Investigating wastewater generation and wastewater effluent treatment in the South African fruit & vegetable processing industry

Thesis (MScFoodSc)--Stellenbosch University, 2021.

ENGLISH ABSTRACT: During the mid-1980s, a series of national surveys was conducted by the Water Research Commission (WRC). These surveys (also known as NATSURV reports) investigated water and wastewater management within the industrial environment of South Africa. These original NATSURVs have, however, become outdated. The WRC has, therefore, commissioned updates for these reports. The aim of this study is to gather relevant information, pertaining to water and wastewater management in the fruit and vegetable processing industry, by means of a national survey. The quality and scope of the knowledge acquired should be suitable to be included in the second edition NATSURV 19 (Water and Wastewater Management in the Fruit and Vegetable Processing Industry). As a means of comparison, an in-depth literature review was conducted before commencing with the surveying process. The literature review focussed on the various production processes found in the fruit and vegetable processing industry. Another key component of the literature review was detailing the various wastewater treatment methods available to the fruit and vegetable processing industry. An industry database was built using a combination of internet sources, industry databases and referrals. Thereafter, all 78 facilities included in the database were telephonically contacted in order to verify their operational status. An internet-based survey was then made available to persons with executive authority within each facility. Site-visits of selected facilities were being conducted simultaneously. Each site visit included an interview with a person possessing in-depth knowledge of the processes involved. A walk-through audit of the facility was also conducted during these site- visits. The data acquired from the internet-based questionnaire and site-visits was subjected to Qualitative Data Analysis (QDA) using the ATLAS.ti 9 analytic software. Furthermore, water consumption, effluent generation and effluent quality parameters were also critically evaluated and compared to the available literature. After analysis was completed it was found that some facilities reported SWI figures which were similar or better than their international counterparts. Furthermore, when considering the SWI determined for certain products in the 1987 NATSURV, it appears that some facilities were able to report improved SWI figures. This indicates at least anecdotally that the water-use efficiency of the South African FVPI has improved over the last 30 years. Analysis further revealed that raw material washing and facility cleaning were the most water intensive processes. The QDA revealed that the majority of facilities investigated do not utilise advanced wastewater treatment techniques. This may be due to lengthy pay-back period often associated with capital investments of this nature. Effluent disposal routes are largely influence by the nature of a facility’s surroundings. Rural facilities often choose to irrigate their effluents, whilst facilities in an urban environment preferred to discharge directly into the municipal wastewater systems. It was found that in addition to environmental concerns, financial incentives are often the reason for the improvement of water consumption and wastewater treatment within the South African FVPI. This study’s aim to provide suitable information and recommendations, to be included in the updated NATSURV 19, was achieved. Furthermore, this study has provided a sufficient sample of water and wastewater management practices observed in the industry, future research should, therefore, focus on individual facilities or processes and the optimisation thereof.

AFRIKAANSE OPSOMMING: Die Waternavorsingskommissie (WNK) het vanaf die laat 1980s ‘n reeks nasionale opnames uitgevoer. Hierdie opnames (bekend as die NATSURV verslae) het die bestuur van water en afvalwater in die Suid-Afrikaanse industriële omgewing ondersoek. Hierdie verslae is egter al verouderd en daarom het die WNK aangekondig dat hierdie verslae opdateer sal word. Die doel van hierdie ondersoek is dus om relevante inligting aangaande water- en afvalwaterbestuur in die vrugte- en groentverwerkingsbedryf (FVPI) in te samel, deur van ‘n nasionale opname gebruik te maak. Die kwaliteit en omvang van hierdie inligting moet sodanig wees dat dit deel kan vorm van die tweede uitgawe van die NATSURV 19 verslag (Water- en afvalwaterbestuur in die groente- en vrugteverwerkingsbedryf). Voordat die opname kon begin, was ‘n gedetailleerde literatuurstudie gedoen sodat daar vergelykings getref kon word. Die literatuurstudie het klem gelê op die verkeie produksie-prosesse wat in die vrugte- en groenteverwerkings bedryf waargeneem word. ‘n Ander belangrike komponent was om die verskeie afvalwaterbehandelingsmetodes wat aan die vrugte- en groenteverwerkingsbedryf beskikbaar is, noukerig te dokumenteer. ‘n Bedryfsdatabasis is gebou met die hulp van internetnavorsing, verwysings as ook die verskillende bedryfsdatabasisse in die industrie. Daarna is al 78 fasiliteite telefonies gekontak om hul operasionele status te verifieer. ‘n Internet-gebaseerde opname is daarna beskikbaar gemaak aan persone met die nodige kennis, binne elke fasiliteit. Besoeke aan geselekteerde fasiliete was ook gedoen. Gedurende elke besoek was ‘n onderhoud gevoer met ‘n persoon wat oor die nodige kennis rakende die toegepaste prosesse beskik. Elke besoek het ook ‘n in diepte analise van die terrein behels. Die data wat via internet opnames en besoeke aan die fasiliteite verkry is, was onderworpe aan kwalitatiewe data-analise (QDA) deur gebruik te maak van die ATLAS.ti 9- ontledingsplatvorm. ‘n Kritiese evaluasie van die fasiliteite se waterverbruik, afvalwater generasie en afvalwaterkwaliteit was ook uitgevoer. Hierdie data parameters was daarna vergelyk met beskikbare literatuur. Na ontleding skyn dit te blyk dat sommige van die fasiliteite SWI-syfers toon wat soortgelyk of selfs beter is as dié van hul internasionale eweknieë. Sommige fasiliteite toon ook beter spesifieke waterinnames (SWI’s) in verhouding met diéwat in die oorspronklike NATSURV vir soortgelyke produkte ingestel is. Dit dui anekdoties ‘n verbetering in die waterverbruiksdoeltreffendheid gedurende die afgelope dertig jaar aan. Na verdere ontleding was daar gevind dat die skoonmaak van rou materiale en die fasiliteite self, die grootste verbruikers van water was. QDA het aan die lig gebring dat meeste fasiliteite nie van gevorderde afvalwaterbehandeling tegnieke gebruik maak nie. ‘n Moontlike rede hiervoor kan die lang terugbetalingstydperk van die kapitaalbelegging wees. Die afvalwater verwyderings roetes word grootendeels deur die fasiliteit se onmiddelike omgewing bepaal. Fasiliteite in landelike omgewings gebruik gereeld hul afvalwater vir besproeingsdoeleindes, terwyl fasiliteite in ontwikkelde omgewings gewoonlik kies om hul afvalwater na munisipale afvalwaterstelsels te stort. Daar is egter gevind die verbetering van waterverbruik en afvalwaterbehandeling binne die Suid-Afrikaanse FVPI nie net gemotiveer word deur omgewingsbewustheid nie, maar ook deur finansiële implikasies. Die doel om inligting en aanbevelings te lewer wat geskik is om by die opgedateerde NATSURV ingesluit te word is deur hierdie studie bereik. Daar is lig gewerp oor die huidige water- en afvalwaterbestuurspraktyke in die vrugte- en groenteverwerkingsbedryf, en daarom moet toekomstige navorsingsprojekte fokus op die individuele fasiliteite asook die optimalisering van prosesse binne hierdie fasiliteite.

Masters