hoogs gekonsentreerde afvalwater tydens oestyd. Die pH van behandelde afvalwater is deurgaans gebuffer van baie suur en basiese waardes na naastenby neutraal. Ten einde die biofilm se verwydering van besoedeling te verstaan en hoe die bykomende koeltoringeenheid die stelsel se behandelingsomvang uitbrei, is 'n drieledige ondersoek van stapel gestuur om die mikrobiese gemeenskapstruktuur, die verspreiding van mikro-organismes en kollektiewe metaboliese vermoëns van biofilmmonsters van elke koeltoringeenheid te ondersoek. Nuutste generasie volgordebepaling het gewys dat die biofilmbevolkings van die twee koeltoringsubeenhede filogeneties verskil, met slegs 12% oorvleueling van operasionele taksonomiese eenhede tussen die twee biofilms. Volgens taksonomiese data het koolhidraat-metaboliserende bakterieë die bevolking van die eerste koeltoring oorheers, terwyl nitrifiserende en denitrifiserende bakterieë die gemeenskap van die tweede toring oorheers het. Fluoresserende in situ-hibridisasie met konfokaleskandeerderlasermikroskopie het gestratifiseerde verspreiding van aërobiese Gammaproteobacteria regoor die diepte van die biofilm van die eerste koeltoringeenheid geopenbaar, en het die verskillende verspreidingspatrone van Nitrosomonas en Nitrospirae in die biofilmmonsters van die eerste en tweede koeltoringeenhede uitgewys. Biolog-substraatbenuttingsontledings het getoon dat die meerderheid getoetste koolstofsubstrate deur die biofilmmonsters van beide koeltorings verbruik is, maar dat belangrike metaboliese benuttingsvermoëns uitsluitlik óf binne die konsortium van die biofilm uit toring 1 óf toring 2 geval het. Gesamentlik het die data van elk van die drie analitiese benaderings aangedui dat die toevoeging van 'n tweede koeltoringeenheid by die bioreaktor die stelsel se behandelingskapasiteit uitgebrei het, en dat die tweede subeenheid bydra tot die mikrobiese en metaboliese diversiteit van die stelsel en die uitbreiding van die behandelingsomvang van die stelsel as geheel.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/100031
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