This study describes the variation of an important greenhouse gas, nitrous oxide (N2O) at site-specific from the bio-lines unit at Wastewater Treatment Plant (WWTP) in Halmstad. The sampling campaign at the WWTP was carried out for three consecutive days during the weekdays in March 2021 with total of 144 samples were taken in GHG sample vials (exetainers) and analysed for N2O measurements using gas chromatography. Other nitrogen parameters data (NO2-N, NO3-N, and total nitrogen) were also collected. Using statistical analysis, comparisons were focused on a year period (March 2020 and 2021). This study found that N2O concentration generated in March 2021 was significantly lower than March 2020. Results also showed significant differences of N2O concentration between the three different zones (anaerobic, anoxic, and aerobic) among the bio-lines, where the highest N2O concentration was only found in aerobic zones. Correlation analysis showed only total nitrogen is negatively correlated with N2O-N in the aerobic zones. These findings will enable better understanding of processes along the bio-lines as a step for WWTP operators to improve N2O monitoring.

Photocatalysis is an advanced oxidation process for the purification and remediation of contaminated waters and wastewaters, and is advantageous over conventional treatment technologies due to its ability to degrade emerging and recalcitrant pollutants. In addition, photocatalytic disinfection is less chemical-intensive than other methods such as chlorination, and can inactivate even highly resistant microorganisms with good efficacy. Process sustainability and cost-effectiveness may be improved by utilizing solar irradiation as the source of necessary photons for photocatalyst excitation. However, solar-induced activity of the traditionally-used titania is poor due to its inefficient visible light absorption, and recombination of photo-excited species is problematic. Additionally, mass transfer limitations and difficulties separating the catalyst from the post-treatment slurry hinder conversions and efficiencies obtainable in practice. In this research, various strategies were explored to address these issues using novel visible light active photocatalysts. Two classes of carbon-enhanced photocatalytic materials were studied: activated carbon adsorbent photocatalyst composites, and carbon-doped TiO2. Adsorbent photocatalyst composites based on activated carbon and plasmonic silver/silver chloride structures were synthesized, characterized, and experimentally investigated for their photocatalytic activity towards the degradation of model organic pollutants (methyl orange dye, phenol) and the inactivation of a model microorganism (Escherichia coli K-12) under visible light. The adsorptive behaviour of the composites towards methyl orange dye was also studied and described according to appropriate models. Photocatalytic bacterial inactivation induced by the prepared composites was investigated, and the inactivation mechanisms and roles of incorporated antimicrobial silver on disinfection were probed and discussed. These composites were extended towards magnetic removal strategies for post-use separation through the incorporation of magnetic nanoparticles to prepare Ag/AgCl-magnetic activated carbon composites, and the effect of nanoparticles addition on the properties and photoactivities of the resulting materials was explored. Another silver/silver halide adsorbent photocatalyst composite based on activated carbon and Ag/AgBr exhibiting visible light absorption due to both localized surface plasmon resonance and optical band gap absorption was synthesized and its photocatalytic activity towards organics degradation and microbial inactivation was studied. Carbon-doped mixed-phase titania was also prepared and experimentally investigated.

Forward osmosis (FO) as a novel membrane separation technology has recently been investigated in various water treatment applications. The natural mass transfer process between two solutions driven by the osmotic pressure difference leads to many operational advantages in the FO process, such as low energy consumption and minimal fouling problems. It makes FO a feasible technology for the treatment of produced water (PW). Although previously, the treatment of PW using FO has been investigated, osmotic backwashing (OB) is not systematically examined for water flux recovery of the PW fouled FO membranes. Moreover, the cleaning of FO membranes used for the simultaneous treatment of different PW streams was never previously attempted. In this study, OB was thoroughly investigated for the cleaning of PW-fouled FO membranes. Also, FO membrane chemical cleaning using SDS and NaOH solutions was examined too. To investigate OB, the cleaning efficiency of a 60 min OB cleaning protocol was examined under different FO operating modes in (5 x 20 h) experiments using synthetic desalter effluent as FO feed solution (FS) and 1.2 M NaCl solution or water-oil separator outlet (WO) as draw solutions (DS). The AL-FS (active layer facing FS) mode outcompeted the AL-DS (active layer facing DS) mode, achieving a flux of 12.9 LMH and 80.1% water reclamation when using WO as a DS. Therefore, this FO configuration 5 was selected when evaluating the cleaning protocols. Moreover, after evaluating different OB methods, the 30 min OB protocol achieved the highest system efficiency rate of 95% and was studied for the treatment of real PW streams. The SDS and NaOH chemical cleaning methods achieved flux recovery rates of 99% and 98% by the end of the third treatment cycle, respectively, outperforming the 89% flux recovery rate of the optimized OB protocol. Although the investigated cleaning methods were able to restore the system performance, a substantial increase in RSF was observed due to mainly irreversible colloidal fouling. This study demonstrates the feasibility of OB and chemical cleaning in restoring FO system performance for the simultaneous treatment of PW streams

In the Himmerfjärden Bay a large excess of nitrogen over phosphorus in the discharge from a large sewage treatment plant (STP) has suppressed growth of diazotrophic cyanobacteria in its inner parts. Implementation of nitrogen removal in the STP in 1997 drastically reduced nitrogen load and triggered growth of diazotrophs, mainly Aphanizomenon sp. This study is part of a long-term series of experiments with the overall aim to test how algal biomass and production in a receiving area can be reduced, without stimulating nitrogen fixation and biomass growth by diazotrophic cyanobacteria. Nitrogen removal was discontinued in the STP during two years (2007-8) and resumed in 2009, and the discharge shifted from 25 to 10 m depth, above the seasonal pycnocline. Cellular 15N showed that N2 was the most important N source for diazotrophic cyanobacteria, and that uptake of combined nitrogen was insignificant. As biomass was declining and at the end of the productive season, we could detect a small, but significant, increase in cellular δ15N at the inner bay stations (H3 and H4). However, this coincided with an increased proportion of Anabaena spp. of the total diazotrophic biomass. This may indicate that Anabaena spp. has a higher uptake of combined nitrogen compared with Aphanizomenon sp. or that declining populations of Aphanizomenon sp. take up combined nitrogen. We also found no evidence of uptake of combined nitrogen during the winter months when nitrogen supply is ample and Aphanizomenon sp. is devoid of heterocysts. During the first half of summer (week 21-27) heterocyst frequencies were higher at the outer stations B1 and H2, compared to the inner bay stations (H4 and H5). The lower frequencies at the inner bay stations are likely due to the reduced growth rate suffered by the Aphanizomenon sp. due to stronger competition for phosphorus by non-diazotrophs at these stations and hence lower need for heterocysts. Towards the end of summer conditions even out along the bay, as the surplus phosphorus from the spring bloom is used up at the outer stations and no heterocyst gradient is present. Heterocyst frequency varied significantly over the summer, with minimum values in the beginning of July, coinciding with the highest water temperatures, and higher frequencies in early and late summer. We suggest this is primarily due to a more efficiently functioning nitrogenase enzyme at high temperatures with a reduced need for “expensive” heterocysts. Spring heterocyst differentiation occurred around 4-6 weeks after depletion of dissolved inorganic nitrogen (DIN) and only when water temperature was 5-9 oC and a pycnocline established. It seems that temperature and light in concert will initiate growth, leading to an internal nitrogen deficiency which starts heterocyst differentiation. / Himmerfjärden eutrophication study

Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2016. / The release of wastewater to the aquatic environment is most likely to introduce some trace levels of organic contaminants, some of which may be toxic, carcinogenic, or endocrine disruptors, as well as, persistent in the environment. Additionally, increasing contamination of surface waters by wastewater effluents has made water treatment processes more challenging and expensive. The presence of these pollutants in the receiving water body may have negative effects on aquatic species and often pose potential human health risks through the reuse of treated wastewater for drinking purposes and other household use. In countries like South Africa, Namibia, USA, Singapore and Australia, water agencies are intensifying wastewater reclamation/wastewater reuse as part of their water resource agenda: in order to meet the demands of the growing populations. Nowadays, water reuse is generally considered as a viable method of water supply management. This study focused on the identification of the occurrence, quantification of emerging contaminants and evaluation of removal efficiency in wastewater treatment processes of three classes of emerging contaminants (ECs) in wastewater: 1) six types of perfluorinated compounds (PFCs), namely; perfluorooctanoic acid (PFOA), Perfluorooctane sulphonate (PFOS), perfluoroheptanoic acid (PFHpA), perfluorononanoic acid (PFNA), perfluorodecanoic acid (PFDA), and perfluoroundecanoic acid (PFUDA); 2) bisphenol A (BPA); and 3) Acetaminophen (ACP). These contaminants were identified and quantified in four wastewater treatment plants in the Western Cape. These treatment plants include three WWTPs in Cape Town, namely: Bellville WWTP, Scottsdene WWTP and Zandvliet WWTP and one WWTP in the central Karoo (Beaufort West wastewater reclamation plant).

Omkring 1970 byggdes och renoverades många vattenverk i Sverige. Dessa beräknadesdå att ha en livslängd på mellan 50-60 år, vilket i de flesta fall nu har passerat.Det har hittills saknats enhetlig information gällande hur renovering av enbassängkonstruktion i ett vattenverk bäst går till. Detta motiverade tillkomsten av följandearbete. Syftet är att undersöka vilka renoveringsmetoder som finns samt sammanställaoch utvärdera dessa. Målet är att presentera vilka riktlinjer som bör följas vid renoveraringav betongkonstruktioner i vattenverk.Arbetet ger svar på vilka skador som är vanliga i vattenverk och vad de beror på, vilkarenoveringsmetoder som är bäst lämpade, vilka material som kan användas samt vilkakrav som ställs på slutresultatet.Litteratur som behandlar betongrenovering har tjänat som utgångsmaterial. Intervjuer harskett med betongexperter, vattenverkspersonal och entreprenörer som utför denna typ avarbete.Problem i vattenverk är främst sprickor, urlakning, mekanisk erosion, korrosionsskador,kemiskt angrepp, biologisk nedbrytning och frostskador. Dessa skador renoveraslämpligen genom att ta bort den skadade betongen och ersätter den med ny, utifrån denexponeringsklass som gäller för det aktuella objektet.Borttagning av den dåliga betongen ska mot slutet göras med försiktighet för att undvikafickor vid armering och mikrosprickor i kvarvarande betong. För att få ett bra resultatkrävs både uppruggning av ytan som ska pågjutas samt fukthärdning efteråt. Vatten är ettlivsmedel så det ställs hårda renhetskrav på arbetare och maskiner samt krav på att allaprodukter som används är livsmedelsgodkända.Den slutsats som dras är att det idag inte finns någon generell och exaktrenoveringsmetod för betongkonstruktioner i vattenverk. Många olika faktorer spelar in.Det skulle dock fylla en kunskapslucka och underlätta framtida renoveringar omvattenverken gjorde en gemensam sammanställning av sina erfarenheter och lärdomar.Likaså är det ett stort värde att utbilda sin personal. / Around 1970 many water treatment plants were built and renovated in Sweden. Thesewas calculated to have a service life of between 50-60 years, which in most cases nowhave passed.The aim is to investigate which renovation methods exist and compile and evaluate these.The goal is to present which guidelines should be followed when renovating concretestructures in water treatment plants.The work gives answers to what damage is common in water treatment plants and whatthey depend on, which renovation methods are best suited, which materials can be usedand which requirements are set on the result.Problems in water treatment plants are mainly cracks, leaching, mechanical erosion,corrosion damage, chemical attack, biodegradation and frost damage. These damages arepreferably renovated by removing the damaged concrete and replacing it with new, basedon the exposure class that applies to the object in question.The conclusion is that today there is no general and exact renovation method for concretestructures in water treatment plants. Many different factors are involved.However, it would fill a gap of knowledge and facilitate future renovations if the watertreatment plants made a joint compilation of their experiences and lessons learned. It isalso a great value to educate the personnel.

Du fait de sa consommation en plein essor et d’une élimination partielle par les procédés conventionnels de traitement des eaux, l'ibuprofène, un médicament anti-inflammatoire non stéroïdien, a été détecté dans les ressources en eau, suscitant de plus en plus d'inquiétude quant à son impact possible sur l'environnement et la santé. Par ailleurs, les procédés d'oxydation avancée (POA), parmi lesquels la réaction Fenton, ont montré d’excellents résultats pour l'élimination de divers composés organiques. Traditionnellement basé sur l'utilisation du peroxyde d'hydrogène et des ions ferreux en solution, l'application à grande échelle de ce POA est encore limitée par une fenêtre de pH étroite (2 à 4) et une récupération difficile du catalyseur à base de fer. Ce travail a étudié l'oxydation Fenton de l'ibuprofène et l'activation de la réaction par irradiation ultrasonore (US) et rayonnement ultraviolet/visible (UV/Vis) et de manière à abaisser la concentration de fer dissous ou à améliorer l'activité de catalyseurs hétérogènes. A cet effet, on a d'abord évalué l'efficacité des POA individuels homogènes (sonolyse, photolyse, sono- et photo-oxydation avec H2O2, oxydation Fenton), en fonction de paramètres opératoires tels que la longueur d'onde lumineuse et la fréquence ultrasonore. Ensuite, on a examiné leurs combinaisons deux-par-deux et globale (sonophotolyse, oxydation sono-, photo- et sono-photo- Fenton) en mettant l'accent sur l'identification d'effets synergiques. En particulier, les oxydations US/Fenton et Vis/Fenton se sont révélées plus efficaces que la somme des procédés individuels grâce à la sono- et photo-régénération des ions ferreux. Ces résultats ont également servi de référence pour l'évaluation des systèmes hétérogènes. Parmi les solides testés, on a montré qu’une zéolite dopée au fer (de type Fe/ZSM5) était un catalyseur prometteur pour l'oxydation de l'ibuprofène par le peroxyde, en raison d'une efficacité élevée à pH naturel et d’une faible lixiviation du fer. Cependant, dans ce cas, on n’a observé au mieux qu'une addition d’effets des ultrasons ou de la lumière et de l'oxydation Fenton hétérogène. Outre la conversion du polluant et du carbone organique total (COT), la formation des principaux produits de dégradation a été suivie pour différents procédés et des voies possibles de dégradation ont été proposées. L’effet matrice a également été examiné en utilisant un effluent de station, qui a eu pour conséquence de réduire la performance de tous les procédés d'oxydation, en raison d'un pH tampon alcalin ou de l’atténuation de la lumière. / Due to booming consumption and only partial removal by conventional water treatment processes, ibuprofen, a non-steroidal anti-inflammatory drug, has been detected in water resources, raising increasing concerns for possible environmental and health impact. On the other hand, advanced oxidation processes (AOPs), among which Fenton reaction, have shown successful results forremoval of various organic compounds. Traditionally based on the use of hydrogen peroxide and ferrous ions in solution, large-scale application of this AOP is still limited by narrow pH window (2 to 4) and uneasy recovery of iron catalyst. This work investigated Fenton-based oxidation of ibuprofen, and reaction activation by ultrasound (US) irradiation and ultraviolet/visible light (UV/Vis) so as to lower the required concentration of dissolved iron catalyst or improve the activity of heterogeneous counterparts. To that purpose, the efficacy of individual homogeneous AOPs (sonolysis, photolysis, ultrasound/H2O2, light/H2O2, Fenton oxidation) was evaluated first, varying operating parameters such as light wavelength and ultrasound frequency. Then, their two-by-two and overall combinations (sonophotolysis, sono-Fenton, photo-Fenton and sono-photo-Fenton oxidation) were examined with emphasis on the identification of synergistic effects. In particular, combined US/Fenton and Vis/Fenton oxidation were found more effective than the sum of individualprocesses due to sono- and photo-regeneration of ferrous ions. These results also served as a reference for the assessment of heterogeneous systems. Among tested solids, iron-containing zeolite (Fe-ZSM5 type) was shown to be a promising catalyst for peroxide oxidation of ibuprofen due to high efficiency at natural pH and low iron leaching. However, in this case, no more than additive effects was observed between ultrasound/light irradiation and heterogeneous Fenton oxidation. Beside pollutant and Total Organic Carbon conversion, main degradation products were monitored for different processes and some plausible degradation pathways were proposed. Water matrix impact was also addressed using wastewater plant effluent, which resulted into hindered performance of all oxidation processes either due to alkaline buffer or light attenuation effect.

In this research, a household water treatment system was built and evaluated as a trial for improving the drinking water quality of the Nile River for the low-income communities. The system consisted of household-scale slow sand filters, and transparent polyethylene terephthalate-bottles for solar disinfection. The evaluation of the system depended on the removal/inactivation of some surrogates for the reference pathogens, and turbidity. The reference pathogens are pathogens specified by the World Health Organization to evaluate the efficiency of the household water treatment options. They were chosen to represent the classes of pathogens in water (bacteria, viruses, protozoa). The surrogates used in the evaluation of the system are Escherichia coli (E.coli), Clostridium perfringens and Escherichia coli bacteriophage (MS2). The candidate surrogates are also specified by the World Health Organization. The designed household-scale slow sand filter was very efficient in removing the different turbidity levels to ≤0.4NTU. The evaluated system is classified as highly protective because it was able to achieve higher than 4 log removal for E.coli and Clostridium perfringens, and higher than 5 log removal for MS2.

Kenaf (Hibiscus cannabinus L.) is a highly productive crop that is cultivated worldwide for its fibre content which may be used to produce various commodities. The kenaf crop was commercially cultivated in South Africa in the 1950’s, but production was discontinued from the 1960’s up to the mid 2000’s. Production commenced again and kenaf emreged as a “new” fibre crop with the first kenaf processing factory in the country going into production in 2006 in KwaZulu-Natal. Due to the importance of kenaf in manufacturing of various commodities, there was a need to investigate the agronomic practices thereof to ensure sustainable yield. Therefore a two year study (2008/09 and 2009/10 summers) was conducted in Pretoria to investigate the influence of nitrogen, plant population, row spacing and water treatments on kenaf growth, yield, chemical quality and microscopic analysis of the fibre. In total, four field trials were conducted at the Hatfield Experimental Farm of the University of Pretoria. In 2008/09 a trial was conducted to investigate effects of plant population (200,000; 300,000 and 400,000 plants ha-1), nitrogen level (0, 50, 100 and 150 kg ha-1) and row spacing (0.17, 0.34 and 0.50 m) under rainfed conditions. Sampling for growth parameters were done at 85, 113 and 126 days after planting (DAP). The biomass and chemical analysis of bark fibre were conducted only at or after the final harvest, at 126 DAP. In general, no clear effect of different treatment was observed on either parameter studied. During 2009/10 three experiments were conducted. The first two had the same nitrogen levels as in the previous season, but were grown either under rainfed or irrigated conditions. The nitrogen was applied as two dressings of 0 and 50 kg ha-1 at planting and 0, 50 and 100 kg ha-1 at thinning (35 DAP). The third experiment investigated combinations of plant population (main plots) and row spacing (sub plots) under rainfed conditions. Due to increasing stem yield with increasing plant population during 2008/09, the lowest population of 200,000 plants ha-1 was left out and 500,000 and 600,000 plants ha-1 were added. The same three row spacings as in 2008/09 were used. Nitrogen was applied at 150 kg ha-1, with 50 kg ha-1 at planting and 100 kg ha-1 at thinning. Growth and biomass parameters, water use efficiency (WUE) (nitrogen trial only) were subsequently measured up to the end of the growth cycle. The chemical characteristics of bark fibre and nutrient removal (nitrogen trial only), nutrient use efficiency as well as the nitrogen contents of leaves and stems were determined only once at final harvest. The number of fibre rings and fibre bundles were assessed only once during the growth cycle. Growth and biomass parameters, WUE and both nutrient removal and nutrient use efficiency generally tended to increase with increase in nitrogen level under both rainfed and irrigated conditions. On the other hand, increasing plant population tended to result in a decrease in all growth parameters, while it increased biomass yield per hectare. Finally, the effect of row spacing was inconsistent for the same parameter from one sampling to another one, and from one parameter to another. The chemical characteristics of bark fibre showed inconsistent responses to all agronomic practices. The number of fibre rings and fibre bundles increased with increasing nitrogen level, decreased as plant population increased, but did not show clear trends with regard to row spacing. In general the plants grown under irrigated conditions performed better than those grown under rainfed conditions. The results of this study revealed that under the environmental conditions of Pretoria, nitrogen levels above 100 kg ha-1 applied in two dressings should result in best plant performance, but most benefit could be obtained under irrigated conditions. A plant population of 500,000 plants ha-1 or higher and row spacing wider than 0.34 m proved to be most suitable for both growth and biomass parameters. / Dissertation (MScAgric)--University of Pretoria, 2015. / tm2015 / Plant Production and Soil Science / MScAgric / Unrestricted

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