In the last decade, several novel and cost-effective biological nitrogen removal technologies have been developed. The discovery of anaerobic ammonium oxidation (Anammox), about 15 years ago, has resulted in new opportunities for research and development of sustainable nitrogen removal systems. Compared to conventional nitrification/denitrification, Anammox eliminates necessity of external organic carbon source, has a smaller production of excess sludge, reduces energy demand for aeration (up to 60-90%) and CO₂ emissions (up to 90%). Systems based on Anammox can be of great help to comply with stricter wastewater discharge regulations and reduce environmental problems caused by nutrients discharges (e.g. eutrophication).

This thesis investigates the partial nitritation/Anammox in one stage system under oxygen limited condi-tions (also called CANON or Deammonification) and with the Moving Bed Biofilm Reactor (MBBR™) technology. Anammox process coupled with partial nitritation can be particularly suitable to treat ammo-nium-rich wastewater with low content of biodegradable organic matter, such as the reject water from dewatering of digested sludge, which is usually recirculated back to the main stream of wastewater treat-ment plants, accounting for the 15-20% of the total nitrogen load.

Partial nitritation/Anammox process was successfully tested on a pilot plant scale for four months at 25°C, in a 200 L Continuous Stirred Tank Reactor (CSTR), filled with 40% of Kaldnes media (model K1). At an Ammonium Surface Load (ASL) of 3.45 gN m^-2d^-1, the removal rate was about 2.85 gN m^-2d^-1. Removal efficiencies of 95%, 85% and 83% were respectively achieved for NH4+-N, inorganic nitrogen, and Total Nitrogen (TN). Bacteria activity was followed by batch tests such as Specific Anammox Activity (SAA), Oxygen Uptake Rate (OUR) and Nitrate Uptake Rate (NUR), which revealed an increase in activi-ty for Nitrosomonas and Anammox bacteria within the biofilm. Dissolved oxygen concentration in the bulk liquid was a crucial parameter, whereas pH and conductivity turned out to be two useful monitoring tools.

Two laboratory-scale reactors were previously run for two months each, in order to evaluate the one-stage partial nitritation/Anammox process with a lower ASL. One reactor was fed with diluted reject water, whereas the other one treated the effluent from UASB (Up-flow Anaerobic Sludge Blanket) reactor after sand filtration. Fairly good efficiency (>75%) were reached but, however, in the last case the low ammo-nium nitrogen load could represent a problem for a stable full-scale installation and long-term growth of Anammox bacteria.

Some suggestions for full-scale implementation and further research are proposed in the last chapter of this master thesis.

The legal requirements for wastewater discharge into environment, especially to zones exposed to eutrophication, lately became stricter. Nowadays wastewater treatment plants have to manage with the new rules and assure better biogenic elements’ removal, in comparison with the past. There are some well-known methods of diminishing concentrations of these compounds, but they are ineffective in case of nitrogen-rich streams, as landfill leachate or reject waters from dewatering of digested sludge. This wastewater disturbs conventional processes of nitrification-denitrification and raise necessity of building bigger tanks. The partial nitritation followed by Anaerobic Ammonium Oxidation (Anammox) process appear to be an excellent alternative for traditional nitrification/denitrification. The process was investigated in three different reactors – Membrane Bioreactor (MBR), Moving Bed Biofilm Reactor (MBBR) and Rotating Biological Contactor (RBC). The process was evaluated in two options: as a two-stage process performed in two separate reactors and as a one-stage process. The two-step process, in spite of very low nitrogen removal rates, assured very high nitrogen removal efficiency, exceeding even 90% in case of the MBBR. However, obtained results revealed that the one-step system is a better option than the two-step system, no matter, what kind of nitrogen-rich stream is taken into consideration. Moreover, the one-step process was much less complicated in operation. Performed research confirmed a hypothesis, that the oxygen concentration in the bulk liquid and the nitrite production rate are the limiting factors for the Anammox reaction in a single reactor. In order to make a quick and simple determination of bacteria activity, the Oxygen Uptake Rate (OUR) tests were shown as an excellent tool for evaluation of the current bacteria activity reliably, and without a need of using expensive reagents. It was also shown, that partial nitritation/Anammox process, could be successfully applied at temperatures much lower than the optimum value. Performed Fluorescent in situ Hybridization (FISH) analyses, proved that the Anammox bacteria were mainly responsible for the nitrogen removal process.

A biofilm system with Kaldnes biofilm carrier was used in these studies to cultivate bacteria responsible for both partial nitritation and Anammox processes. Due to co-existence of oxygen and oxygen-free zones within the biofilm depth, both processes can occur in a single reactor. Oxygen that inhibits the Anammox process is consumed in the outer layer of the biofilm and in this way Anammox bacteria are protected from oxygen. The impact of oxygen concentration on nitrogen removal rates was investigated in the pilot plant (2.1 m(3)), supplied with reject water from the Himmerfjarden Waste Water Treatment Plant. The results of batch tests showed that the highest nitrogen removal rates were obtained for a dissolved oxygen (DO) concentration around 3 g O(2) m(-3). At a DO concentration of 4 g O(2) m(-3), an increase of nitrite and nitrate nitrogen concentrations in the batch reactor were observed. The average nitrogen removal rate in the pilot plant during a whole operating period oscillated around 1.3 g N m(-2)d(-1) (0.3 +/- 0.1 kg N m(-3)d(-1)) at the average dissolved oxygen concentration of 2.3 g O(2) m(-3). The maximum value of a nitrogen removal rate amounted to 1.9 g N m(-2)d(-1) (0.47 kg N m(-3)d(-1)) and was observed for a DO concentration equal to 2.5 g O(2) m(-3). It was observed that increase of biofilm thickness during the operational period, had no influence on nitrogen removal rates in the pilot plant.

Leachate from landfills is a highly complex polluted wastewater. Landfill leachate with a high concentration of ammonium nitrogen is generally difficult to treat efficiently. Furthermore, it can be very expensive when there is a lack of an easily biodegradable carbon source. Combination of the nitrification/denitrification with the Anammox process can be a very attractive alternative. For the purpose of this study, a Rotating Biological Contactor (RBC) was used. The main objective of the research was to investigate the performance of the Anammox process that occurs together with heterotrophic denitrication in the same RBC. During the operation period, the acclimation of biofilm to the Anammox process was successful at temperature not exceeding 20C. Apparently, the process was not affected by a high concentration of nitrite up to 100 g NO2 Nm3. Additionally, it was shown that the Stover-Kineannon model could be used for description of the ammonium and nitrite removal rates.

Leachate from landfills is a highly complex polluted wastewater. Landfill leachate with a high concentration of ammonium nitrogen is generally difficult to treat efficiently. Furthermore, it can be very expensive when there is a lack of an easily biodegradable carbon source. Combination of the nitrification/denitrification with the Anammox process can be a very attractive alternative. For the purpose of this study, a Rotating Biological Contactor (RBC) was used. The main objective of the research was to investigate the performance of the Anammox process that occurs together with heterotrophic denitrication in the same RBC. During the operation period, the acclimation of biofilm to the Anammox process was successful at temperature not exceeding 20C. Apparently, the process was not affected by a high concentration of nitrite up to 100 g NO2 Nm³. Additionally, it was shown that the Stover-Kineannon model could be used for description of the ammonium and nitrite removal rates.

The influence of the operational variables on the Anammox process has been generally researched considering each variable separately. However, the optimization of the process also requires the identification of the more significant variables and their possible interactions. Response surface models were successfully applied to evaluate the performance of the Anammox process in a deammonification system (i.e., one-stage biofilm Anammox process) taking into account the combined effects caused by two sets of three variables. Specific Anammox activity was measured by a manometric method and used as the response variable. The obtained models pointed out that the significant variables were the temperature, the value of pH, and the ratio between the unionized species of the substrates (free ammonia and free nitrous acid (FA/FNA)). There were interactions among them caused by chemical equilibriums. Total nitrogen concentration and ammonium concentration were found to be not significant in the tested range. According to the models, the optimum values of temperature, pH, and free ammonia to free nitrous acid ratio within the test ranges were, respectively, 30A degrees C, 7.0, and 0.3. Further research at higher temperatures and lower values of pH and FA/FNA ratios would be necessary in order to find the absolute optimum conditions for the process. The obtained model can be also useful in order to develop control strategies that take into account the significant variables and their optimum ranges. A strategy to control deammonification reactors has been proposed, according to the results of the modeling.

Solute transport takes place in heterogeneous porous formations, with the log conductivity, Y = ln K, modeled as a stationary random space function of given univariate normal probability density function (pdf) with mean < Y >, variance sigma(2)(Y), and integral scale I-Y. For weak heterogeneity, the above mentioned quantities completely define the first-order approximation of the longitudinal macrodispersivity sigma(L) = sigma I-2(Y)Y. However, in highly heterogeneous formations, nonlinear effects which depend on the multipoint joint pdf of Y, impact alpha(L). Most of the past numerical simulations assumed a multivariate normal distribution (MVN) of Y values. The main aim of this study is to investigate the impact of deviations from the MVN structure upon alpha(L). This is achieved by using the concept of spatial correlations of different Y classes, the latter being defined as the space domain where Y falls in the generic interval [Y,Y + Delta Y]. The latter is characterized by a length scale lambda(Y), reflecting the degree of connectivity of the domain (the concept is similar to the indicator variograms). We consider both "symmetrical" and "non-symmetrical" structures, for which lambda(Y') = lambda(-Y') (similar to the MVN), and lambda(Y') not equal lambda(-Y'), respectively, where Y' = Y - < Y >. For example, large Y zones may have high spatial correlation, while low Y zones are poorly correlated, or vice versa. The impact of lambda(Y) on alpha(L) is investigated by adopting a structure model which has been used in the past in order to investigate flow and transport in highly heterogeneous media. It is found that the increased correlation in the low conductive zones with respect to the high ones generally leads to a significant increase in alpha(L), for the same global I-Y. The finding is explained by the solute retention occurring in low Y zones, which has a larger effect on solute spreading than high Y zones. Conversely, alpha(L) decreases when the high conductivity zones are more correlated than the low Y ones. Dispersivity is less affected by the shape of lambda(Y) for symmetrical distributions. It is found that the range of validity of the first-order dispersivity, i.e., alpha(L) = I-Y sigma(2)(Y), narrows down for non-symmetrical structures.

Seawater flue gas desulphurization (SWFGD) is a reliable and efficient process to re-move sulfur dioxide in flue gases in power plants and industries. The characteristics and applications of seawater treatment plant of three SWFGD process are described firstly. A literatual survey looking at different air injection techniques in shallow water basin applications are investigated, also including best practice from similar applications in other types of industries. A number of promising alternatives is then selected and compared with today’s system. The relevant experimental data of these systems are collected. A rate-based model is developed to simulate and optimize the aeration process in seawater treatment plant after its reliability is verified by the experimental data.

This study examines the use of MnO₂ and KMnO₄ as strong oxidants to remove specific recalcitrant organic compounds and COD from wastewater. These compounds are deemed as potential and more cost-effective treatment in encountering the challenge to remove Pharmaceuticals and Personal Care Products (PPCPs) and Endocrine Disrupter Compounds (EDCs) in wastewater to meet water reuse standard. The literature reviews concluded that both MnO₂ and KMnO₄ were able to remove recalcitrant organic compounds, such as 17α-ethynylestradiol (EE2), Bisphenol A (BPA), triclosan, and dye wastewater. Simple bench scale experiments were performed to investigate COD removal by utilizing MnO₂ and KMnO₄ to oxidize sewage water and supernatant in a continuously stirred tank reactor at the wastewaters’ natural pH (about pH 8). The results indicated that MnO₂ was effective in removing COD of wastewater and not affected by the high content of suspended solids. The effectiveness of KMnO₄ in removing COD of wastewater was masked by its ability to break down and solubilize particulate organic compounds. MnO₂ application could not be mixed with the presence of other metal ions (or flocculants) as their presence may inhibit the efficiency of MnO₂ oxidation. On the other hand, KMnO₄ oxidation efficiency was not affected and even was enhanced by the presence of magnesium and calcium ions as flocculants.

The ever-increasing population in the metropolis of Accra, Ghana resulting in con-cerns for finding lasting solutions to manage large volumes of waste produced can be tackled through composting for urban agriculture. With insanitary land filling serving as the major disposal option in the metropolis, plans to build the first ever sanitary landfill facility in the metropolis calls for measures to be taken in order to prolong the lifespan of the facility. This therefore necessitates the need to look into an alternative means of diverting organic waste from landfills. The objective of this research is to re-view the Municipal Solid Waste (MSW) management situations in Accra Metropolitan Assembly upon which an investigation is made into the various process steps involved in aerobic windrow composting and also finding out the possibility for integrating composting with urban agriculture.

The study relied mainly on secondary data obtained from books, published articles, governmental documents, internet, and master thesis reports on related topics. By the help of a causal loop diagram, the interdependence of various policy actions and sys-tem elements in the waste management process are linked to illustrate the possibility of a composting programme for urban agriculture.

Even though the metropolis for some time back has been operating a centralized composting facility, the facility is confirmed to be closed down due to problems ema-nating from financial inadequacy, power failure and mechanical breakdown. The study delve into the process steps in windrow composting and finally identified potentials for composting in the metropolis but however enumerated constraints ranging from human and environmental health, financial, institutional, policy directives, to public and leadership attitudes as stumbling blocks to the implementation of a centralized composting scheme.

It finally concluded that the metropolis has the potentials to embark on composting for urban agriculture however, until measures are taken to overcome these constraints, implementing a centralized composting scheme in the metropolis may not be a sustainable option. It is further recommended that whiles the city authorities continue to tackle the constraints to pave way for the implementation of the program, efforts must be made in promoting small scale composting that rely on manually operated tools to help reduce organic waste loads in the municipal waste stream.

For enhancing anaerobic sludge digestion and biogas recovery, an increase in organic load rate (OLR) from 1.0 to 3.0kgVS/(m³·day) was imposed upon a new anaerobic digestion process combined with a sludge recirculation. The new setup requires a traditional mesophilic anaerobic digester coupled with a centrifuge for maintaining relatively high solid content within the digester.

The hypothesis of this study was that increasing continuously OLR from 1.0 to 3.0kgVS/(m³·day) in a pilot-scale anaerobic digester with recycled sludge would not badly influence the digester stability, based on which biogas production would be enhanced. To test this hypothesis, a continuous 73-day study with laboratory experiment was conducted. Due to scarcity of original feeding sludge and its deteriorating quality, OLR had to be increased relied on introduction of extra sludge followed by measurement of total solid (TS) and volatile solid (VS) contents in both feeding sludge and digester sludge, for calculating OLR and examining its variations. To assess the relationship between biogas production and OLR, a measurement of gas yield and methane content was a necessity, performed by applying a biogas flow meter and MSA AUER EX-METER II (P). Moreover, temperature, pH value, volatile fatty acid (VFA) and alkalinity must be tested frequently, for the purpose of preventing system failure.

The results demonstrate that the digester succeeded in withstanding an OLR up to 3.15kgVS/(m³·day). Furthermore, an enhancement in biogas yield and methane content were observed after increasing the OLR by introducing extra sludge. Biogas production measurement performed during this study indicated that biogas yield was enhanced by 73%, with a maximum production of 14.5m³/day, when OLR was increased from 2.05 to 3.15kgVS/(m³·day). However, methane content was merely promoted by 10.5%, to the highest value of 63%, with the same increase in OLR. Specific gas production (SGP), as another means of evaluating the relationship between biogas production and OLR, was observed to be 0.65Nm³/kg VS_in averagely.

A relationship exists between total pollution emission and resources depletion, population, produced goods per capita, and pollution emission and resources depletion per unit of goods. As population and products per capita grow pollution emission and resources depletion per unit of goods must decrease significantly each year to comply with sustainability. Integration of water, wastewater, and solid waste handling and its relation to energy is discussed as a way to improve the direction towards sustainability and to use ecology concepts on water and sanitation in municipalities or river basins. Possible benefits of integration of water and sanitation are discussed and the need to consider natural, technical, social and economical sciences.

Possible benefits of integration of water and sanitation are discussed based on results from a Polish-Swedish research co-operation project supported by the Swedish Institute (SI). A relationship exists between total pollution emission and resources depletion, population, produced goods per capita, and pollution emission and resources depletion per unit of goods. As population and products per capita grow pollution emission and resources depletion per unit of goods must decrease significantly each year to comply with sustainability. Integration of water, wastewater, and solid waste handling and its relation to energy is discussed as a way to improve the direction towards sustainability and to use ecology concepts on water and sanitation in municipalities or river basins.

Manganese compounds have a high potential for treating wastewater, both for utilizing its oxidation, flocculation ability and catalyst ability in anaerobic nitrification. The promising use of manganese compounds (such as permanganate and manganese dioxide) is regarded as an effective method of treating organic compounds in wastewater from municipal and industrial wastewater. Now it is newly realized possibilities to combine manganese compounds with Microbial Fuel Cell technology.

Aiming at reusing the biomass in anaerobic digested sludge for degrading organic pollutants and simultaneously recovering electric energy, Single-chamber Microbial Fuel Cell (SMFC) system was developed and investigated during the main experimental part. Considering the electricity generation rate and characteristics of cathode, MnO₂ was used as the reactant on the cathode electrode; meanwhile, the substrate types in anode compartment also were investigated and then extra sodium acetate was added to investigate the power generation performance.

Two parts of the research were carried out during the whole project. The chemical treatment part was mainly designed to find out the best dosage of KMnO₄ in flocculation when concurrent reacted with magnesium and calcium compounds when treating reject wastewater from digester at Hammarby Sjöstadsverk. The other part was studied to see whether it is possible to improve electricity generation by degrading organic pollutants when MnO2 was used as a cathodic reactant in sediment microbial fuel cell which consisted of anaerobic digested sludge from UASB.

The management of the organic fraction of municipal solid waste has become a major issue lately in the province of Québec, Canada. Most of it is landfilled today, which increases the burden on landfills and is environmentally unsound. In order to comply with new government guidelines, municipalities have to develop solutions to recover and recycle organic waste. In this context, this study examines two solutions for treating organic waste: home-composting and a separate biodegradable waste collection system combined with large-scale composting. The two scenarios are compared in terms of costs and environmental performance to a reference scenario where all waste is landfilled, using as a case study a fictional city of 50 000 inhabitants. Results indicate that a centralized collection system, combined to large-scale composting, has greater environmental benefits than home-composting. It cuts greenhouse gas emissions by 240% compared to the reference scenario, while emissions from home-composting remain at the reference level. However, when compared to the reference scenario, home-composting reduces waste management costs by 15% while they represent an increase of 4% with large-scale composting. The study concludes that separate biodegradable waste collection combined to large-scale composting is the best way for a municipality to achieve high environmental goals, despite a slight increase of municipal costs. The participation rate of citizens is suggested to be a crucial parameter for the success of organic waste management in the two scenarios and it should be enhanced by different means to ensure the successful implementation of the chosen solution.

To minimise the formation of chlorination by-products (CBPs) it is imperative that attention is directed towards the structure and occurrence of natural organic matter (NOM) in raw water sources, and its flow and fate during water treatment processes. In this study, an assessment of the characteristics and flow of NOM along the treatment train at the full scale treatment plant at Masaka, Uganda, was made. Results indicated that 79% of the NOM, determined as total organic carbon, was in the dissolved form (DOC) with 83% of the DOC being hydrophilic in character. The insignificant amount of hydrophobic fraction in the raw water implies that the contributing fraction to THMs formation was mainly the hydrophilic component which subsequently was poorly removed along all units except clarification. The treated water from all unit processes provided specific ultraviolet absorbance values greater than 2 L/mg-m at 254 nm wavelength, indicating that it still had a high potential of reacting with chlorine to form CBPs. This renders water from Nabajjuzi River as unsuitable for chlorination in early stages of treatment and necessitating modification of the processes to reduce or avoid formation of unwanted by-products.

Removal of natural organic matter and iron co-existing in water source is a challenge and a major problem in the developing world where the most commonly applied process in water treatment is pre-chlorination which results in early formation chlorinated by-products. Results from this study proved that horizontal roughing filter system with natural pumice is a promising option for pre-treatment of such waters. The filter recorded average reductions of total and ferrous iron of 39% and 89%, respectively, and trihalomethanes formation potential of 35% after 1 hour and 29% after 6 hours along the filter. Further reductions of 49% and 61% were achieved when the pretreated water was subjected to coagulation.

Chlorine is used as a disinfectant and an oxidant in drinking water treatment to protect the public health from pathogenic microorganisms. However, if applied to raw water with humic materials, it leads to the formation of halogenated organic compounds that are a potentially serious environmental and health problem. This renders pre-chlorination of raw waters to oxidise iron inappropriate. Coagulation, the principal treatment process for removal of THM precursors, is therefore essential for chlorination by-product control. In this study, the impact of pre-chlorination and the performance of Moringa oleifera as a coagulant aid at Masaka waterworks were assessed. An average increase of trihalomethanes of over 4,000% at aeration and pre-chlorination stage was observed at the plant. From the jar tests, alum with Moringa oleifera reduced dissolved organic concentration by 47.1%. The treated water after sedimentation tasted salty but after filtration and chlorination, the salty taste disappeared. Residual iron values of 1.38 mg/L and 3.05 mg/L were achieved with MOC-SC as coagulant aid and alum alone respectively. The jar test results indicated that use of alum with Moringa oleifera as coagulant aid is promising as a first stage in the treatment train for waters with humic materials and high content of iron

Conductivity measurements can be used to monitor the processes in wastewatertreatment that causes changes in conductivity. The processes that in many treatment plants causechanges in conductivity are mainly biological nitrogen removal. Conductivity measurements fromtwo WWTP in Stockholm show no reduction of conductivity in the presedimentation and 21 and28% reduction in the activated sludge process. The conductivity in the inflowing wastewater toLotsbroverket WWTP in Mariehamn, Åland, during 2006 varies from 58 mS/m to 137 mS/m withabout 23% reduction of conductivity in the activated sludge process. At Duvbacken WWTP inGävle, which have biological phosphorus removal and no nitrogen removal, the conductivityvaried between 60 and 100 mS/m with no difference between influent and effluent. Biological Premovalwill give a reduction with 344 to 278 μSm2/g P. However, since the contribution ofphosphate ions can be calculated to about 1 % of measured conductivity phosphorus removal willnot give any decrease in conductivity. Since ammonium nitrogen and alkalinity, which is reducedat biological nitrogen removal, contributes to conductivity with about 33 % and 14 % respectively,it is the three WWTP with biological nitrogen removal that has a decrease in conductivity in thetreatment process. At chemical phosphorus precipitation phosphate will substituted with sulfateand no reduction in conductivity will be achieved. Reduction of conductivity due to biologicalnitrogen removal will consume alkalinity or hydroxide ions. If the amount of available alkalinity ishigh enough (one mole alkalinity per mole ammonia) biological N-removal through nitrificationfollowed by denitrification will give a decrease of conductivity with 842 μSm2/g N. Separationprocesses such as removal of suspended solids through sedimentation or filtration will give nochanges ion conductivity. Separation of nutrients through reverse osmosis will give large changesin conductivity and conductivity can thus be used for controlling the process.

Can wastewater treatment contribute to counteract global warming? Increased biogasproduction for substituting fossil fuel is one possibility. However, using maximum amount of thecarbon source for biogas production there will be no carbon source for biological nutrient removal.This will need development of new methods for nutrient removal without carbon source, for whichstruvite precipitation and can anammox be used. Ozone treatment of digested sludge afterdegassing of CO2 with recycling back to the digestion is a promising method to increase biogasproduction from sludge digestion.At anaerobic digestion half of the energy is utilized as biogas and half remains as organic materialin the digested sludge. To eliminate emission of greenhouse gases from digested sludge, allorganic content in the sludge should be oxidized. At Super Critical Water Oxidation SCWO allorganic content is oxidized and the energy can be utilized.The possibility to use sewage sludge to counteract global warming by recycling carbon to deep seesediments should be studied.

Can wastewater treatment contribute to counteract global warming? Increased biogas production for substitutingfossil fuel is one possibility. However, an active sludge process with biological nitrogen and phosphorus removalconsume organic material, gives a sludge with less digestibility and need energy for aeration. The amountof produced sludge corresponds to half of the organic material in the sewage water. If the degree of digestion is40 % it means that 20 % of the organic content have been transformed to biogas. Anaerobic digestion of thesewage water can give 60 to 80 % conversion of organic material in the sewage water to biogas and thereby 3 to4 times larger biogas production. However, if maximum amount of the carbon source is used for biogas productionthere will be no carbon source for biological nutrient removal. Therefore new methods for nutrient removalwithout carbon source has to be developed, for which struvite precipitation and can anammox be used. Thepilot plant Hammarby Sjöstadsverk is a unique resource owned by KTH and IVL Swedish EnvironmentalInstitute,which can be used for these studies. Also the possibility to use sewage sludge to counteract globalwarming by recycling carbon to deep see sediments should be studied.

In earlier studies sludge incineration ash and SCWO-residues have been leached with acid andbase. Acid leaching gives a high degree of recovery but releases besides phosphate also the mainpart of other metals (including heavy metals). Leaching with base (NaOH) gives a less dissolutionof metals however with lower degree of recovery (up to about 50 %). When leaching with base,the calcium content in the sludge probably binds phosphorus as calcium phosphate.In this study a two-step leaching process has been tested. Ash and SCWO-residues are in the firststep leached with acid, with the main purpose to dissolve calcium. After leaching experiments withhydrochloric acid and acetic acid at different pH-levels from 3 to 6 leaching with acetic acid at pHlevel4 was chosen as the first leaching step. With a weak acid the dissolution reaction can occur atthe desired pH-level without limitation caused by insufficient amount of acid. In the secondleaching step the solid products was leached with 1 M sodium hydroxide. Two-step leaching gavefor SCWO-residue 23% higher leaching of phosphate and for sludge incineration ash 11 % higherleaching. However, aluminium was also dissolved in the second leaching step, and has to beseparated from the phosphate in a third process step.

Phosphate recovery from sludge incineration ash and sludge residues from Super Critical Water Oxidation, SCWO through leaching with acid HCl and base NaOH was studied. Leaching with base gives a selective dissolution of phosphorus but a low degree of recovery compared to leaching with acid. The high per cent of leached phosphorus compared to leached metals at leaching with acid, and the lower cost for acid makes leaching with acid less expensive. The cost for HCl is estimated to 0.32 Euro/kg P and upward. Since calcium may bind phosphorus at leaching with base, a two-step process was tested. A first leaching step with acid at pH-level 4 to dissolve calcium was followed by a second leaching step with base. Two-step leaching gave more leaching of phosphate, however, not as high as for leaching with acid. The cost for chemicals for two-step leaching was estimated to 1.2 Euro/kg P and upward.

Development of methods to recover phosphorus will make handling of sewage sludge moresustainable. In earlier studies sludge incineration ash and SCWO-residues have been leached withacid and base. Acid leaching gives a high degree of recovery but releases besides phosphate alsothe main part of other metals (including heavy metals). This gives a large separation problem andgives a complicated process technology. Leaching with base (NaOH) gives a lower degree ofrecovery (up to about 50 %) however with less dissolution of metals. When leaching with base, thecalcium content in the sludge probably binds phosphorus as calcium phosphate.To improve leaching different possibilities can be studied such as use of a two-step leachingprocess. In a first step acid leaching dissolves calcium and magnesium. Treating the leachate withsulphuric acid, calcium sulphate (gypsum) is precipitated and phosphoric acid is obtained.Remaining ash or SCWO-residual product can afterwards be treated by alkaline leaching. Anotheralternative is to study leaching at anaerobic conditions. Since ferrous iron(II) phosphate is moresoluble than ferric iron(III) phosphate the phosphate is more easily dissolved and the heavy metalcontamination will be lower.

Expected requirements of phosphorus recovery, restrictions on sludge disposal on landfill, and difficulties in obtaining consensus on sludge use on agricultural land has led to several development works in Sweden to change sludge management methods. Especially sludge fractionation has gained interest including following steps to recover products and separate transfer of toxic substances into a small stream. Commercial systems are offered based on technology by Cambi/KREPRO and BioCon and other companies and many other methods are under development. Iron salts are widely used in Sweden as precipitation agents for phosphorus removal and this technology has some disadvantages for phosphorus recovery compared with the use of biological phosphorus removal. The amount of chemicals needed for a KREPRO or a BioCon system was calculated for a treatment plant which has an addition of iron salt resulting in 1,900 mole Fe per tonne DS. The result was compared with the chemical consumption of recovery systems installed at plants with lower use of iron for precipitation. The chemical consumption in equivalents per tonne DS was found to be 5,000 + 6,000 * (molar ratio iron to phosphorus).

Phosphorus can be extracted from side stream hydrolysis in treatment plants with biological phosphorus removal. Soluble phosphate released during the hydrolysis of return sludge is anaerobic treatment where the carbon source is produced from sludge. Different variants for recycling, from the side stream, for example, PhoStrip process in which phosphorus is recovered from the return sludge of phosphorus rich sludge from the activated sludge processes with biological phosphorus removal. Another alternative is to recover phosphorus from a side stream withdrawn from the anaerobic active sludge process, where phosphorus is released to the solution. Phosphorus recovery from phosphorous partial side stream is expected to give a phosphorus recovery of 60-65%. Experiments have been carried out with sludge from side stream hydrolysis at a process with biological phosphorus removal. After separation of the aqueous phase phosphorous was precipitated with both magnesium and calcium, which gave a precipitation of phosphorus at 79 to 100%. At precipitation with magnesium struvite (MgNH4PO4) was formed and calcium phosphate (Ca 10 (OH)2(PO4)6) with calcium. Analysis of the sludge before (100 mg P/l) and the sludge after the hydrolysis shows that 20% phosphorus 20 mg P/l is released to the water phase. With 124 tons per year phosphorus in the incoming sewage and a release of 20 % be in the sludge hydrolysis, the phosphorus recovery potential should be 25 tons per year. However, with a flow of 54 m3/h through the sludge hydrolysis is phosphorus recovery potential will be 9.5 tons per year.

UCO (Ultra Clean Oil) module, an innovative adaption of existing used rolling oil treatment in the Aluminum industry, is being studied for its potential market in China. In this article, conventional used rolling oil treatment process in China has been evaluated and compared with the UCO module in technical and economic aspects. This article also discusses the effect of these two processes on the environment. The UCO module presented in this article, has the potential to significantly reduce the impurities in the used rolling oil and also save the cost for the raw materials, manpower, maintenance and operation for more than 1,600,000 Kr a year. With the new ― state of art‖ equipment, the UCO module has less negative effect on the environment. The UCO module appears to be more efficient but profitability was found to be lower than the conventional process in China.

The influence of selected sulphonamides such as sulphacetamide (SCM) and ptoluenesulphonamide(p-TSA) on the Anammox process was investigated. The short-term (14-hour) and long-term (90-day) exposure of mixed Anammox culture to SCM and p-TSA wasapplied. The aim of long-term exposure study (conducted in continuous-flow bioreactors) was toinvestigate a long-term influence of sulphonamides on Anammox process and on adaptation ofAnammox culture to sulphonamides. The batch test performances resulted in the N-removal ratefor non-acclimated and acclimated Anammox culture. The experiments were carried out atsulphonamides concentration of: 10, 20, 40, 80, 100 and 1000 mg/dm3. The results confirmed thatboth sulphonamides inhibit the Anammox process, however, the effect is more evident in the caseof SCM. The higher the sulphonamides concentration, the stronger inhibition of microorganisms’activity was observed.