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Item 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, YongjianThe 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.Item Enhancing harvestable algal biomass production in wastewater treatment high rate algal ponds by recycling : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Environmental Engineering at Massey University, Palmerston North, New Zealand(Massey University, 2013) Park, Byung KwanHigh Rate Algal Ponds (HRAPs) are an efficient and cost-effective system for wastewater treatment and produce algal biomass which could be converted to biofuels. However, little research has been conducted to improve harvestable biomass production from these ponds. Laboratory and small-scale outdoor research reported in the literature indicates that selective biomass recycling is partially effective at controlling algal species in HRAP. This, therefore, offers the potential to select and maintain a rapidly settleable algal species. To date, algal species control of similarly sized, co-occurring algae has not been demonstrated in wastewater treatment HRAPs. Furthermore, the influence of algal recycling on biomass harvest efficiency, harvestable biomass productivity, net biomass energy yield and the growth of the dominant algal species in the HRAPs have never previously been investigated. The main hypothesis of this Ph.D. was: ‘Recycling a portion of gravity harvested biomass (‘recycling’) back into the HRAP improves harvestable biomass production’. To test this, a series of experiments was conducted using pilot-scale wastewater treatment HRAPs, outdoor mesocosms and laboratory microcosms. Firstly, the influence of recycling on species dominance and biomass harvest efficiency was investigated using two identical pilot-scale HRAPs over two years. This pilot-scale study showed that recycling promoted the dominance of a rapidly settling colonial alga, Pediastrum boryanum, and maintained its dominance over the two year experimental period. Moreover, P. boryanum dominance was relatively fast to establish and was then stable and sustainable between seasons. The higher dominance of P. boryanum in the HRAP with recycling improved biomass harvest efficiency by gravity sedimentation from ~60% in the control HRAP without recycling to 85%. Unexpectedly, recycling also improved the ‘in-pond’ biomass productivity by 20%. The combination of the increased biomass productivity of the HRAP and the increased biomass harvestability with recycling improved the ‘harvestable biomass productivity’ by 58%. Overall, recycling increased the net biomass energy yield by 66% through the combined improvements in biomass productivity, harvest efficiency and a small increase in algal biomass energy content. To determine the reproducibility of these findings and investigate the mechanisms responsible, twelve outdoor mesocosms were studied. This mesocosm research repeatedly confirmed that recycling can establish P. boryanum dominance, and improve biomass productivity and settleability. Settleability was not only found to be improved by recycling the ‘solid’ fraction of the harvested biomass but also by recycling of the ‘liquid’ fraction, potentially indicating the presence of extracellular polymeric substances. Several possible mechanisms to explain the increase in biomass productivity were identified. However, after review all but two were discounted: (i) the mean cell residence time (MCRT) was extended thereby increasing the algal concentration and thus allowing better utilization of incident sunlight; and (ii) the relative proportion of algal growth stages (which may have different net growth rates) was shifted, resulting in an increase in the net growth rate of the algal culture. To investigate these mechanisms further, the life-cycle of P. boryanum was studied in detail and showed, for the first time in the literature, that its net growth rate does indeed vary between the three life-cycle stages (‘growth’ > ‘juvenile’ > ‘reproductive’). Given that the mesocosm studies in Chapter 4 showed that recycling increased the number of growth colonies by ~2-fold and juvenile colonies by ~4-fold then it is proposed that mechanism (ii) does appear to be viable. This Ph.D. work has demonstrated that recycling a portion of gravity harvested biomass could be a simple and practical method to enhance biomass productivity, harvest efficiency and energy content, which contribute to achieve higher ‘harvestable biomass productivity’ and ‘energy yield’ in wastewater treatment high rate algal ponds.Item Application of biochar technologies to wastewater treatment : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science, Massey University, Palmerston North, New Zealand(Massey University, 2013) Hina, KiranA review of wastewater treatment options and the properties of biochar (charcoal made from biomass with the intention of carbon sequestration in soil) indicated the potential application of biochar for removal of ammonium-N (NH4+-N) and various organic and inorganic pollutants from wastewaters. This thesis investigates (i) the capacity of alkaline activated and non-activated Pine and Eucalyptus biochars to retain N and P from wastewaters, and (ii) the potential use of these nutrient-rich materials as slow-release fertilisers in soil, thus assisting the recycling of nutrients from waste streams. The retention of NH4+-N on different materials, pine bark, pine biochar (produced from wood chips at 550 °C) and zeolite was investigated. When shaken with a 39 mg NH4+-N L-1 influent solution, Zeolite proved to be the best sorbent of NH4+-N, followed by pine biochar and pine bark; 0.71> 0.38 > 0.27 mg NH4+-N g-1 sorbent, respectively. Ways of increasing the CEC (cation exchange capacity) and NH4+-N sorption capacity of biochar were investigated by (i) alkaline activation by tannery waste or (ii) physical activation using steam as pre and post treatment of biochars, respectively to increase their CEC. Washed alkaline activated biochars (Pine and Eucalyptus) showed a significant (p < 0.05) increase in the NH4+-N sorption capacity over corresponding non-activated biochars. Steam activation increased the internal surface area of biochars but did not prove increased retention of NH4+-N. The efficiency of NH4+-N removal from synthetic NH4+ solutions and urban and dairy wastewaters by alkaline activated and non-activated Pine and Eucalyptus biochars was evaluated and compared using batch and column studies under different flow rates and retention times. Greater NH4+-N sorption was observed in alkaline activated Pine biochar from both the synthetic solution and urban wastewater in column studies @ 2.40 mg N g-1 and 2.17 mg g-1 NH4+-N biochar, respectively. Inclusion of Okato tephra with alkaline activated pine biochar proved effective in removing both P and N from urban wastewater. Finally, the activated pine biochar and tephra loaded with N and P from wastewater treatment were incorporated into two soils (Kiwitea and Manawatu) and the bioavailability of N and P was tested by growing ryegrass in an exhaustive Standford and Dement bioassay. The recovery of N and P was very low and this indicated that it was not economical to use biochar in wastewater treatment for subsequent use as a fertiliser.Item Anaerobic treatment of thermo-mechanical pulp mill waste water : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Process and Environmental Technology at Massey University(Massey University, 1994) Hearn, Christopher RaeThe operation and performance of anaerobic digesters treating thermomechanical pulping wastewater was investigated. The aim of this work was to develop a reactor design that could successfully treat the wastewater with minimal pretreatment. Six reactors were trialed, all modifications of the upflow anaerobic sludge blanket [UASB] reactor design. Seed sludge source, start-up regime and suspended solids retention were varied to determine effective operation methodology. A screw press effluent from Pan Pacific Forestry Industries Ltd thermomechanical pulp [TMP] mill at Whirinaki, North Island, New Zealand was used as feed for all of the reactors. Seed sludge was obtained in granular form from UASB reactors treating dairy industry wastewaters and in nongranular form from the aerated lagoons of the New Zealands central North Island pulp mills. Operation of all six experimental reactors was difficult due to many feed blockages caused by the relatively high suspended solids concentration in the feed. Inhibition was frequently observed after feed interruptions with slow recovery of performance, possibly due to the lack of a co-metabolite soon after the feed supply ceased. Many modifications to the reactor inlet and feed system greatly reduced blockage problems. In the later reactors a low suspended solids retention allowed granulation to be achieved from a non-granular forestry industry sludge. With the final reactor configuration total COD removals of 50-60% and dissolved COD removals of 70-85% were achieved at organic loading rates up to 40 kgCOD.m-3.d-1. A 20 to 50 % conversion of feed suspended solids to methane was calculated on a COD basis. Granulation was achieved without a gas-solids-separator. This was attributed to the need for severe selection against poorly settling wood suspended solids, and the presence and precipitation of iron. The granules were approximately 37% iron on a dry weight basis and had densities averaging 2000 kg.m-3. Scanning electron microscope work indicated that extensive precipitates, presumed to be iron based complexes, were responsible for the structural integrity of the granule. An abundant layer of bacteria of predominantly Methanothrix morphotypes was found beneath the surface of the granules. The granules have been demonstrated to provide some protection from inhibition, probably by diffusional gradients. After five years exposure to TMP wastewater a dissolved extract of feed resin acids exerted an inhibitory effect on granules at similar concentrations to that reported for dehydroabietic acid with unacclimated granules. Thus no acclimation to soluble resin acids was evident. Changes in the distribution of resin acids suggested that some degree of resin acid dissolution occurs within the reactors but degradation of the total concentration of resin acids is poor, averaging 10 % reduction as total acids. Overall, the final reactor design has proved to be an effective treatment of TMP wastewater. Suspended solids removal rates are not high but equally the suspended solids do not threaten the viability of the reactor system. Changes in the nature of the suspended solids passing through the reactor are such that subsequent suspended solids removal will be more efficient and have a lower loading rate than for the untreated wastewater. The reactor has demonstrated a high degree of ability to accept large variations in feed rate and strength and still function efficiently. The work has produced the basis for a successful primary reactor design for the treatment of a problem wastewater and the necessary information on which a pilot scale plant could be designed for high suspended solids wastewaters. A possible method for the cultivation of granules in difficult wastewaters has been identified.Item Anaerobic filtration of waste waters arising from the production of bakers' yeast : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Biotechnology at Massey University(Massey University, 1984) Barnett, John WilliamA study was carried out to assess the effectiveness of the anaerobic filtration process in providing a relatively simple on-site waste pretreatment system for the wastes from the production of bakers' yeast. These are of a high strength and acidic nature. To maintain practical constraints on the project a real waste water was used. The waste water is low in suspended material, has a high organic matter concentration giving a COD of 70000 to 90000 mg/l (BOD5 14250 mg/l and a pH of 4.5 to 5.0. Two experimental anaerobic filter units were constructed of glass cylinders packed with glass 'Raschig' rings as the inert support matrix, and used in the trials. A statistically designed experimental programme was used to test the effects of inflent substrate concentration, hydraulic retention time, temperature and filter unit on the filter response variables. Substrate concentrations of 5500 to 47200 mg COD/l (1000 to 9000mg BOD5/l) and hydraulic retention times of 1 to 5 days were used which gave rise to organic loading rates of 1.15 to 47.2 kg COD/m3d (0.2 to 9.0 kg BOD5/m3d). Empirical models were derived from the response data, using multiple regression techniques, and describe COD removal rate, total gas production, methane production and conversion of COD to methane in terms of the independent process variables. Results showed that the anaerobic filter achieved COD removals of 34 to 65 percent with corresponding conversions of 24 to 78 percent efficiency to methane at loadings of up to 47.2 kg COD/m3d. The empirical equations were able to explain 92 to 97 percent of the observed variance. The system was stable over the entire range of applied conditions.Item The fate of methane in a New Zealand pulp and paper mill wastewater treatment system : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Environmental Technology & Sustainable Energy at Massey University, Palmerston North, New Zealand(Massey University, 2011) Manzano, John Mark LalunioThe wastewater produced by Carter Holt Harvey’s Kinleith pulp and paper mill in Tokoroa is currently treated by a series of aerobic ponds, designed to remove organic pollutants. The treatment system has experienced increases in Biological Oxygen Demand (BOD, a measure of organic pollution strength) at the outlet. The increases in BOD happened when no significant changes in wastewater influent flow and/or characteristics were recorded. The surge in BOD has caused the outlet discharge limit to be exceeded in the past. Based on previous studies, we believe that aerobic oxidation of methane (CH4), by microorganisms called methanotrophs, can cause the generation of methanol (a compound that can cause an increase in BOD load in waste streams), under conditions that repress the further conversion of methanol into biomass and carbon dioxide (CO2). The overall objectives of this project therefore were: ? To determine if the biosynthesis of CH4 can occur in the treatment system ? To determine if the subsequent biological aerobic CH4 oxidation to methanol can occur in the treatment system ? Whether enough methanol can be generated to affect the treatment system’s performance in terms of BOD removal. Evidence was found that confirmed CH4 was formed in the pond sediments across the entire treatment system (with rates significantly higher near the inlet). CH4 is therefore available in the treatment system for aerobic CH4 oxidation. The presence of aerobic conditions and the absence of dissolved CH4 in the water column (part of the pond where wastewater flows above the sediment), showed that aerobic CH4 oxidation can occur in the water column of the treatment system (except at the oxygen limited inlet). Laboratory testing also confirmed that aerobic CH4 oxidation can occur and methanotrophs are present (albeit in small numbers) in the water column. A model was used to determine if aerobic CH4 oxidation to methanol can cause the BOD increase at the outlet. The model found that the rates (CH4 production in the sediment and CH4 oxidation in the water column) needed to cause the surge in BOD was significantly higher than the maximum rates calculated from laboratory tests ofsamples collected from the treatment system. Aerobic CH4 oxidation was therefore unlikely to cause the BOD increase at the outlet. It is possible that the BOD increase is due to benthic feedback (anaerobic sludge layer becomes buoyant, suddenly releasing soluble compounds into the aerobic water column of a pond). The BOD increase experienced at the outlet followed similar characteristics associated with benthic feedback (event was random, occurred at a pond with an oxygen limited sludge layer and aerobic water column). If the cause of the BOD increase needs to be determined in the future, further investigation into benthic feedback is recommended. To conclude, aerobic CH4 oxidation to methanol can occur in the treatment system, but is unlikely to cause the BOD increase at the outlet of the treatment system. The technical capabilities and knowledge developed during the project will likely benefit those in the pulp mill industry. Methods and techniques have been developed to investigate the generation and fate of CH4 within a pulp mill aerated pond.Item Anaerobic co-digestion of municipal primary sludge and whey : a dissertation submitted in partial fulfilment of the requirements for the Masters degree in Environmental Engineering at Massey University, Palmerston North, New Zealand(Massey University, 2010) Zhang, XinyuanThe aim of this research was to investigate the feasibility of co-digestion of municipal primary sludge and whey by anaerobic CSTR (Continuous Stirred Tank Reactor), as well as the factors that affect the performance of the co-digestion reactors. Before studying the co-digestion process, a semi-continuous whey digestion experiment was conducted to analyze the feasibility of anaerobic digestion of whey along with pH control. The results obtained from the study indicated that supplement of nutrients, trace elements as well as heavy metals was necessary to maintain the anaerobic whey digestion system. To investigate the co-digestion of primary sludge and whey process, the effects of pH, OLR (Organic Loading Rate), HRT (Hydraulic retention time) as well as the COD (Chemical Oxygen Demand) loading ratio of primary sludge to whey on the performance of the reactors were studied. The results of the co-digestion experiments demonstrated that it was feasible to co-digest primary sludge and whey without nutrient, trace element and heavy metal supplement. The TCOD (Total Chemical Oxygen Demand) removal efficiency and the biogas production of the co-digestion system increased with the increase of OLR. At same OLR, digestion of the mixture of primary sludge and whey with higher whey content achieved higher biogas production and TCOD removal efficiency. The anaerobic co-digestion of primary sludge and whey process performed successfully at OLR of 5.8 ± 0.1g COD/l.d without pH control when the COD loading ratio of primary sludge to whey was approximately 70:30, due to the fact that the primary sludge may serve as buffering reagent. By adding sodium bicarbonate (NaHCO3) to maintain the pH at 6.9 ± 0.1, the OLR of the co-digestion reactor could reach 8.1 ± 0.1 g COD/l.d at HRT of 20 days. Moreover, by co-digestion of primary sludge and whey solution, the reactor could be operated successfully at HRT of 10 days and at OLR of 7.6 ± 0.1 g COD/l.d with COD loading ratio of primary sludge to whey of 53 : 47. The biogas production (3.2 ± 0.1 l/d) was 1.5 l/d higher than digestion of the same amount of primary sludge alone (1.7 ± 0.1 l/d).Item Biological phosphorus removal by microalgae in waste stabilisation ponds : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Environmental Engineering at Massey University, Palmerston North, New Zealand(Massey University, 2009) Powell, NicolaWaste stabilisation ponds (WSP) are an important wastewater treatment technology used by thousands of communities around the world. Unfortunately, phosphorus removal in WSP is generally low and inconsistent. The aim of this work was to investigate biological phosphorus removal by microalgae in WSP. Luxury uptake of phosphorus, which is the accumulation of polyphosphate, is known to occur in microalgae in natural systems such as lakes; however, this mechanism has not previously been studied under WSP conditions. Three methods were used in the laboratory to investigate luxury uptake and it was shown for the first time that luxury uptake of phosphorus can occur in microalgae under typical WSP conditions. Acid-insoluble polyphosphate (AISP) is a form of phosphorus storage and acid soluble polyphosphate (ASP) is used for synthesis of cellular constituents. However, the findings of this thesis indicate that ASP may also act as a form of short term storage. The environmental factors influencing luxury uptake were investigated using laboratory experiments conducted under controlled conditions. The key environmental factors were the phosphate concentration in the wastewater, light intensity and temperature. A higher phosphate concentration increased the amount of ASP accumulation and also resulted in AISP being stored within the cells instead of being consumed for growth. Higher light intensity increased ASP accumulation, but as a consequence of elevated growth, the ASP was rapidly consumed. Temperature influenced the rate of AISP accumulation and little if any was accumulated at low temperatures. The fate of polyphosphate in the sludge layer was also studied and it was shown that polyphosphate was degraded resulting in phosphate release. Therefore, to maximise phosphorus removal the microalgae needs to be harvested. Field work showed that at times the biomass contained almost four times the amount of phosphorus required for growth which confirms that luxury uptake does indeed occur in full-scale WSP. To improve phosphorus removal in WSP both luxury uptake and the biomass concentration need to be maximised simultaneously. With this new understanding of biological phosphorus removal in WSP and the key environmental factors required it may be possible to develop a new phosphorus removal process utilising luxury uptake by microalgae.