Massey Documents by Type

Permanent URI for this communityhttps://mro.massey.ac.nz/handle/10179/294

Browse

Has files: YesSubject: search.filters.subject.Sewage sludge

Search Results

Now showing 1 - 3 of 3
  • Thumbnail Image
    Item
    Measurement and control of odorous and polluting gases from wastes : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Soil Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2004) Kulasegarampillai, Manoharan
    Management of odorous and polluting gases from wastes is a world-wide challenge. Gaseous losses of nitrogen and sulphur from stored manure and sewage biosolids can be considerable, and these gaseous are offensive and undesirable. Hence, it is necessary to quantify these gas emissions from waste to determine the impact on air quality as well as to find out the efficient and effective control measures. A field observation indicated that amendment of dairy manure with natural materials, such as soil and wood shavings can reduce gaseous emission. To understand the mechanism for reduction of gaseous emissions and to select an optimum natural medium, laboratory incubation studies were conducted to measure the gaseous loss of ammonia (NH3 ) and hydrogen sulfide (H2 S) from stored manure and biosolids under aerobic and anaerobic conditions for a period of about 7 weeks. Natural materials such as soil, untreated pine bark, sawdust and wood savings, were evaluated for their potential to reduce these gaseous emissions. Ammonia emission rate was typically peak within two days of the experiment and declined rapidly under aerobic and anaerobic condition from stored manure and sewage biosolids. NH3 emission was higher during aerobic than anaerobic incubation but in the case of biosolids the difference was very small. The total nitrogen loss due to NH3 emission was very low. It was around 1.23% from manure and 1.87% from biosolids under aerobic incubation. Around 49 mg NH3 was emitted from a kg of cattle manure during aerobic incubation and it was 1155 mg from biosolids. H2 S emissions were higher during anaerobic than aerobic incubation from manure and biosolids. Around 9.2 mg H2 S was emitted from a kg of manure and it was around 150.7 mg from biosolids under anaerobic incubation. All materials tested were found to have an effect on the NH3 and H2 S emission. However, pine bark and top soil amendment reduced the emission efficiently. NH3 emission was reduced by 78% under anaerobic condition when 20g bark was amended with lOOg manure and it was around 56% in biosolids. Soil amendment reduced the NH3 emission by 50% in manure and 46% in biosolids. Pine bark reduced the H2 S emission by 80% from manure and by 83.5% from biosolids. Top soil amendment reduced the H2 S emission by 50% from manure and 79% from biosolids. Therefore, the addition of natural materials, such as pine bark and soil, as amendments to manure and biosolids during storage Offers potential for reducing emissions of NH3 and H2 S.
  • Thumbnail Image
    Item
    Casein whey as booster for anaerobic co-digestion of primary sludge : a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Environmental Engineering
    (Massey University, 2012) Güttler, Johanna
    Spare capacity found in many municipal primary sludge digesters could be used to improve the biogas production through the addition of other organic waste. This work investigates the potential of casein whey as an additional substrate. The amount of whey required for maximum biogas production and stable reactor performance was tested, along with the use of cow manure as an additional substrate to enhance reactor stability. Bench-scale continuously stirred tank reactors were operated at 38 °C with an initial hydraulic retention time of 20 days. Biogas production was recorded daily and compared to a control reactor. To assess reactor stability, pH, alkalinity, chemical oxygen demand (COD) and volatile fatty acid concentration were measured. To manage seasonal production, whey (W) was stored at ambient temperature prior to utilisation. This caused 74 % of the lactose to ferment to mainly L-lactate, accompanied by a pH drop from initially 4.5 to 3.6 and decreased COD. While fresh whey co-digested with primary sludge (PS) did not improve the biogas production, stored whey utilised at the ratio 10:3 (PS:W) improved the biogas production to 150 % of the control. Cow manure (CM) co-digested with primary sludge and fresh whey at the ratio 10:7:1 (PS:W:CM) improved the biogas production by up to 200 % after slow acclimatisation to the whey. The addition of cow manure to primary sludge and stored whey did not improve the biogas production beyond the 150 % achieved without cow manure. Investigation into why cow manure improved biogas production in primary sludge and whey co-digestion established that fungi found in cow manure could play an important role in the hydrolysis of complex material and therefore the biogas production. Improved biogas production from fresh whey was only achieved when cow manure was provided. It appeared that additional lactic acid bacteria supplied by cow manure was required to ferment the high lactose concentration in fresh whey. This work has shown how the seasonal availability of whey can be effectively used to improve the biogas production from municipal sludge digestion. During peak milk production fresh whey could be co-digested with primary sludge and cow manure at the ratio 10:5:1 (PS:W:CM) achieving 178 % biogas production. If cow manure is difficult to obtain, the ratio 10:3:0.1 is recommended, achieving 138 % biogas production. When the availability of fresh whey decreases, stored whey at the ratio 10:3 (PS:W) is recommended without cow manure, producing 150 % biogas compared to primary sludge alone. Utilising whey as a viable substrate would improve productivity of municipal sludge digesters as well as alleviating environmental issues associated with whey disposal.
  • Thumbnail Image
    Item
    Copper and zinc dynamics and bioavailability in soils amended with biosolids : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Soil Science at Massey University, Palmerston North, New Zealand
    (Massey University, 2010) Jeyakumar, Paramsothy
    Global sewage sludge (biosolids) production is increasing as a result of rapidly growing human population and ensuing industrial activities. Land application of this waste is becoming a serious environmental issue because the high levels of heavy metals in biosolids can upset soil microbial activity and nutrient balance when the waste is added to forest or agricultural lands. It is widely accepted that bioavailability, rather than total soil concentration, is more important when assessing the risk associated with metal contamination. The bioavailability of a heavy metal is dependent on the chemical nature of the metal, the chemical, physical and biological properties of biosolids that contain the metal and of soil that receives the biosolids. It also depends on the interaction of the biosolids with soil, plants and soil microorganisms. The overall aim of this thesis was to assess the bioavailability of biosolids–derived Cu and Zn and the comparative effects of these metals on plant and soil microbial activity, with special attention to mycorrhiza, and the effects of application of lime and Al dross as ameliorants for the reduction of bioavailability of these two metals. Biosolids were collected from the Palmerston North City Council Waste Water Treatment Plant (PNCCWTP) sludge lagoon in Palmerston North, New Zealand. Because the metal concentrations were low, for research purposes these biosolids were spiked separately with three levels of Cu (to give final concentrations of 50, 150 and 250 mg/kg soil) and Zn (to give final concentrations of 150, 450 and 750 mg/kg soil) added as metal sulphate salts. The biosolids were anaerobically incubated, and it was found that a shorter period of equilibration (2 months) than the previously used 6–9 months was sufficient for Cu and Zn to be fully incorporated into the biosolids matrix. As biosolids in New Zealand are currently applied to forest lands, two important forest plants, poplar and pine, were considered for the study in this thesis. The effects of elevated concentrations of Cu and Zn in a soil amended with metal spiked biosolids on poplar plants were investigated in a 147 day glasshouse pot trial. The findings of this trial showed that at the same total soil metal concentration, biosolids–derived Cu was more toxic than Zn to soil microorganisms, whereas Zn was more toxic to poplar and ECM fungi. In a similar glasshouse study lasting 312 days with pine, Cu did not show a phytotoxic effect, but Zn was phytotoxic to pine. However, both metals were toxic to microorganisms and neither metal influenced ECM fungi colony development. The currently recommended maximum metal concentration limits for New Zealand soils of 100 mg/kg for Cu and 300 mg/kg for Zn appear to be high for both metals with respect to soil microbial activity, but low for Cu and high for Zn with respect to poplar and pine growth. A laboratory incubation trial with Cu– and Zn– spiked biosolids added to eight soils representing the major Soil Groups collected from across the North Island of New Zealand (biosolids added to give final soil concentrations of 150 mg/kg for Zn or 450 mg/kg for Cu), showed that crystalline Fe oxide was the dominant factor explaining 90% of the variability in exchangeable Cu. For Zn, clay content and pH were the controlling soil factors that together explained 73% of the variability in exchangeable Zn. An increased content of crystalline Fe oxide increased the soil exchangeable Cu concentration. Decreasing pH and increasing clay content increased the soil exchangeable Zn concentration. The effect of lime (0.1 and 0.5%), Al dross (2 and 6%) and a combination of lime and Al dross (0.1% lime+2% Al dross) as soil amendments for the amelioration of the toxic effect of biosolids–derived Cu (144 mg/kg in soil) and Zn (417 mg/kg in soil) on microorganisms and poplar were also studied. Results revealed that application of lime and Al dross (pH 10) as a mixture (0.1% lime+2% Al dross) was able to ameliorate Cu and Zn phytotoxicity, and significantly increase the DM yield of poplar, ECM fungi population and microbial activity in the Cu and Zn contaminated soils. The findings of the studies in this thesis are applicable to environmental regulations with respect to heavy metal limits that seek to protect agricultural and forest land, human and animal health, and soil and drinking water quality, in scenarios where biosolids are applied to soil.