SUNScholar - Browsing by Author "Myburgh, P. A."

Browsing by Author "Myburgh, P. A."

Now showing 1 - 10 of 10

Annual dynamics of winery wastewater volumes and quality and the impact of disposal on poorly drained duplex soils
(South African Society for Enology and Viticulture, 2018) Mulidzi, A. R.; Clarke, C. E.; Myburgh, P. A.
The composition and volume of winery wastewater change throughout the year. Quality is usually at its worst when vintage operations are dominated by the production of red wines. The objective of this study was to investigate the annual dynamics of winery wastewater volumes and quality, as well as the effect of winery wastewater irrigation on the chemical soil properties of a poorly drained duplex soil. The study was conducted over two and half years. The wastewater contained a high concentration of potassium (K+) and low levels of sodium (Na+). The results of the study confirmed that winery wastewater did not comply with South African national legislation for wastewater irrigation with regard to chemical oxygen demand (COD) and pH throughout the study period, while some prominent spikes were observed in sodium adsorption ratio (SAR) and electrical conductivity (EC). Land application of winery wastewater resulted in the accumulation of high levels of K+ in the soil. It is important to note that this study represents the worst-case scenario, i.e. large amounts of wastewater were disposed of on a small surface, particularly during harvest and in winter. Due to the high volumes of wastewater irrigation plus rainfall, the inevitable over-irrigation leached large amounts of K+ beyond 90 cm soil depth. Unfortunately, the leached elements are bound to end up in natural water resources, resulting in the pollution of the environment.
An assessment of winery wastewater diluted for irrigation of grapevines in the Breede River Valley with respect to water quality and nutrient load
(South African Society for Enology and Viticulture, 2015) Howell, C. L.; Myburgh, P. A.; Lategan, E. L.; Hoffman, J. E.
Possible re-use of winery wastewater for irrigation was investigated in a field trial with micro-sprinklerirrigated Cabernet Sauvignon/99 Richter in the Breede River Valley region of South Africa. Irrigation with winery wastewater diluted to 100, 250, 500, 1 000, 1 500, 2 000, 2 500 and 3 000 mg/L chemical oxygen demand (COD), respectively, was compared to irrigation with raw river water. Since the pH was lower than 6, the diluted wastewater could cause nutrient toxicity. The diluted winery wastewater did not pose any salinity hazard, as the electrical conductivity was well below 2 dS/m. For the given range of dilutions, the sodium adsorption ratio never exceeded 10, which indicates that the water posed no sodicity hazard. Sodium and Cl- never exceeded 115 and 150 mg/L, the respective upper thresholds for grapevines. With the exception of N, levels of H2 PO4 - , K+ , Na+ , Ca2+, Mg2+, HCO3 - , SO4 2- and B3+ in the diluted wastewater increased with a decrease in dilution level. The N load in diluted winery wastewater appeared to be completely inadequate to supply the grapevine’s requirements. In contrast, the P load in the winery wastewater diluted to 2 500 mg/L COD and higher would supply more than adequate P if the grape yield amounts to 10 t/ha. Likewise, the dilution of winery wastewater to 250 mg/L COD and higher would supply more than adequate K+ if the grape yield amounts to 10 t/ha. However, K+ applied via the wastewater will only be beneficial if it is not leached from the root zone during winter.
Design of a pot experiment to study the effect of irrigation with diluted winery wastewater on four differently textured soils
(South African Water Research Commission, 2016-01) Mulidzi, A. R.; Clarke, C. E.; Myburgh, P. A.
Due to the intensification of environmental legislation, the wine industry is expected to find solutions for the treatment or re-use of winery wastewater. The objective of the study was to design and evaluate a pot experiment for determining the effects of irrigation with diluted winery wastewater on different soils. Four pedogenetically different soils were included in the experiment, i.e., (i) alluvial sand containing 3.3% clay from Rawsonville, (ii) aeolic sand containing 0.4% clay from Lutzville, (iii) shale-derived soil containing 20% clay from Stellenbosch, and (iv) granite-derived soil containing 13% clay from Stellenbosch. The pot experiment was carried out under a rain shelter at ARC Infruitec-Nietvoorbij. Soils were packed in 3.54 dm3 PVC pots to a bulk density of 1 400 kg/m3. The four soils were irrigated using winery wastewater that was diluted to 3 000 mg/L COD. Municipal water was used to irrigate the control treatment of each soil. The relatively simple mixing and irrigation infrastructure enabled irrigation of more than one soil with diluted winery wastewater in one experiment. It was possible to irrigate the soils accurately when approx. 85% of the water had evaporated as no visual drainage occurred. Since the pot experiment could be continued under the rain shelter during winter, results were obtained quicker compared to an open field study. However, weighing the pots every second day was time consuming. Therefore, it is recommended that load cells are to be used to record daily mass losses automatically in future pot experiments.
Effect of irrigation using diluted winery wastewater on the chemical status of a sandy alluvial soil, with particular reference to potassium and sodium
(South African Society for Enology and Viticulture, 2018) Howell, C. L.; Myburgh, P. A.; Lategan, E. L.; Hoffman, J. E.
The re-use of winery wastewater for irrigation was investigated in a field trial with micro-sprinklerirrigated Cabernet Sauvignon/99 Richter in the Breede River Valley region of South Africa. Irrigation with winery wastewater diluted with river water to 100, 250, 500, 1 000, 1 500, 2 000, 2 500 and 3 000 mg/L chemical oxygen demand (COD) was compared to irrigation with river water. No trends were found in soil pH(KCl) and electrical conductivity of the saturated soil extract (ECe ) that were related to the different levels of dilution. However, ECe was considerably higher after the application of diluted winery wastewater irrigations compared to ECe at bud break. This suggests an accumulation of salts from the diluted winery wastewater. Under the prevailing conditions, soil K+ and Na+ increased with a decrease in the dilution of the winery wastewater. Increases in K+ could have a negative impact on wine colour stability should potassium be taken up by the grapevine in sufficient quantities, particularly if soil K+ accumulates to such an extent that it is luxuriously absorbed by grapevines. There were no consistent trends with regard to soil organic C, which indicates that there was too little organic material in the wastewater to have had a positive effect on soil fertility. Furthermore, organic material in the wastewater probably oxidised when the soil was aerated between irrigations. Although irrigation with diluted winery wastewater had almost no other effects, element accumulation, particularly with respect to K+ and Na+, might be more prominent in heavier soils or in regions with low winter rainfall.
Effect of irrigation using diluted winery wastewater on vitis vinifera l. cv. cabernet sauvignon in a sandy alluvial soil in the Breede River Valley – vegetative growth, yield and wine quality
(South African Society for Enology and Viticulture, 2016-09) Howell, C. L.; Myburgh, P. A.; Lategan, E. L.; Schoeman, C.; Hoffman, J. E.
The re-use of winery wastewater for irrigation was investigated in a field trial with micro-sprinklerirrigated Cabernet Sauvignon/99Richter in the Breede River Valley region of South Africa. Irrigation with winery wastewater diluted with river water to 100, 250, 500, 1 000, 1 500, 2 000, 2 500 and 3 000 mg/L chemical oxygen demand (COD) was compared to irrigation with river water. Under the prevailing conditions, plant water status did not respond to irrigation using diluted winery wastewater. Leaf and shoot element contents did not respond consistently to irrigation using diluted winery wastewater. There were no differences in vegetative growth or yield or juice characteristics, with the exception of juice pH. Consequently, water use and water status of the grapevines also were not affected. The results indicate that a summer interception crop may increase the evapotranspiration of vineyards substantially. The irrigation of grapevines using diluted winery wastewater did not have detrimental effects on wine colour and sensory wine characteristics, and the grapevines did not respond to the COD level per se. This indicates that sufficient aeration occurred between irrigations, which allowed organic carbon breakdown. The low salinity and sodicity levels in the diluted winery wastewater could be a further explanation of why the grapevines did not respond to the wastewater irrigation. In heavier soils, regions with lower winter rainfall, situations where the winery wastewater contains more potassium or where no interception crop is cultivated during summer, grapevine responses may be more pronounced.
Effect of irrigation with diluted winery wastewater on phosphorus in four differently textured soils
(South African Society for Enology and Viticulture, 2016-04) Mulidzi, A. R.; Clarke, C. E.; Myburgh, P. A.
The wine industry needs solutions for wastewater treatment, as environmental legislation for its disposal is increasingly being enforced due to non-compliance. The feasibility of re-using diluted winery wastewater was assessed in a pot experiment under a rain shelter over four simulated irrigation seasons. Four soils varying in parent material and clay content, viz. aeolic sand from Lutzville containing 0.4% clay, alluvial sand from Rawsonville containing 3.3% clay, granite-derived soil from Stellenbosch containing 13% clay, and shale-derived soil from Stellenbosch containing 20% clay, were irrigated with wastewater diluted to 3 000 mg/L COD (chemical oxygen demand), whereas the control received municipal water. Irrigation with diluted winery wastewater increased the pH(KCl) in the shale- and granite-derived soils into the optimum range for P availability. Although pH(KCl) in the aeolic sand was initially above the optimum range, relatively high Na+ levels also caused available P to increase as the pH(KCl) increased. The pH(KCl) in the alluvial sand increased beyond the optimum range, thereby causing a reduction in the available P. This indicates that irrigation with diluted winery wastewater may only enhance P absorption if the pH(KCl) shift is towards the optimum. It must be noted that the results represent a worst-case scenario, i.e. in the absence of rainfall or crops.
Implementation of a performance-grade bitumen specification in South Africa
(South African Institution of Civil Engineering, 2019-09) Bredenhann, Steph; Myburgh, P. A.; Jenkins, Kim J.; O’Connell, Johan; Rowe, Geoff; D’Angelo, John
South Africa has been experiencing higher traffic volumes and heavier loads over the past several years. This has been accompanied by an increase in premature asphalt failures. Selection of the appropriate asphalt binder is critical for improving performance. Empirical bitumen testing has increasingly failed to relate test results to pavement performance, as the traffic volume and loading have changed. Moreover, empirical tests cannot effectively characterise polymer-modified bitumens that are increasingly being used in South Africa. This changing environment calls for the establishment of specifications based on fundamental engineering properties which relate to actual pavement performance. This paper discusses the fundamental principles of the performance grade (PG) specification being introduced in South Africa. It explains how these fundamental principles create a rational framework for the specification, and present a clear set of compliance criteria to ensure the optimal selection of bituminous binders. The reasons for transitioning to a PG specification are discussed, along with the basis of the specification, rheological concepts, measurements required to characterise bituminous binders, and the simulation of ageing in relation to durability. The framework of the specification, including test procedures, provisional compliance limits and mandatory reporting of test results as an interim measure, are discussed in this paper. Finally, some test results received to date for selected typical South African binders are reported and evaluated. These results indicate that current binders being used in South Africa can easily conform to the proposed PG specification in terms of deformation requirements without any disruption to the processes of the refineries or secondary manufacturers. The fatigue properties of binders are still under evaluation and thus not included in the specification framework. Only information gathered will inform the final decision.
Response of soil chemical properties to irrigation with winery wastewater on a well-drained sandy soil
(South African Society for Enology and Viticulture, 2019) Mulidzi, A. R.; Clarke, C. E.; Myburgh, P. A.
Most wineries in South Africa dispose of their wastewater through land application. This is carried out by irrigating small areas of cultivated pasture with the wastewater or ponding, with the former being the more general practice. Land application of winery wastewater results in the accumulation of potassium (K+) and sodium (Na+) in the soil and leaching of calcium (Ca2+) and magnesium (Mg2+).This could lead to long term instability of soil structure. The objective of this study was to investigate the effect of irrigation with winery wastewater on chemical soil properties and potential environmental impacts. Therefore, an existing grazing paddock at a winery near Rawsonville was selected where wastewater had been applied for many years. Due to the high volumes of wastewater irrigation plus rainfall, the inevitable over-irrigation leached large amounts of cations, particular K+ and Na+, beyond 90 cm soil depth at the selected study site. These leached elements are likely to end up in natural water resources in the long run. Irrigation with winery wastewater did not have a pronounced effect on soil pH(KCl). This was probably due to the decomposition of organic matter, and the fact that the applied salts were leached beyond 90 cm depth. The study confirmed that disposal of winery wastewater through land application can only be recommended where wastewater application will not exceed the water requirement of the crop as well as the water holding capacity of the soil which is being irrigated.
Seasonal variation in composition of winery wastewater in the Breede River Valley with respect to classical water quality parameters
(South African Society for Enology and Viticulture, 2016-10) Howell, C. L.; Myburgh, P. A.; Lategan, E. L.; Hoffman, J. E.
The annual wastewater quality dynamics of a winery from which wastewater was sourced for a field experiment investigating the dilution of winery wastewater for vineyard irrigation were determined. Annual mean monthly pH ranged from 4.2 to 6.8 and was lower during grape harvest than in winter. Electrical conductivity (EC) increased from the start of harvest (February) and reached a maximum in May, followed by a decline to a minimum in August. The increase in EC probably originated from cleaning agents used in the winery, as well as K+ in the grape lees and spillage from the grape fermentation process. With the exception of August, EC exceeded the critical value of 0.75 dS/m, which is the salinity threshold for water used for grapevine irrigation. The mean monthly chemical oxygen demand (COD) level increased from January and was highest at peak harvest (March). The K+ and Na+ levels in the winery wastewater increased from February to May. The sodium adsorption ratio (SAR) ranged from 2.4 to 9.0 and increased from January to June. Although COD concentration in winery wastewater is the preferred indicator of water quality for the South African wine industry, it did not provide a reliable indication of suitability for irrigation. However, EC was strongly determined by the K+ concentration. This was to be expected, since K+ is usually the most abundant cation in winery wastewater. Therefore, EC would be a more reliable indicator of winery wastewater quality than COD concentration, particularly with regard to the concentrations of cations such as K+ and Na+.
Water consumption of South African vineyards : a modelling approach based on the quantified combined effects of selected viticultural, soil and meteorological parameters
(Stellenbosch : Stellenbosch University, 1998-12) Myburgh, P. A.; Van Huyssteen, L.; Archer, E.; Stellenbosch University. Faculty of AgriSciences. Department of Soil Science.
AFRIKAANSE OPSOMMING: Normaalweg word slegs een of twee stelle gewasfaktore in kombinasie met 'n verwysingwaterverbuik (ET) vir die beraming van gewas waterverbruik (ET) van wingerde gebruik. As gevolg van variasie tussen wingerde beperk hierdie gewasfaktore die akkuraatheid waarmee produsente besproeiing kan bestuur om produksie en gehalte te optimiseer. Die doel van hierdie studie was om 'n waterverbruikmodel, wat die variasie tussen wingerde in ag neem, te ontwikkel. Die hittepuls tegniek is gekalibreer om sapvloei oor kort periodes in wingerdstamme te meet. 'n Kalibrasiekurwe vir sapvloei teenoor tyd is ontwikkel. Om vir variasie van sapvloei in xileem voorsiening te maak, is vier sensors per stam gebruik. Sapvloei is in geselekteerde wingerde onder verskillende toestande gemeet. Daaglikse sapvloei per stok het toegeneem met blaaroppervlak. Uurlikse sapvloei het nie reglynig met straling toegeneem nie, wat daarop gedui het dat maksimum huidmondjie-opening net 'n vaste hoeveelheid transpirasie toegelaat het. In sommige gevalle het sapvloei gedurende die dag tydelik afgeneem wat op 'n waterbesparingsmeganisme as gevolg van huidmondjie-sluiting onder toestande van hoe ligintensiteit gedui het. In vergelyking met droëlandtoestande, het besproeiing slegs aanvanklik hoë sapvloeipieke geïnduseer. Dit het impliseer dat, benewens verhoogde transpirasie, turgiditeit in selle ook herstel is. In vergelyking met loweroppervlak-oriëntasie en meteorologiese toestande, het oeslading en besproeiing beperkte effekte op daaglikse sapvloei gehad. Tagtig persent van variasie in sapvloei kan op grand van blaaroppervlak en ET voorspel word. As gevolg van verskille in die hoeveelheid blare aan straling blootgestel, was die voorspelling meer akkuraat wanneer tussen horisontale en vertikale lowers onderskei is. Aangesien toename in beskaduwing met 'n toename in lowerdigtheid, asook kultivareienskappe en waterspanning, nie in ag geneem is nie, word hierdie modelle as 'n eerste benadering beskou. 'n Li-Cor LAl -2000 Plant Canopy Analyzer (PCA) is in geselekteerde wingerde gekalibreer om blaaroppervlakindeks (BOIpca) te meet. Alhoewel die PCA werklike blaaroppervlakindeks (BOI) onderskat het, is die nou korrelasie tussen BOl pca en BOI gebruik om blaaroppervlakontwikkeling te meet. Blaaroppervlakontwikkeling is in agt wingerde, wat ten opsigte van kultivar, plantafstand en prieelstelsel verskil het, in vyf wingerdbougebiede gemeet. Seisoenale verandering in blaaroppervlak kon met derde orde polinomiese vergelykings, met dag van groeiseisoen as enigste veranderlike, voorspel word. Afsonderlike potensiële groeikurwes is vir die Winterreën en Somerreën gebiede ontwikkel. Die gebruik van lootmassa om maksimum blaaroppervlak te voorspel, was minder akkuraat as wanneer die vars blaarmassa gebruik is. Horisontale priële het meer blare per eenheid lootmassa as vertikale priële geproduseer. Water wat daagliks in bogrondse dele van die wingerdstok gestoor word, het slegs breukdele van 'n millimeter beloop en kon dus in die voorspelling van waterverbruik geïgnoreer word. Verdamping vanaf die grondoppervlak (E) is met mini-lisimeters in wingerde gemeet om die Boesten & Stroosnijder model te evalueer en aan te pas. Onder nat grondtoestande was daar 'n neiging tot hoër E in die middelste gedeelte van die werksry. Verdamping vanaf onbewerkte grond sonder 'n deklaag is met aanvaarbare akkuraatheid deur die model voorspel. Die model moes egter aangepas word om interaksie tussen die lower en grond in ag te neem. Daar was 'n neiging tot hoër E onder horisontale priële as by vertikale priële gedurende fase twee van verdamping. Verdamping het ook tussen die ses grondtipes wat in hierdie studie gebruik is, verskil. 'n Strooideklaag het E betekenisvol onder relatiewe nat toestande beperk. Vir die meeste gronde het die deklaag na tien dae geen verskil in vergelyking met grond sonder 'n deklaag gehad nie. Daar was 'n reglynige verband tussen kumulatiewe E en ET vasgestel. Kumulatiewe E was gemiddeld ongeveer 30 % van kumulatiewe ET. Die transpirasie en oppervlakverdamping modelle is gekombineer om as basis vir 'n voorlopige voorspellingsmodel vir evapotranspirasie te dien. Gesimuleerde ET is teenoor werklike ET, soos gemeet in agt wingerde onder verkillende toestande, vergelyk. Hierdie wingerde het 'n reeks veranderlikes soos besproeiingstelsel, grondtipe, grondwateronttrekkingspeile, prieelstelsel en groeikrag aangespreek. Slegs eenvoudige parameters soos lootmassa, plantafstand, loweroppervlak-orientasie, verwysingswaterverbruik en 'n konstante waarde wat die verdampingsverliese vanaf 'n spesifieke grondtipe bepaal, is as invoere gebruik. Gesimuleerde ET het bevredigend met werklike ET vergelyk, en dus die akkuraatheid van die model bevestig.

Browsing by Author "Myburgh, P. A."

Results Per Page

Sort Options