In order to encourage the establishment of an erosion controlling vegetative ground cover, low cost organic amendments and inorganic fertilizers were incorporated into an abandoned, non-acid generating mine tailings pond. By amending these gold mine tailings with a small quantity (3.7 kg m-2) of combined papermill sludge and fertilizer, a consistent and robust grass/Medicago sativa sward was established within the first growing season. This tailings amendment and the subsequent plant establishment lead to improvements in substrate fertility characteristics including aggregation, bulk density, as well as cation exchange capacity and organic content. Chemical fertility (available nitrogen and phosphorous) was ameliorated by all initial amendment treatments. However, the effect was relatively short-lived, with all amendment treatments returning to their background levels of these nutrients within one to two years. This study further proves the usefulness of papermill sludge as a low cost amendment for disturbed soil substrates, including mine tailings.

District heating has a long standing tradition in Sweden and today it is the most common way of producing and transporting heat. A District heating system (DH system) is divided into three parts: a production facility, distribution network (DH network) and one more heat stations. The heat produced in the facilities is distributed to the customers via a heat transfer medium, usually water (DH water), in piping networks that make up the DH network. The heat is transferred to the customers via the heat exchanger at which point they can use it as heated tap water or for heating purposes. The DH networks are often constructed in steel as it is cheap and a relatively resistant material. However it has the disadvantages of corrosion and expansions when it is exposed high temperatures which lead to damages in the DH network resulting in loss of the DH water, this is an unavoidable occurrence in any DH network. This results in addition of pollutants by leakages into the DH network or with the water that is used to compensate for the losses. The pollutants cause further corrosion, leading to metal contamination, and more damages on the DH network meaning there is a continuous degradation. Therefore various treatments are used to clean and ascertain an acceptable chemical environment in the DH systems. These treatments are effective but not at a level which is required so many chemicals are used to enhance the treatment of the water. Some of these are known to be toxic to humans and water ecosystems. As leakages are abundant and often end up in the WWTPs of the concerned municipality, which often have troubles with disturbances of the biological treatment, it was decided that an assessment of the toxic effects that DH water pose on activated sludge was to be investigated. This was done by testing water from two DH networks, Växjö and Kalmar, on the same activated sludge obtained from Tegelviken WWTP in Kalmar. A respirometric bioassay approach established by the Organization for Economic Co-operation and Development (OECD), OECD standard 209; OECD Guidelines for the Testing of Chemicals was used with changes made to exposure and measuring time as this decrease the risk of misinterpretation of the results. A dilution series using different concentrations (6.25%, 25% and 100%) of DH water was tested and compered to a blank control samples containing only activated sludge. Assessment of toxicity on total oxidation, oxidation carbon and oxidation of nitrogen was made. To get some idea of what might cause toxic effect samples of the waters was sent to outside laboratories for analyses of metals. The result from the bioassay and metal analysis was used to formulate risk factors associated with a DH water spill and exposure to WWTPs. It was found that both DH waters have a significant inhibition on nitrification in WWTPs. The DH water from Kalmar exhibited similar toxicity dynamics, roughly 20% inhibition, despite large differences in concentration. The DH water from Växjö showed a negative correlation between an increase in concentration of DH water and toxicity, 74% for the lowest concentration and 11% for the highest. The metal analysis concluded that there was no abundance of metal contamination which led to the inference that toxicity is probably caused by the chemicals used for treatment. This poses a great risk for the Baltic Ocean as many WWTPs release their treated water directly into water courses with a short detention time before reaching the sea.

From June to November 2007, a microscopic analysis was conducted on the activated sludge from eleven selected wastewater treatment plants (WWTP's) belonging to the City of Cape Town. The primary objective was the identification of the dominant and secondary filamentous organisms. Other important criteria included were the floe character, diversity, filament index (Fl) and identification of the protozoan and metazoan communities. The operational data determined from routine analyses of the sludge, influent and effluent were used to assess the relationship of the filamentous population to wastewater characteristics and to compare this with previous findings. Fl values of >3 and dissolved sludge volume indices (DSVI's) of >150 were chosen as representing the possibility of bulking conditions being present. The five most prevalent dominant filaments were Type 0092, Type 1851, actinomycetes, Microthrix parvicella and Type 021N, being present in 74%, 31%, 22%, 17% and 14% of samples respectively. Type 0092 did not appear to be associated with bulking in any of the WWTP's, although it was often incidentally present as a co-dominant species when bulking conditions existed. All three WWTP's with the Modified Ludzack-Ettinger configuration harboured Type 1851 as the major dominant species, irrespective of whether the plants treated domestic or industrial effluent. Conditions suggestive of bulking were present in two of these WWTP's. Contrary to expectations, Type 1851 was often found as a dominant species where domestic waste was the primary influent. Type 021N and actinomycetes were strongly implicated when bulking occurred. The overgrowth of these filaments appeared to be related to factors such as nutrient deficiency (Type 021N) or the presence of large amounts of low molecular weight substances in the influent. Microthrix parvicella did not cause major bulking problems. There was a strong association between low levels of nitrates/nitrites in the clarifier supernatant and good phosphorous removal, irrespective of the configuration of the WWTP. The converse was also true. / Thesis ((M. Environmental Science))--North-West University, Potchefstroom Campus, 2009.

From June to November 2007, a microscopic analysis was conducted on the activated sludge from eleven selected wastewater treatment plants (WWTP's) belonging to the City of Cape Town. The primary objective was the identification of the dominant and secondary filamentous organisms. Other important criteria included were the floe character, diversity, filament index (Fl) and identification of the protozoan and metazoan communities. The operational data determined from routine analyses of the sludge, influent and effluent were used to assess the relationship of the filamentous population to wastewater characteristics and to compare this with previous findings. Fl values of >3 and dissolved sludge volume indices (DSVI's) of >150 were chosen as representing the possibility of bulking conditions being present. The five most prevalent dominant filaments were Type 0092, Type 1851, actinomycetes, Microthrix parvicella and Type 021N, being present in 74%, 31%, 22%, 17% and 14% of samples respectively. Type 0092 did not appear to be associated with bulking in any of the WWTP's, although it was often incidentally present as a co-dominant species when bulking conditions existed. All three WWTP's with the Modified Ludzack-Ettinger configuration harboured Type 1851 as the major dominant species, irrespective of whether the plants treated domestic or industrial effluent. Conditions suggestive of bulking were present in two of these WWTP's. Contrary to expectations, Type 1851 was often found as a dominant species where domestic waste was the primary influent. Type 021N and actinomycetes were strongly implicated when bulking occurred. The overgrowth of these filaments appeared to be related to factors such as nutrient deficiency (Type 021N) or the presence of large amounts of low molecular weight substances in the influent. Microthrix parvicella did not cause major bulking problems. There was a strong association between low levels of nitrates/nitrites in the clarifier supernatant and good phosphorous removal, irrespective of the configuration of the WWTP. The converse was also true. / Thesis ((M. Environmental Science))--North-West University, Potchefstroom Campus, 2009.

The effects of sewage sludge application and the additional effects of clearfelling on nutrient cycling have been assessed in a mature Scots pine stand, north-east Scotland. The forest site was situated in a low rainfall area with high evapotranspiration and low leaching losses. The ground vegetation formed an important sink for N and P following sludge addition and clearfelling. Sludge application caused a foliar N response, increased foliar needle weight, and litterfall showed a significant and rapid potential to immobilize NH₄-N and PO₄-P added in sludge. The soil availability of NH₄-N and PO₄-P together with rates of mineralization of N and P and nitrification in sludge-treated areas were significantly increased compared with that of the control. Concentrations of NH₄-N, NO₃-N, PO₄-P and organic P were increased significantly following sludge addition and fluxes were an order of magnitude greater than that of the control. Peaks in concentrations of NH₃-N in sludge-treated areas exceeded the EC limit of 11.3 mg 1^-1 on several occasions. Of the total N and P applied to the sludge, throughfall and litterfall over a 17 month period, 2.4 % and 0.72 % were measured in the B_s soil horizon flux. After clearfelling, initial increases in soil availability of NH₄-N, NO₃-N andPO₄-P were measured. Felling increased nitrification rates, although increases were significant only in areas previously treated with sludge. Fluxes of NO₃-N, NH₄-N and PO₄-P and organic P were increased at least an order of magnitude greater in felled areas than those of the control. Immobilization of N and P was greater in green and abscised litters placed in previously sludge-treated areas than compared with those placed in control areas.

This thesis was the report of the research done on the near-critical water gasification (NCWG) as an application for activated sludge treatment. The research started with the use of model compounds and binary mixtures of these compounds as feeds for the NCWG. High gasification yields were obtained using a commercial catalyst (Raney nickel), and it was found that interactions between model compounds in the binary mixtures resulted in lowering the gasification efficiencies. The research then shifted to the use of actual activated sludge samples and the search for novel catalysts for that application. Almost 70% of the sludge was gasified in the presence of the high amounts of Raney nickel. Hydrogen was the main product in the gas phase. However, Raney nickel lost half its activity after only 8 minutes of exposure to supercritical water. For some model compounds, novel catalysts formulated in our laboratories had better activities than the commercial ones. This was not the case for the NCWG of activated sludge.

This thesis was the report of the research done on the near-critical water gasification (NCWG) as an application for activated sludge treatment. The research started with the use of model compounds and binary mixtures of these compounds as feeds for the NCWG. High gasification yields were obtained using a commercial catalyst (Raney nickel), and it was found that interactions between model compounds in the binary mixtures resulted in lowering the gasification efficiencies. The research then shifted to the use of actual activated sludge samples and the search for novel catalysts for that application. Almost 70% of the sludge was gasified in the presence of the high amounts of Raney nickel. Hydrogen was the main product in the gas phase. However, Raney nickel lost half its activity after only 8 minutes of exposure to supercritical water. For some model compounds, novel catalysts formulated in our laboratories had better activities than the commercial ones. This was not the case for the NCWG of activated sludge.

Thesis (M.S.)--University of Nevada, Reno, 2006. / "August, 2006." Includes bibliographical references (leaves xx-xx). Online version available on the World Wide Web.

Diss. (sammanfattning) Uppsala : Sveriges lantbruksuniversitet, 2005. / Härtill 4 uppsatser.

Lic.-avh. (sammanfattning) Uppsala : Sveriges lantbruksuniv., 2004. / Härtill 2 uppsatser.