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    Application of dissolved air flotation (DAF) to the treatment of dairy wastewaters : a thesis presented in partial fulfilment of the requirements for the degree of Master of Technology at Massey University
    (Massey University, 1993) Susarla, Parthasarathy
    An investigative work was carried out to examine the process performance of dissolved air flotation to remove suspended solids and fat from dairy wastewaters. Suspended solids and fat inhibit advanced treatment systems and cause lot of problems like clogging etc. Traditionally dairy industry uses sedimentation and fat traps to remove solids and fat. Dissolved air flotation is a novel treatment method to purify dairy wastewaters. A laboratory bench scale flotation unit was used to carry out the flotation experiments. The wastewater was collected from a dairy factory manufacturing milk powder and butter. Two types of wastewater was collected, one type (Type-I) of wastewater was used when the plant was manufacturing only milk powder. Type-II wastewater contained discharge from butter plant, thus exhibiting a overall characteristics of the discharges from the plant. The effects of change in pH, temperature and the usage of coagulant alum were examined to assess the process performance of flotation. Experiments with changing the pH showed that pH plays an important role in the treatment of dairy wastewaters. When the pH was lowered to 4 from original pH of wastewater of 11.3, the solids and fat in the wastewater precipitated. High removal efficiencies were obtained at pH 4. Flotation tests were carried out at pH 4, 5, 7, 8 and original pH of wastewater. Considerable removal efficiencies were obtained at pH 7 and 8. This pH range is considered to be effective for further treatment like biological treatment. Temperature studies were carried out at pH 7 and 8. Removal efficiencies were average and were comparable to the removals with pH studies, at temperatures 25° C and 34° C. At a higher temperature of 48° C removal efficiency decreased considerably. Maximum removal efficiencies were obtained for solids and fat at a temperature of 34° C. Coagulant alum was used to increase the removal efficiency of solids and fat. Jar tests indicated that high dosage of alum was necessary to obtain optimum removal efficiencies. Alum was used in the concentrations of 150 mg/l to 400 mg/l. Removal efficiencies upto 92% were obtained for fat and solids. From the experiments it can be concluded that dissolved air flotation is a suitable method for the removal of fat and solids from the dairy wastewater. Scale up experiments can be undertaken before application for large scale treatment system.
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    An investigation of UV disinfection of farm dairy wastewater : a thesis submitted in partial fulfilment of the requirement for the degree of Master of Applied Science in Natural Resources Engineering at Institute of Technology and Engineering, College of Science, Massey University
    (Massey University, 1998) Li, Yongjian
    The development of New Zealand dairy farming industry is characterised by a trend towards more intensified farming operations (larger herd sizes). This is placing greater demand for freshwater uses and effluent discharges. To comply with the microbiological standards, wastewater from farm dairies may be disinfected. Ultraviolet irradiation provides one of the best alternatives to traditional disinfection technologies. With the development of technology and the awareness of the hazards of disinfection by-products, UV irradiation is increasingly used successfully world-wide for both drinking and wastewater disinfection. Due to the lack of data on the nature of farm dairy wastewater, no information was available on the application of UV to dairy effluents. Wastewater samples were collected from farm dairies and analysed for characteristics relative to UV disinfection Suspended solids (SS) contributed to nearly half the COD and 80% of the turbidity of the pond treated wastewater. Colloidal material in the 0.22 to 1.0 micron range constituted nearly 18% of the COD and 15% of the turbidity of the raw pond effluent. Farm dairy wastewater quality changed with season. With the commencing of milking season, wastewater suspended solids, COD, and turbidity increased sharply due to the increased influent loading. However, wastewater BOD was similar over the monitoring period. With the exception of temperature and pH, wastewater quality parameters monitored showed great variation among different sites. These variations may be due to the difference in farm operation and management. Pond treated farm dairy wastewater could not be directly disinfected by UV due to the high suspended solids (317 mg/l), COD (809 mg/l) concentration, high turbidity (450 NTU) and low UV transmittance (0%/cm). Filtration through 1.2, 0.45, and 0.22 micron filter removed all suspended solids and most of the turbidity, but UV transmittance remained lower than 1%/cm. Alum coagulation followed by 0.45 micron filtration removed most of the colloidal material and improved UV transmittance up to 29%/cm. The dissolved organic matter was successfully removed by 0.5 g/l activated carbon (AC) adsorption following aluminium sulphate coagulation treatment. To reach 60%/cm UV transmittance, AC dose of 5 g/l was required for raw pond effluent. Bark and zeolite treatment removed ammonium from farm dairy wastewater. Bark and zeolite treatment did not greatly improve raw pond effluent UV transmittance at 254 nm. Ultracentrifugation at 10,500 g for one hour did not significantly improve UV transmission through alum coagulated farm dairy wastewater. Hydrogen peroxide was found not helpful in improving UV penetration. Strong correlation existed between UV absorbance and COD concentration. UV absorbance may be used as a parameter for estimating wastewater COD level. Keywords: Farm dairy wastewater, ultraviolet (UV), disinfection, dilution, filtration, alum coagulation, hydrogen peroxide, activated carbon, UV transmittance.
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    Biodegradation of cyanobacterial hepatotoxins [Dha⁷]MC-LR and MC-LR by natural aquatic bacteria : a thesis submitted for fulfillment of the requirements for the degree of Doctor of Philosophy in Microbiology, Institute of Food, Nutrition and Human Health, College of Sciences, Massey University at Wellington, New Zealand
    (Massey University, 2010) Somdee, Theerasak
    The aims of this doctoral study were to: isolate naturally occurring bacteria, able to degrade microcystins (MCs), from New Zealand waterbodies; to understand the biological processes of microcystin degradation by bacteria; and to develop small scale biofilm technology for testing the effectiveness of bacteria for microcystin degradation and/or remediation. A significant amount of microcystins were required for biodegradation experiments. A modified method, using DEAE and Strata-X cartridge chromatography, was optimized for purifying microcystin variants from lyophilized bloom samples of the cyanobacterium Microcystis aeruginosa, collected en masse from Lake Horowhenua. Seven microcystin variants, MC-RR, MC-dMe-RR, MC-YR, MC-LR, [Dha⁷]MC-LR, MC-FR, and MC-AR were purified by chromatography and then identified by reverse-phase High Performance Liquid Chromatography (HPLC) with UV detector (UVD) and Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS). A mixture of [Dha⁷]MC-LR and MC-LR, the main microcystin variants present, was used for examining biodegradation of microcystins by degrading bacteria. Three isolates of bacteria—NV-1, NV-2 and NV-3—purified from Lake Rotoiti, New Zealand were capable of degrading [Dha⁷]MC-LR and MC-LR. Among these isolates, NV-3 demonstrated the strongest degradative activity and was identified as a member of the genus Sphingomonas. On the basis of 16S rRNA sequencing, and 100% nucleotide sequence homology, it aligned most closely to strain MD-1. Based on the detection of two intermediate by-products (linearized peptides and a tetrapeptide) and the identification of four genes (mlrA, mlrB, mlrC and mlrD), that encode four putative proteins (enzymes) involved in microcystin degradation, it was suggested that the degradation of [Dha⁷]MC-LR and MC-LR by the Sphingomonas isolate NV-3 occurred by a similar mechanism previously described for Sphingomonas strain MJ-PV (ACM-3962). The bacterium Sphingomonas isolate NV-3 was examined for its ability to inhibit the growth of the cyanobacterium Microcystis aeruginosa strain SWCYNO4. It was found that the bacterium did not have any significant affect on the growth of the cyanobacterium, either by means of secretion of bacterial extracellular products or cell-to-cell contact between bacterial and cyanobacterial cells. It was established that Sphingomonas isolate NV-3 was a moderate biofilm former, based on two types of biofilm formation assays, namely, microtiter plate assays and coupon biofilm assays. This was carried out in preparation for using the bacterium in a bioreactor for biodegradation of [Dha⁷]MC-LR and MC-LR. The bacterium attached most effectively to ceramic, followed by PVC, polystyrene, stainless steel, and finally glass coupons. Biodegradation of MCs by the bacterium, in an internal airlift loop ceramic honeycomb support bioreactor (IAL-CHS bioreactor), was established in batch and continuous-flow experiments. In the batch experiment, NV-3 degraded a combination of [Dha⁷]MC-LR and MC-LR at an initial concentration of 25 µg/ml at 30 degrees C in 30 hours, whereas in the continuous-flow experiment, NV-3 degraded the same concentration of [Dha⁷]MC-LR and MC-LR in 36 hours with an hydraulic retention time (HRT) of 8 hours. This study has demonstrated that microcystin-degrading bacteria are present in New Zealand waterbodies and that these bacteria could be used, potentially on a larger scale, for removing microcystins from water.
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    Studies of magnetic filtration techniques to purify potable water and waste water : a project report submitted in partial fulfilment of the requirement for the degree of Master of Engineering (M.E.) in Information and Telecommunications Engineering, Institute of Information Sciences and Technology, Massey University, Palmerston North, New Zealand
    (Massey University, 2007) De Silva Karunanayaka, Shanaka
    The effects of Electromagnetism on potable water and waste water has been proven in practice but not scientifically proven to the extent that it is accepted by Engineers and Engineering Consultants. The operating principle of magnetic filtration or separation is based on the interaction of electromagnetic fields with the materials under test. Technical water system (TWS) system configuration has been analysed to determine the system characteristics. Three field trials and some laboratory experiments have been reported in this report. Finite element software has been used for the analysis of magnetic field distribution of the TWS system and also for magnetic separation modelling. There is a need to do some more experiments for more convincing and conclusive outcome.