Artificial wetland treatment system is an economical water purification system which has high potential in water purification ecology method. Many countries utilized this natural treatment system to solve their waste problems (for example, wastewater and solid waste) and well results were found with proven efficient. Recently, Taiwan has started developing the natural treatment system utilizing the self-purifying function of the natural surrounding by using the physical, chemical and biological reactions in soil, plants and microorganisms, to reduce the concentrations of pollutants produced by wastes. Eventually, all the pollutants can be eliminated to the harmless level to the environment and its organisms. For better understanding the feasibility of artificial wetlands, we study the performance of artificial wetland system with its raw wastewater produced from its community household wastewater at Liao-Luo Village. Artificial wetland system is a natural purification system, no additional chemicals are needed. In addition, it can be easily operated and maintained, and can be used to treat wastewater with simple pollutants in school. Wetlands not only can be utilized to treat wastewater, but also for can be used for educational purposes. The investigation periods in this work is from May 2008 to Dec.2008. The average of removal efficiency were as follows: BOD (52%), E-colis (79%), NH3 (74%). Total N (61%) and Total P (72%). In comparison with related literatures, we operated with higher removal due to the facts containing the lower organic loading and longer water retention time to decompose pollutants in solution. To keep the Liao-Luo Village wetland¡¦s wastewater treatment function, periodical maintenance is performed. Besides moving grass and removing garbage, proper vegetables are planted in each treatment area are needed.

Industrial flaring can have negative impacts on regional air quality and recent studies have shown that flares are often operated at low combustion efficiency, which exacerbates these air quality impacts. This thesis examines industrial flaring with the objectives of (1) assessing the air quality impacts of flares operating at a variety of conditions, (2) examining the extent to which improvements in flare operations could reduce emissions, (3) identifying opportunities for recycling flared gases in fuel gas networks, and (4) identifying opportunities for reducing the generation of flared gases, using the improved control of catalytic cracking operations as a case study. The work presented in this thesis demonstrates that flares operating at low combustion efficiency can increase localized ambient ozone concentrations by more than 15 ppb under some conditions. The impact of flares on air quality depends most strongly on combustion efficiency, the flow rates to the flares and the chemical composition (photochemical reactivity) of the emissions. Products of incomplete combustion and nitrogen oxides emissions from flaring generally had a smaller impact on air quality than unburned flare gases. The combustion efficiency at which a flare can operate can be constrained by the flare’s design. In a case study of an air-assisted flare, it was demonstrated that choices in blower configurations could lead to emissions that were orders of magnitude greater or less than those predicted using an assumed combustion efficiency of 98%. Designing flares with air-assist rates that can be finely tuned can significantly reduce emissions. Similarly, flaring can be reduced by integrating sources of waste gases into fuel gas networks. Analyses for a petroleum refinery indicated that this integration can often be accomplished with little net cost by expanding boiler capacities. Finally, flared gases can be reduced at their source. A case study of a fluid catalytic cracking indicated that using better temperature control could significantly minimize flared gases. / text

Heavy metals in wastewater can cause serious environmental problems and could beharmful to the human body. Therefore, heavy metals need to be removed from thewastewater. Coagulation based methods are popularly used nowadays with provedeffects. New methods such as the application of nanomaterials have brought morepossibilities to increase the removal effects for certain heavy metals. Among thesenanomaterials, graphene oxide has gained a lot of interest because of its large surfacearea and unique structure. Moreover, graphene oxide is an environmentally friendlymaterial. However, most of the reported studies did not use real wastewater samplesbut simulated ones prepared in labs. Therefore, the removal effects need to beexperimentally evidenced by using real wastewater samples. In this project, I studiedthe removal effects of pristine and modified graphene oxide using wastewatercollected at the wastewater treatment plant in Sundsvall (Fillan wastewater treatmentplant). Moreover, I have also studied the heavy metal removal effects of combinedcoagulation method and graphene oxide. Results have shown that graphene oxide hassimilar removal effects to the coagulation method, indicating the enormous potentialof graphene oxide in wastewater treatment. / <p>2021-09-19</p>

The quality of worlds’ water resources is facing new challenges, for instance detectable concentration of various trace contaminants under the term micropollutants is discharging into water bodies from both municipal wastewater treatment plants and from on-site wastewater facilities. A project called RedMic aim at identifying and quantifying emissions of micropollutants from on-site wastewater treatments as a basis for providing innovative treatment technologies to reduce potential risks for groundwater and surface water contamination. This thesis work deals with two of the work packages in the RedMic project: a column experiment to test the capability of 10 adsorbents to remove micropollutants and a multi-criteria analysis is conducted to evaluate if a filter composed of granulated activated carbon (GAC) or ozonation can be used for on-site wastewater treatment facilities. Based on the removal efficiency of dissolved organic carbon (DOC) of selected adsorbents, two types of activated carbon reduced up to 90% DOC concentration in the effluents. Moreover, six other adsorbents also showed good removal efficiency with around 60% in the second sampling. However, the data used in this thesis was only from the initial part of the experiment that continued and the final results will be published elsewhere. Two system solutions were evaluated with multi-criteria analysis: sandbed filter with either GAC filtration (1) or with ozonation (2) System solution 1 was found to have advantage compared to system 2.

A low-loaded constructed wetland was investigated with respect to phosphorus retention. Since the main long-term phosphorus retention mechanism is sedimentation and sediment accretion, the study focused on these processes. The purpose of the study was 1) to investigate how the calculated value of phosphorus retention (Pin – Pout), corresponded with the measured amount of phosphorus in the sediment, 2) to find out where in the wetland the phosphorus had accumulated, and in what form it was retained, and 3) to investigate the role of vegetation. The calculated value was 12 kg ha-1 and the measured value was 104 kg ha-1, which indicated the importance of internal phosphorus circulation, where plants probably take phosphorus from the underlying clay. Hence, vegetation could possibly increase the total phosphorus content in the wetland. The composition of phosphorus in the sediment was analysed using sequential fractionation. The dominating form of phosphorus in the sediment was iron-bound phosphorus (29 %). In total, 48 % of the phosphorus was stable, i.e. tightly bound in the sediment, and 35 % was relatively stable. The bioavailable fraction, which could cause eutrophication in downstream waters, was 17 % of the total phosphorus content, or 41 kg ha-1. The amount of total phosphorus was significantly higher near the inlet, compared to the outlet, which is explained by rapid sedimentation of particulate phosphorus entering the wetland. The phosphorus amount near the inlet represented 80 % of the total phosphorus load – which indicates the importance of internal circulation of phosphorus, both biological and geochemical.

This research focuses on the performance study of a full-scale biofilter for treating a stream of vent gas with airborne VOCs generated from a chemical plant wastewater treatment facility. The biofilter consists of two parallel 20-ft standard containers in each a space of 5.98 m in length, 2.35 m in width and 0.50 m in height were filled with biofiltering media prepared by blending swine-manure compost and fern chips in a certain proportion. The vent gas contains methane, methanol, ethanol, acetone, dichloromethane, methyl ethyl ketone, ethyl acetate and toluene as major components and has an average flow rate of 1,320 m3/h (22 m3/min) and a temperature of 16-40oC. The purposes of this research were to confirm the VOC removal efficiency and to evaluate the elimination capacity for each VOC by monitoring operating parameters, including gas flow rate, system temperature, influent and effluent VOC concentrations of the biofilter. Experimental results show the system has a volumetric influent gas flow rate 1,153-1,470 m3/h which resulted in an average gas empty bed retention time (EBRT) of 0.64 min through the bed, a moisture of 25-70% and a pH of 2.4-6.9 for the media. Removal efficiencies of methane, methanol, ethanol, acetone, dichloromethane, MEK, ethyl acetate, toluene, NMHC and THC were 23.1, 79.3, 95.2, 82.9, 53.5, 63.7, 83.9, 41.2, 76.2 and 50.5%, respectively. Results also indicate that the VOC removal efficiency for each compound was not directly related to such important operating parameters of the biofilter as influent gas flow rate, media temperature, media pH, and the VOC concentration of the influent gas. However, the volumetric elimination rate (K) was approximately linearly varied with the corresponding loading (L) for the biodegradable VOCs in the influent gas. An average removal efficiency (K/L) of 24.5% was obtained with loadings of L < 70 g/m3h for methane. K/L of 91 and 54% were obtained for methanol with L = 0-7 and 15-22 g/m3h, respectively. Average K/L of 95% was obtained for both ethanol and acetone with L < 40 g/m3h. Removal efficiencies of 48 and 76% were obtained for methanol with L = 0-10 and 18-35 g/m3h, respectively. For MEK, an average removal of 89% was obtained with L = 0.5-4 g/m3h. Removal efficiencies of 84, 37, 48, 76 and 51% were obtained with L < 20, 0-0.2, 0.3-0.8 <60 and <120 g/m3h for ethyl acetate, toluene, NMHC and THC, respectively. This full-scale biofilter is effective in removing ethanol, ethyl acetate, acetone, methanol, and MEK. There is no significant removal efficiency for dichloromethane, toluene and methane. The performance can hopefully be improved by controlling the media in suitable conditions of moisture 50-60% and pH 7-8.

<p> </p><div><table style="height: 340px;" border="0" cellspacing="0" cellpadding="0" width="639" align="left"><tbody><tr><td style="padding: 0cm 7.1pt;" height="289" align="left" valign="top"><div style="border: 1pt solid windowtext; padding: 1pt;"><p class="MsoNormal" style="border: medium none; padding: 0cm;"><span style="font-size: 10pt;" lang="EN-GB">A low-loaded constructed wetland was investigated with respect to phosphorus retention. Since the main long-term phosphorus retention mechanism is sedimentation and sediment accretion, the study focused on these processes. The purpose of the study was 1) to investigate how the calculated value of phosphorus retention (P_in – P_out), corresponded with the measured amount of phosphorus in the sediment, 2) to find out where in the wetland the phosphorus had accumulated, and in what form it was retained, and 3) to investigate the role of vegetation. The calculated value was 12 kg ha^-1 and the measured value was 104 kg ha^-1, which indicated the importance of internal phosphorus circulation, where plants probably take phosphorus from the underlying clay. Hence, vegetation could possibly increase the total phosphorus content in the wetland. The composition of phosphorus in the sediment was analysed using sequential fractionation. The dominating form of phosphorus in the sediment was iron-bound phosphorus (29 %). In total, 48 % of the phosphorus was stable, i.e. tightly bound in the sediment, and 35 % was relatively stable. The bioavailable fraction, which could cause eutrophication in downstream waters, was 17 % of the total phosphorus content, or 41 kg ha^-1. The amount of total phosphorus was significantly higher near the inlet, compared to the outlet, which is explained by rapid sedimentation of particulate phosphorus entering the wetland. The phosphorus amount near the inlet represented 80 % of the total phosphorus load – which indicates the importance of internal circulation of phosphorus, both biological and geochemical. </span></p></div></td></tr></tbody></table></div>

Per- and polyfluoroalkyl substances (PFASs) are chemicals that have been used for over 50 years. They are both hydrophobic and hydrophilic, which make them useful in a wide range of products, both in the domestic and industrial market. Recently, the global attention on PFASs has increased due to their possible harmful health effects on humans. Furthermore, PFASs have been detected in drinking water sources all over the world. Conventional treatment processes in drinking water treatment plants (DWTPs) are not able to remove PFASs. Therefore, more research is required to find efficient removal techniques for these compounds. The aim of this study was to investigate the removal efficiency of PFASs using two different adsorption techniques, anion exchange (AE) with the resin Purolite A-600, and granular activated carbon (GAC) of type Filtrasorb®400. The experiments were performed in laboratory batch-scale, at Swedish University of Agriculture (SLU), and column tests in pilot-scale, at Bäcklösa DWTP in Uppsala. The PFASs showed a high sorption potential to AE and GAC. However, the removal efficiency differed depending on the perfluorocarbon chain length, functional group, and concentration level. For the AE, in average 92 % of the PFASs were removed in the end of the batch experiments while the average removal efficiency in the column experiment was 86 %. In the batch experiments treated with GAC on average 55 % of the PFASs were removed in the end of the experiments while the column experiment had the average removal efficiency of 86 %. There was an increase in the removal efficiency with increasing perfluorocarbon chain length in the column experiments. However, in the batch experiments, the adsorption of PFASs decreased with an increasing chain length, except for the highest PFAS concentration level (5000 ng L-1) treated with AE and the lowest PFAS concentration level (200 ng L-1) treated with GAC. In the column experiments, the perfluoroalkane sulfonates (PFSAs) were slightly better removed than perfluoroalkyl carboxylates (PFCAs) with an average removal efficiency of 97 % for AE and 91 % for GAC compared to 67 % and 82 % for AE and GAC, respectively. In the batch experiments, there was no clear trend between the removal efficiency and functional group. Overall, the pilot-scale experiments removed the PFASs relatively well even after 42 days (on average, 86 % for both AE and GAC). The lowest removal capacity in the column experiments was seen for the shorter chained PFSAs (in average 46 % for ≤C6 PFCAs using AE and 75 % for ≤C7 PFCAs using GAC). More efficient treatment techniques are needed to minimise the PFAS concentrations in drinking water and the potential human. / Per- och polyfluorerade alkylsubstanser (PFASs) är kemikalier som har används globalt under de senaste 50 åren. Tack vare att de är uppbygda av både en hydrofob och en hydrofil del är de ytaktiva (s.k. surfaktanter) och har ett brett användningsområde, både för industri- och hushållsprodukter. På senare år har dessa ämnen fått uppmärksamhet på grund av att exponering för PFASs har visats kunna medföra hälsorisker. PFASs har upptäckts i dricksvatten på många håll i världen, men flera av de konventionella reningsmetoderna för dricksvatten är inte effektiva för PFASs och därför finns ett behov av mer forskning och kunskap inom vattenberedningsområdet. I denna studie undersöktes reningseffektiviteten för PFASs hos två adsorptionstekniker; i) anjonbyte (AE) med Purolite A-600 och ii) granulerat aktivt kol (GAC) med Filtrasorb®400. Studien utformades så att inverkan av kolkedjans längd, molekylens funktionella grupp samt koncentrationsnivån av PFASs kunde utvärderas. Experimenten utfördes både i liten skala genom försök i bägare på Sveriges lantbruksuniversitet (SLU) och i något större skala i en pilotanläggning med kolonnexperiment på Bäcklösa dricksvattenverk i Uppsala.  Båda reningsmetoderna visade god effekvititet för avlägsnandet av PFASs i dricksvatten. I slutet av bägarexperimenten var i medeltal 92 % och 55 % av PFASs eliminerade för de prover behandlade med AE respektive GAC. Reningseffektivititen för kolonnexperimenten var i medeltal 86 % för båda metoderna. Reningsgraden var beroende av längden på den perfluorerade kolkedjan. I kolonnexperimenten visades att ökad kedjelängd ledde till ökad reningseffektivitet, medan bägarexperimenten visade på motsatt trend, med undantag för prover behandlades med AE och PFAS-koncentration 5000 ng L-1 samt prover behandlade med GAC och PFAS-koncentration 200 ng L-1. Reningseffektiviteten varierade också beroende på funktionell grupp, d.v.s. beroende på om det var en sulfonat eller en karboxylat. I kolonnexperimenten avlägsnades de perfluorerade alkylsulfonaterna (PFSAs) i något högre grad (97 % och 91 %; AE och GAC) än karboxylaterna (PFCAs; 67 % och 82 %; AE och GAC). För bägarexperimenten hittades dock inget tydligt motsvarande samband. Sammanfattningsvis renades PFASs från dricksvattnet i kolonnexperimenten relativt väl även i slutet av experimentent (efter 42 dagar). De sämst renade PFAS ämnena var de med kortare kolkedja. Efter 42 dagar hade PFCAs med kolkedjelängd ≤C6 renats bort med 46 % (AE) och på PFCAs med kolkedjelängd ≤C7 med 75 % (GAC). Behovet av bättre reningsmetoder för dessa PFASs är därför stort.

Perfluoroalkylated substances (PFASs) are a group of synthetic compounds that have gained growing attention due to their environmental persistence, toxicity and their potential to bioaccumulate. Even though PFASs are not occurring naturally in our environment, they are globally distributed and can be found ubiquitously in air, water, soil, wildlife as well as in humans. PFASs have primarily been used, due to their unique properties of being both hydrophilic and hydrophobic, as surfactants in numerous products such as firefighting foams, paint, leather and textile coating. The occurrence of PFASs in drinking water as well as in wastewater makes it important to develop effective techniques to remove these compounds from drinking water sources and wastewater. To be able to effectively remove PFASs from drinking water and wastewater it is important to understand which treatment process is most efficient and how the removal efficiency is affected by the physicochemical properties of PFASs and characteristics of water. In this study, the removal efficiency of PFASs was investigated using six different water types with varying dissolved organic carbon (DOC) character. Four different treatment techniques were evaluated including anion exchange using MIEX® resins, coagulation with iron (III) chloride (FeCl3), adsorption using powdered activated carbon (PAC) and nanofiltration (NF) membrane. The batch experiments were performed in laboratory-scale for 14 individual PFASs including C3-11, C13 perfluoroalkyl carboxylic acids (PFCAs), C4, C6, C8 perfluoroalkyl sulfonic acids (PFSAs) and perfluorooctane sulfonamide (FOSA). The results showed that the removal efficiency of PFASs was dependent on both perfluorocarbon chain length as well as functional group, with an increase in removal efficiency with increased perfluorocarbon chain length. Short-chained PFASs (C!6) were removed in less extent than the long chained PFASs for all treatment techniques. Amongst the four treatment techniques investigated, NF membrane exhibited the best removal efficiency for both short- and long chained PFASs (on average, 51%). Lower removal efficiencies for PFASs were observed for MIEX (33%) &lt; FeCl3 (16%) &lt; PAC (14%). However, all tested treatment techniques used in this study exhibited generally low removal efficiency (&lt; 78%), in particular for the short-chained PFASs (C!6, &lt; 41%) Results using three different doses of PAC (i.e. 20, 50, 100 mg L-1) showed an increase in removal (i.e. 2.2-41%, 8.0-78% and 12-92% respectively) with increasing dose. No significant trends were found between PFAS removal and DOC removal for any of the treatments (p&lt;0.05, student t-test). However, the removal efficiency was different of the six different water types, which indicates that the DOC characteristics (i.e. Freshness, humification index, pH and absorbance) have an influence on the removal efficiency of PFASs in water. / Perfluoroalkylerade ämnen (PFASer) är en grupp syntetiska ämnen som har fått allt större uppmärksamhet den senaste tiden då de har visat sig vara persistenta, toxiska och bioackumulerande. Även om PFASer inte förekommer naturligt i vår miljö är de globalt fördelade och kan återfinnas i luft, vatten, mark, djur och hos människor. PFASer har främst använts, på grund av sina unika egenskaper att vara både hydrofila och hydrofoba, som tensider i många produkter såsom brandsläckningsskum, färg, läder och textil. Förekomsten av PFASer i dricksvattentäkter och i många reningsverk gör det viktigt att utveckla effektiva metoder för att ta bort dessa föreningar i vattenreningsverk. För att effektivt kunna avlägsna PFASer från dricks- och avloppsvatten är det viktigt att ha kunskap om vilken behandlingsmetod som är effektivast och hur reningseffektiviteten påverkas av ämnenas fysikalisk-kemiska egenskaper och vattnets karaktär.   Syftet med denna studie var att undersökta reningseffektiviteten för PFASer i sex olika vatten innehållande olika typer av löst organiskt kol (DOC). Detta undersöktes för fyra olika behandlingsteknikert; jonbyte med MIEX®, koagulering med järnklorid (FeCl3), adsorption med hjälp av pulveriserat aktivt kol (PAC) och nanofiltrering. Försöken gjordes små skaligt i laboratorie och 14 olika PFASer undersöktes; C3-11,13  perfluoralkyl karboxylsyror (PFCAer), C4, C6, C8, perfluoralkyl sulfonsyror (PFSAer) och perfluoroktan sulfonamid (FOSA). Resultaten visar att reningseffektiviteten för PFASer var beroende av både den perfluorerade kolkedjans längd och funktionell grupp, med en ökning av reningseffektivitet med längre perfluorerad kolkedja. PFASer med kort perfluorerad kolkedja (C≤6) renades i mindre utsträckning än PFASer med lång perfluorerad kolkedjade; detta gällde för alla behandlingstekniker. Bland de fyra behandlingstekniker som undersöktes uppvisade nanofiltreringen den bästa reningseffektiviteten för PFASer med både korta och långa kolkedjor (i genomsnitt, 51%.). Lägre reningseffektivitet för PFASer observerades för MIEX®(33%), &lt; FeCl3(16%) &lt; PAC (14%). Totalt sett erhölls en relativt låg reningseffektivitet (&lt;78%) för samtliga reningstekniker, speciellt för de kortkedjade PFASer (C£6, &lt; 41%). Resultat från försök med tre olika doser PAC (e.g. 20, 50, 100 mg L-1) visade på en ökad reningseffektivitet (2,2-41%, 8,0-78% och 12-92%) med ökad dos PAC. Inga signifikanta trender kunde urskiljas vad gäller reningseffektivitet av PFASer och rening av DOC (p&lt;0.05, student t-test), detta gällde för samtliga behandlingstekniker. Det fanns dock tydliga skillnader i reningseffektivitet mellan de sex olika vattentyperna vilket indikerar på att DOC egenskaperna (Freshnessindex, humifieringsindex, pH, absorbans) har en påverkan på reningseffektiviteten för PFASer i vatten.

Indicator organisms like coliforms, E. coli and enterococci are normally associated with the intestinal tract of warm-blooded animals, and can thus be used for indicating fecal contamination of water. This study investigated the removal efficiency of indicator organisms in a free water surface constructed wetland used for additional treatment of municipal wastewater. The species composition of enterococci and the prevalence of the tetracycline resistance gene tetM were also investigated. Samplings were done at five different sites: at the inlet, within and at the outlet of the wetland, as well as upstream and downstream of the wetland outlet into the adjoining river. A total of 86 enterococci isolates were characterized as E. faecalis, E. faecium or other Enterococcus spp., and the two former were also screened for the tetM gene. The investigated wetland showed a high removal rate of indicator organisms, with a removal of approximately 98%. E. faecium was identified as the predominant species in the wetland at a mean of 55.8%. In comparison, only 9.3% were E. faecalis, while other Enterococcus spp. were found to comprise 34.9%. Of the 56 isolates identified as E. feacalis or E. faecium 10.7% were positive for the tetM gene. The high removal of bacteria shown by this investigation provides further evidence of the benefits of constructed wetlands on wastewater treatment. It also offers a first indication of the Enterococcus spp. composition in Ekeby wetland, Eskilstuna, Sweden, and shows that the prevalence of the tetM gene is relatively low at this point in time.