scholarly journals Development of a deterministic design model for a high-rate algal pond

Water SA ◽  
2018 ◽  
Vol 44 (4 October) ◽  
Author(s):  
ISW Van der Merwe ◽  
IC Brink
Keyword(s):  
South Africa ◽  
Wastewater Treatment ◽  
Deterministic Model ◽  
Design Model ◽  
High Rate ◽  
Nitrogen And Phosphorus ◽  
Treated Effluent ◽  
Attractive Option ◽  
Mutualistic Relationship ◽  
Treatment Facilities

Inadequate wastewater treatment is a major problem in South Africa. Existing wastewater treatment facilities often lack sufficient skilled labour, resulting in partially treated effluent. Increasing eutrophication in surface water bodies indicates that this problem needs rectification. The characteristics of the high-rate algal pond (HRAP) technology makes it an attractive option for effluent polishing in South Africa. It has the potential of simultaneous nutrient removal and nutrient recovery from partially treated effluent. A deterministic design model based on the mutualistic relationship between bacteria and algae in an HRAP was developed. The model includes kinetics of algae, ordinary heterotrophic organisms (OHOs), as well as ammoniaoxidising organisms (ANOs) and their interaction with organic compounds, nitrogen and phosphorus. After preliminary verifications, it was found that the deterministic model accurately represented the kinetics involved with the ammonia and nitrate/nitrite concentrations. However, it was also established that the major limitations of the deterministic model are its exclusion of phosphate precipitation and its failure to incorporate the production of particulate and soluble organics due to the respiration, excretion and mortality processes.

Determination of Nitrogen and Phosphorus Partitioning within Components of the Biomass in a High Rate Algal Pond: Significance for the Coastal Environment of the Treated Effluent Discharge

1992 ◽  
Vol 25 (12) ◽  
pp. 207-214 ◽  
Author(s):  
N. J. Cromar ◽  
N. J. Martin ◽  
N. Christofi ◽  
P. A. Read ◽  
H. J. Fallowfield
Keyword(s):  
Dry Matter ◽  
Coastal Environment ◽  
High Rate ◽  
Nutrient Input ◽  
Nitrogen And Phosphorus ◽  
Loading Rates ◽  
Effective Strategies ◽  
Treated Effluent ◽  
Algae And Bacteria

Two High-Rate Algal Ponds were operated over residence times of 4 and 6 days respectively, at three COD loading rates equivalent to 600, 350 and 100 kg ha−1d−1 from early September to late October 1991. Samples of pond N and P feed were analysed to obtain nutrient input values to the system. Pond filtrates were also analysed for soluble nutrients. The pond biomass was separated into constituent components of algae and bacteria. Following separation, the discrete fractions were analysed for dry matter, chlorophyll content, and paniculate carbon, hydrogen, nitrogen and phosphorus. Nitrogen and phosphorus balances were then calculated which were used to partition the nutrients into soluble and paniculate phases, and to further separate the paniculate phase into algal and bacterial components. The partitioning of these nutrients, responsible for eutrophication, enables the calculation of removal rates of N and P from the pond systems and makes possible more effective strategies for the removal of the nutrient-rich biomass from receiving water bodies.

Evolution of the Southpest Wastewater Treatment Plant

2000 ◽  
Vol 41 (9) ◽  
pp. 7-14
Author(s):  
A. Jobbágy ◽  
B. Literáthy ◽  
F. Farkas ◽  
Gy. Garai ◽  
Gy. Kovács
Keyword(s):  
Wastewater Treatment ◽  
Activated Sludge ◽  
Wastewater Treatment Plant ◽  
Phosphorus Removal ◽  
Treatment Plant ◽  
Low Flow ◽  
Nitrate Content ◽  
Nitrogen And Phosphorus ◽  
Treated Effluent ◽  
Processing Wastes

The treated effluent of the Southpest Wastewater Treatment Plant is discharged into a small, low-flow branch of the Danube susceptible to eutrophication. The first, high-load activated sludge system with a hydraulic retention time of 2.5 hrs in the aerated basins, was installed here in 1966. The paper presents the evolution of the technology by illustrating the effects of the different changes carried out since 1991. Reconfiguration of the existing activated sludge basins connected originally in parallel into an arrangement of tanks in series increased the settleability of the sludge as well as the efficiency of COD removal significantly. Introduction of an anaerobic zone preceding the aerated basins facilitated biological excess phosphorus removal with a consequent release in the thickener and digester. Introducing lime addition into the recycled sludge processing wastes significantly improved the performance of the system. However, since there had been no provision built for eliminating the nitrate content of the recycled sludge, efficiency of phosphorus removal proved to be dependent on the eventually occurring nitrification. In order to achieve both an effective nitrogen and phosphorus removal the current technology established in 1999 applies a nitrification and a denitrification filter following the activated sludge unit and uses precipitation for phosphorus removal.

scholarly journals Nitrous oxide emissions during microalgae-based wastewater treatment: current state of the art and implication for greenhouse gases budgeting

2020 ◽  
Vol 82 (6) ◽  
pp. 1025-1030
Author(s):  
Maxence Plouviez ◽  
Benoit Guieysse
Keyword(s):  
Nitrous Oxide ◽  
Wastewater Treatment ◽  
Mitigation Strategies ◽  
High Rate ◽  
Nitrous Oxide Emissions ◽  
Future Research ◽  
N2o Emissions ◽  
Nitrogen And Phosphorus ◽  
Intergovernmental Panel ◽  
Aerobic Wastewater Treatment

Abstract Microalgae can synthesise the ozone depleting pollutant and greenhouse gas nitrous oxide (N2O). Consequently, significant N2O emissions have been recorded during real wastewater treatment in high rate algal ponds (HRAPs). While data scarcity and variability prevent meaningful assessment, the magnitude reported (0.13–0.57% of the influent nitrogen load) is within the range reported by the Intergovernmental Panel on Climate Change (IPCC) for direct N2O emissions during centralised aerobic wastewater treatment (0.016–4.5% of the influent nitrogen load). Critically, the ability of microalgae to synthesise N2O challenges the IPCC's broad view that bacterial denitrification and nitrification are the only major cause of N2O emissions from wastewater plants and aquatic environments receiving nitrogen from wastewater effluents. Significant N2O emissions have indeed been repeatedly detected from eutrophic water bodies and wastewater discharge contributes to eutrophication via the release of nitrogen and phosphorus. Considering the complex interplays between nitrogen and phosphorus supply, microalgal growth, and microalgal N2O synthesis, further research must urgently seek to better quantify N2O emissions from microalgae-based wastewater systems and eutrophic ecosystems receiving wastewater. This future research will ultimately improve the prediction of N2O emissions from wastewater treatment in national inventories and may therefore affect the prioritisation of mitigation strategies.

Using wastewater and high-rate algal ponds for nutrient removal and the production of bioenergy and biofuels

2013 ◽  
Vol 67 (4) ◽  
pp. 915-924 ◽  
Author(s):  
David Batten ◽  
Tom Beer ◽  
George Freischmidt ◽  
Tim Grant ◽  
Kurt Liffman ◽  
...  
Keyword(s):  
Wastewater Treatment ◽  
Nutrient Removal ◽  
Large Scale ◽  
Oxygen Demand ◽  
Recent Change ◽  
High Rate ◽  
Coastal Zones ◽  
Nitrogen And Phosphorus ◽  
Treatment Technology ◽  
Algae Biomass

This paper projects a positive outcome for large-scale algal biofuel and energy production when wastewater treatment is the primary goal. Such a view arises partly from a recent change in emphasis in wastewater treatment technology, from simply oxidising the organic matter in the waste (i.e. removing the biological oxygen demand) to removing the nutrients – specifically nitrogen and phosphorus – which are the root cause of eutrophication of inland waterways and coastal zones. A growing need for nutrient removal greatly improves the prospects for using new algal ponds in wastewater treatment, since microalgae are particularly efficient in capturing and removing such nutrients. Using a spreadsheet model, four scenarios combining algae biomass production with the making of biodiesel, biogas and other products were assessed for two of Australia’s largest wastewater treatment plants. The results showed that super critical water reactors and anaerobic digesters could be attractive pathway options, the latter providing significant savings in greenhouse gas emissions. Combining anaerobic digestion with oil extraction and the internal economies derived from cheap land and recycling of water and nutrients on-site could allow algal oil to be produced for less than US$1 per litre.

Wastewater Treatment for a Sustainable Future: Overview of Phosphorus Recovery

2011 ◽  
Vol 110-116 ◽  
pp. 2043-2048 ◽  
Author(s):  
S. Muryanto ◽  
A.P. Bayuseno
Keyword(s):  
Wastewater Treatment ◽  
Natural Waters ◽  
Treatment Options ◽  
Chemical Precipitation ◽  
Phosphorus Recovery ◽  
Biological Uptake ◽  
Attractive Option ◽  
Treatment Facilities ◽  
Crystallisation Process ◽  
Removal And Recovery

Intensified agriculture in response to the growing population has led to excessive nutrient discharges to natural waters causing environmental problems in the form of eutrophication and its associated risks. Treatment options for this adverse effect include removal and recovery of soluble phosphorus by chemical precipitation, biological uptake, and struvite crystallisation. Chemical precipitation is the most common method due to its simplicity, but the chemical requirements can be prohibitive and the removed phosphorus is less reusable. Biological uptake requires less chemicals but the process is complex and prone to seasonal variations. Phosphorus removal and recovery from wastewater by struvite crystallisation is an attractive option since the crystallisation process converts phosphorus into struvite crystals, i.e. phosphate minerals which have proved to be good fertilizer, hence potentially reduces fertilizer production and the subsequent greenhouse gas emissions. Moreover, struvite crystallisation helps prevent scaling of wastewater treatment facilities. A number of struvite crystallisation projects utilising primarily agricultural wastewater is already operational at industrial scale.

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