Comprehensive Oilgae Report

A detailed report on all aspects of the algae fuel value chain, the Comprehensive Oilgae Report will be of immense help to those who are on the threshold of investing in algae biofuels. More ››

Algae-based Wastewater Treatment

Compiled by a diverse team of experts, with experience in scientific and industrial fields, the Comprehensive Report for Wastewater Treatment Using Algae is the first report that provides in-depth analysis and insights on this important field. It uses innumerable data and information from a wide variety of expert sources and market studies, and distills these inputs and data into intelligence and a roadmap that you can use. More ››

Comprehensive Guide for Algae-based Carbon Capture

A Comprehensive Guide for Entrepreneurs and Businesses Who Wish to get a Basic Understanding of the Business Opportunities and Industry Dynamics of the Algae-based CO2. More ››


Comprehensive Report on Attractive Algae Product Opportunities

This is for entrepreneurs and businesses who wish to get a basic understanding of the algae fuel business and industrThe report provides an overview of the wide range of non-fuel applications of algae – both current and future prospects. It will provide entrepreneurs with an idea of how to derive more benefits from their algal energy ventures. The report provides detailed case studies, success stories and factoids of companies that have been involved in the algae products venture. More ››

Comprehensive Castor Oil Report

There is no other comprehensive report available for castor oil anywhere in the world. This is the first of its kind, and currently, the only one. More ››

Bioplastics Market & Strategy Advisor

Bioplastics Market & Strategy Advisor, published by the Bioplastics Guide, is a unique guiding framework for businesses and entrepreneurs to chart a way forward provides a critical analysis of the status, opportunities & trends of the global bioplastics sector. More ››

Algae - Food and Feed

Edible Sea-weeds 

Hydrocolloids

Animal and Fish Feed

Algae-Useful Substances

Pigments

PUFAs

Vitamins

Anti-oxidants


Algae for Pollution Control

Other Novel Applications

New Technologies in Phosphorous Removal from Wastewater


Clean Water the Clean Way

One product is the solution for problems over the decades in wastewater treatment, fish kills, dead zone, aquatic food chain, aquaculture, agriculture...

Nualgi facilitates the growth of diatoms. It prevents the growth of waterweeds, water hyacinth, Green algae and blue-green algae and other waste plants in lakes, ponds, rivers and other water bodies. Other algae like blue Green algae disrupt the ecosystem in water.

Wish to know more?...read more

Contact: Vinayak Bhanu

Mobile 0091 9840441078

Email vinayak@clixoo.com

Phosphorus (P) occurs in natural waters and in wastewaters almost solely as phosphates. These phosphates include organic phosphate, polyphosphate (particulate P) and orthophosphate (inorganic P). Orthophosphates are readily utilized by aquatic organisms. Some organisms may store excess phosphorus in the form of polyphosphates for future use. At the same time, some phosphate is continually lost in the sediments where it is locked up in insoluble precipitates.

Normally secondary treatment can only remove 1-2 mg/l, so a large excess of phosphorous is discharged in the final effluent, causing eutrophication in surface waters. New legislation requires a maximum concentration of P discharges into sensitive water of 2 mg/l.

This section provides details on the latest developments and efforts in the removal of phosphorus from wastewater.

We have discussed the following:

  • Current Wastewater Treatment Process – Phosphorus Removal
  • New Technologies in the Removal of Phosphorus from Waste Water
    • Calcium-Sequestered Phosphate Removal
    • Magnetic Separation
    • Adsorption
    • A Review and Update of the Microbiology of Enhanced Biological Phosphorus Removal in Wastewater Treatment Plants
    • Nitrification, Denitrification and Biological Phosphorus Removal in Piggery Wastewater Using A Sequencing Batch Reactor
    • Removal of Phosphorus and Organic Matter Removal by Alum During Wastewater Treatment
    • Microbial Selection of Polyphosphate-Accumulating Bacteria in Activated Sludge Wastewater Treatment Processes for Enhanced Biological Phosphate Removal

Current Wastewater Treatment Process

Phosphate removal is currently achieved largely by chemical precipitation, which is expensive and causes an increase of sludge volume by up to 40%. An alternative is the biological phosphate removal (BPR).

Chemical Precipitation

The main phosphate removal processes are:

1.Treatment of raw/primary wastewater

2.Treatment of final effluent of biological plants (postprecipitation)

3.Treatment contemporary to the secondary biologic reaction (co-precipitation).

Processes of Phosphate Removal from Wastewater

Apart from these processes, phosphorus present in wastewater streams can also be removed by the electroplating technique.

The iron plates are connected to external power supply and are dipped in the wastewater taken in a suitable container. The phosphorus present in the wastewater will be eliminated as ferrous phosphate (with the iron plates and the oxygen in the water) and can thus be removed from the stream. Phosphate removal by chemical precipitation is expensive and causes an increase of sludge volume by up to 40%.

Source: http://www.apec-vc.or.jp/e/modules/tinyd00/index.php?id=44&kh_open_cid_00=10

Biological Phosphate Removal (BPR)

In the biological removal of phosphorous, the phosphorous in the influent wastewater is incorporated into cell biomass, which is subsequently removed from the process as a result of sludge wasting. The reactor configuration provides the P accumulating organisms (PAO) with a competitive advantage over other bacteria. So PAO are encouraged to grow and consume phosphorous. The reactor configuration in comprised of an anaerobic tank and an activated sludge activated tank. The retention time in the anaerobic tank is about 0.50 to 1.00 hours and its contents are mixed to provide contact with the return activated sludge and influent wastewater.

Process

In the anaerobic zone

Under anaerobic conditions, PAO assimilate fermentation products (i.e. volatile fatty acids) into storage products within the cells with the concomitant release of phosphorous from stored polyphosphates. Acetate is produced by fermentation of bsCOD, which is dissolved degradable organic material that can be easily assimilated by the biomass. Using energy available from stored polyphosphates, the PAO assimilate acetate and produce intracellular polyhydroxybutyrate (PHB) storage products. Concurrent with the acetate uptake is the release of orthophosphates, as well as magnesium, potassium, calcium cations. The PHB content in the PAO increases as the polyphosphate decreases.

In the aerobic zone

In the aerobic zone energy is produced by the oxidation of storage products and polyphosphate storage within the cell increases. Stored PHB is metabolized, providing energy from oxidation and carbon for new cell growth. Some glycogen is produced from PHB metabolism. The energy released from PHB oxidation is used to form polyphosphate bonds in cell storage. The soluble orthophosphate is removed from solution and incorporated into polyphosphates within the bacterial cell. PHB utilisation also enhances cell growth and this new biomass with high polyphosphate storage accounts for phosphorous removal. As a portion of the biomass is wasted, the stored phosphorous is removed from the biotreatment reactor for ultimate disposal with the waste sludge.

The amount of phosphorous removed by biological storage can be estimated from the amount of bsCOD that is available in the wastewater influent. Better performance for BPR systems is achieved when bsCOD acetate is available at a steady rate.

Advantages

  • reduced chemical costs
  • Less sludge production as compared to chemical precipitation.


New Technologies in the Removal of Phosphorus from Waste Water

Calcium-Sequestered Phosphate Removal

This method for recovering phosphate comprises of:

 Obtaining an effluent (wastewater) having calcium-sequestered phosphate;

  1. Adding to the effluent or wastewater a calcium chelating or sequestration agent suitable to chelate or sequester Ca++ ions from the calcium-sequestered phosphate to facilitate release of phosphate from the calcium-sequestered phosphate;
  2. Transferring, facilitated by said Ca++ ion capture and in the presence of sufficient concentrations of NH4+ and Mgions, of the phosphate into struvite (magnesium ammonium phosphate hexahydrate or MgNH4PO4.6H2O), or hydrated magnesium ammonium complex of phosphate;
  3. Recovering the struvite, or the formed hydrated magnesium ammonium complex.
  4. The method further comprises acidification of the effluent or wastewater to facilitate release of Ca++ ions from the calcium-sequestered phosphate and chelation of sequestration of the Ca++ ions by the calcium chelating or sequestration agent.
  5. Additional aspects provide a phosphate-containing fertilizer comprising struvite, and methods for making same.2

Magnetic Separation

The main principle of magnetic method is separation of particles being removed with the use of magnetic field. So this method can be applied for particulate impurities. To remove phosphorus one must convert it into insoluble form for example in the way of primary sedimentation. Besides these particles must posses magnetic properties while such properties are not common among wastewater constituents. To strengthen magnetic properties so called magnetic carriers are added, usually magnetite (Fe3O4).

Great advantages of this process are:

  • high elimination performance,
  • compact process
  • Low power input.

Adsorption

The adsorptive capacity for phosphates were greatest where adsorbents were used without any treatment. Another concept was a phosphorus removal by orthophosphate nucleation and use of phosphate rock in a packed column system seemed to be an applicable technology as a ‘polishing’ process after a lime treatment. Over 80% efficiency was reached with the use of aluminium oxide (Wiess 1992). In the Netherlands wetlands have been applied for polishing the effluent from trickling filters. Its disadvantage is that P is stored in wetland organisms mostly in roots and in dead matter and only 7% of it appear to be removable by harvesting.

A Review and Update of the Microbiology of Enhanced Biological Phosphorus Removal in Wastewater Treatment Plants

Enhanced biological phosphorus removal (EBPR) from wastewater can be more-or-less practically achieved but the microbiological and biochemical components are not completely understood. EBPR involves cycling microbial biomass and influent wastewater through anaerobic and aerobic zones to achieve a selection of microorganisms with high capacity to accumulate polyphosphate intracellularly in the aerobic period. Biochemical or metabolic modelling of the process has been used to explain the types of carbon and phosphorus transformations in sludge biomass. There are essentially two broad-groupings of microorganisms involved in EBPR. They are polyphosphate accumulating organisms (PAOs) and their supposed carbon-competitors called glycogen accumulating organisms (GAOs). The morphological appearance of microorganisms in EBPR sludges has attracted attention. For example, GAOs as tetrad-arranged cocci and clusters of coccobacillus-shaped PAOs have been much commented upon and the use of simple cellular staining methods has contributed to EBPR knowledge. Acinetobacter and other bacteria were regularly isolated in pure culture from EBPR sludges and were initially thought to be PAOs. However, when contemporary molecular microbial ecology methods in concert with detailed process performance data and simple intracellular polymer staining methods were used, a betaproteobacteria called ‘Candidatus Accumulibacter phosphatis’ was confirmed as a PAO and organisms from a novel gammaproteobacteria lineage were GAOs. To preclude making the mistakes of previous researchers, it is recommended that the sludge ‘biography’ be well understood – i.e. details of phenotype (process performance and biochemistry) and microbial community structure should be linked.3

Nitrification, Denitrification and Biological Phosphorus Removal in Piggery Wastewater Using a Sequencing Batch Reactor

Nutrients in piggery wastewater with high organic matter, nitrogen (N) and phosphorus (P) content were biologically removed in a sequencing batch reactor (SBR) with anaerobic, aerobic and anoxic stages. The SBR was operated with 3 cycles/day, temperature 30 °C, sludge retention time (SRT) 1 day and hydraulic retention time (HRT) 11 days. With a wastewater containing 1500 mg/l ammonium and 144 mg/l phosphate, a removal efficiency of 99.7% for nitrogen and 97.3% for phosphate was obtained. Experiments set up to evaluate the effect of temperature on the process showed that it should be run at temperatures higher than 16 °C to obtain good removals (>95%). Batch tests (ammonia utilization rate, nitrogen utilization rate and oxygen utilization rate) proved to be good tools to evaluate heterotrophic and autotrophic biomass activity. The SBR proved to be a very flexible tool, and was particularly suitable for the treatment of piggery wastewater, characterized by high nutrient content and by frequent changes in composition and therefore affecting process conditions.4

Removal of Phosphorus and Organic Matter Removal by Alum during Wastewater Treatment

Ferron reagent and FTIR spectroscopy were used for the identification and characterization of the aluminum species formed during dephosphorization of simulated wastewater with and without organic matter. Evidence from FTIR spectroscopy showed the formation of aluminum hydroxyphosphate, hydroxy-Al–tannate and aluminum complexes containing both phosphorus and tannic acid. The surface reactivity of the solid products is proportional to the rate of reaction with ferron. The measured reactivities indicate that aluminum solid species with different surface properties were formed depending on solution components and method of precipitation. Tannic acid was found to inhibit phosphorus removal and the extent of inhibition increased with increasing concentration. When prehydrolyzed aluminum is exposed to tannic acid, the organic matter forms a coating on the surface of the inorganic solid during the aging process. Coprecipitation of aluminum, phosphate and tannic acid, which is synonymous with the addition of alum before or in the aerator, produces some soluble complex and some hydroxy-Al–phosphate–tannate complex, in the form of solid with very small particle size. This system gives high residual aluminum. The results suggest that it is advantageous to add at least a portion of the alum at the exit of the aerator. This enhances phosphorus removal by coprecipitation under conditions where the concentration of organic matter is relatively low and enhances removal of organic matter by postprecipitation onto the recycled sludge in the aerator.5

Microbial Selection of Polyphosphate-Accumulating Bacteria in Activated Sludge Wastewater Treatment Processes for Enhanced Biological Phosphate Removal

Activated sludge processes with alternating anaerobic and aerobic conditions (the anaerobic.aerobic process) have been successfully used for enhanced biological phosphate removal (EBPR) from wastewater. It is known that polyphosphate-accumulating bacteria (PAB) play an essential role for EBPR in the anaerobic.aerobic process. The present paper reviews limited information available on the metabolism and the microbial community structure of EBPR, highlighting the microbial ecological selection of PAB in EBPR processes. Exposure of microorganisms to alternate carbon- rich anaerobic environments and carbon-poor aerobic environments in the anaerobic.aerobic process induces the key metabolic characteristics of PAB, which include organic substrate uptake followed by its conversion to stored polyhydroxyalkanoate (PHA) and hydrolysis of intracellular polyphosphate accompanied by subsequent Pi release under anaerobic conditions. Intracellular glycogen is assumed to function as a regulator of the redox balance in the cell. Storage of glycogen is a key strategy for PAB to maintain the redox balance in the anaerobic uptake of various organic substrates, and hence to win in the microbial selection. Acinetobacter spp., Microlunatus phosphovorus, Lampropedia spp., and the Rhodocyclus group have been reported as candidates of PAB. PAB may not be composed of a few limited genospecies, but involve phylogenetically and taxonomically diverse groups of bacteria. To define microbial community structure of EBPR processes, it is needed to look more closely into the occurrence and behavior of each species of PAB in various EBPR processes mainly by molecular methods because many of PAB seem to be impossible to culture.6

References

1http://www.lenntech.com/phosphorous-removal.htm

2Zhang, Tianxi, Bowers, Keith E., Harrison, Joseph H., Chen, Shulin, 2009. Patent: Compositions And Methods For Wastewater Treatment.

3Linda L. Blackall, Gregory R. Crocetti, Aaron M. Saunders and Philip L. Bond, 2002. A review and update of the microbiology of enhanced biological phosphorus removal in wastewater treatment plants. Antonie van Leeuwenhoek, 81 ( 681- 691).

4D. Obaja, S. Macé, J. Costa, C. Sans and J. Mata-Alvarez, 2003. Nitrification, denitrification and biological phosphorus removal in piggery wastewater using a sequencing batch reactor. Biosource Technology, 87 (103- 111).

5OmoikeA. I and vanLoon, G. W, 1999. Removal of phosphorus and organic matter removal by alum during wastewater treatment. Water Research, 33 ( 3617- 3627).

6Mino T, 2000.  Microbial Selection of Polyphosphate-Accumulating Bacteria in Activated Sludge Wastewater Treatment Processes for Enhanced Biological Phosphate Removal. Biochemistry, 65 (341- 348). 

Phosphorus (P) occurs in natural waters and in wastewaters almost solely as phosphates. These phosphates include organic phosphate, polyphosphate (particulate P) and orthophosphate (inorganic P). Orthophosphates are readily utilized by aquatic organisms. Some organisms may store excess phosphorus in the form of polyphosphates for future use. At the same time, some phosphate is continually lost in the sediments where it is locked up in insoluble precipitates.

Normally secondary treatment can only remove 1-2 mg/l, so a large excess of phosphorous is discharged in the final effluent, causing eutrophication in surface waters. New legislation requires a maximum concentration of P discharges into sensitive water of 2 mg/l.

This section provides details on the latest developments and efforts in the removal of phosphorus from wastewater.

We have discussed the following:

  • Current Wastewater Treatment Process – Phosphorus Removal
  • New Technologies in the Removal of Phosphorus from Waste Water
    • Calcium-Sequestered Phosphate Removal
    • Magnetic Separation
    • Adsorption
    • A Review and Update of the Microbiology of Enhanced Biological Phosphorus Removal in Wastewater Treatment Plants
    • Nitrification, Denitrification and Biological Phosphorus Removal in Piggery Wastewater Using A Sequencing Batch Reactor
    • Removal of Phosphorus and Organic Matter Removal by Alum During Wastewater Treatment
    • Microbial Selection of Polyphosphate-Accumulating Bacteria in Activated Sludge Wastewater Treatment Processes for Enhanced Biological Phosphate Removal

Current Wastewater Treatment Process

Phosphate removal is currently achieved largely by chemical precipitation, which is expensive and causes an increase of sludge volume by up to 40%. An alternative is the biological phosphate removal (BPR).

Chemical Precipitation

The main phosphate removal processes are:

1.Treatment of raw/primary wastewater

2.Treatment of final effluent of biological plants (postprecipitation)

3.Treatment contemporary to the secondary biologic reaction (co-precipitation).

Processes of Phosphate Removal from Wastewater

Apart from these processes, phosphorus present in wastewater streams can also be removed by the electroplating technique.

The iron plates are connected to external power supply and are dipped in the wastewater taken in a suitable container. The phosphorus present in the wastewater will be eliminated as ferrous phosphate (with the iron plates and the oxygen in the water) and can thus be removed from the stream. Phosphate removal by chemical precipitation is expensive and causes an increase of sludge volume by up to 40%.

Source: http://www.apec-vc.or.jp/e/modules/tinyd00/index.php?id=44&kh_open_cid_00=10

Biological Phosphate Removal (BPR)

In the biological removal of phosphorous, the phosphorous in the influent wastewater is incorporated into cell biomass, which is subsequently removed from the process as a result of sludge wasting. The reactor configuration provides the P accumulating organisms (PAO) with a competitive advantage over other bacteria. So PAO are encouraged to grow and consume phosphorous. The reactor configuration in comprised of an anaerobic tank and an activated sludge activated tank. The retention time in the anaerobic tank is about 0.50 to 1.00 hours and its contents are mixed to provide contact with the return activated sludge and influent wastewater.

Process

In the anaerobic zone

Under anaerobic conditions, PAO assimilate Fermentation products (i.e. volatile fatty acids) into storage products within the cells with the concomitant release of phosphorous from stored polyphosphates. Acetate is produced by fermentation of bsCOD, which is dissolved degradable organic material that can be easily assimilated by the biomass. Using energy available from stored polyphosphates, the PAO assimilate acetate and produce intracellular polyhydroxybutyrate (PHB) storage products. Concurrent with the acetate uptake is the release of orthophosphates, as well as magnesium, potassium, calcium cations. The PHB content in the PAO increases as the polyphosphate decreases.

In the aerobic zone

In the aerobic zone energy is produced by the oxidation of storage products and polyphosphate storage within the cell increases. Stored PHB is metabolized, providing energy from oxidation and carbon for new cell growth. Some glycogen is produced from PHB metabolism. The energy released from PHB oxidation is used to form polyphosphate bonds in cell storage. The soluble orthophosphate is removed from solution and incorporated into polyphosphates within the bacterial cell. PHB utilisation also enhances cell growth and this new biomass with high polyphosphate storage accounts for phosphorous removal. As a portion of the biomass is wasted, the stored phosphorous is removed from the biotreatment reactor for ultimate disposal with the waste sludge.

The amount of phosphorous removed by biological storage can be estimated from the amount of bsCOD that is available in the wastewater influent. Better performance for BPR systems is achieved when bsCOD acetate is available at a steady rate.

Advantages

  • reduced chemical costs
  • Less sludge production as compared to chemical precipitation.


New Technologies in the Removal of Phosphorus from Waste Water

Calcium-Sequestered Phosphate Removal

This method for recovering phosphate comprises of:

 Obtaining an effluent (wastewater) having calcium-sequestered phosphate;

  1. Adding to the effluent or wastewater a calcium chelating or sequestration agent suitable to chelate or sequester Ca++ ions from the calcium-sequestered phosphate to facilitate release of phosphate from the calcium-sequestered phosphate;
  2. Transferring, facilitated by said Ca++ ion capture and in the presence of sufficient concentrations of NH4+ and Mgions, of the phosphate into struvite (magnesium ammonium phosphate hexahydrate or MgNH4PO4.6H2O), or hydrated magnesium ammonium complex of phosphate;
  3. Recovering the struvite, or the formed hydrated magnesium ammonium complex.
  4. The method further comprises acidification of the effluent or wastewater to facilitate release of Ca++ ions from the calcium-sequestered phosphate and chelation of sequestration of the Ca++ ions by the calcium chelating or sequestration agent.
  5. Additional aspects provide a phosphate-containing fertilizer comprising struvite, and methods for making same.2

Magnetic Separation

The main principle of magnetic method is separation of particles being removed with the use of magnetic field. So this method can be applied for particulate impurities. To remove phosphorus one must convert it into insoluble form for example in the way of primary sedimentation. Besides these particles must posses magnetic properties while such properties are not common among wastewater constituents. To strengthen magnetic properties so called magnetic carriers are added, usually magnetite (Fe3O4).

Great advantages of this process are:

  • high elimination performance,
  • compact process
  • Low power input.

Adsorption

The adsorptive capacity for phosphates were greatest where adsorbents were used without any treatment. Another concept was a phosphorus removal by orthophosphate nucleation and use of phosphate rock in a packed column system seemed to be an applicable technology as a ‘polishing’ process after a lime treatment. Over 80% efficiency was reached with the use of aluminium oxide (Wiess 1992). In the Netherlands wetlands have been applied for polishing the effluent from trickling filters. Its disadvantage is that P is stored in wetland organisms mostly in roots and in dead matter and only 7% of it appear to be removable by harvesting.

A Review and Update of the Microbiology of Enhanced Biological Phosphorus Removal in Wastewater Treatment Plants

Enhanced biological phosphorus removal (EBPR) from wastewater can be more-or-less practically achieved but the microbiological and biochemical components are not completely understood. EBPR involves cycling microbial biomass and influent wastewater through anaerobic and aerobic zones to achieve a selection of microorganisms with high capacity to accumulate polyphosphate intracellularly in the aerobic period. Biochemical or metabolic modelling of the process has been used to explain the types of carbon and phosphorus transformations in sludge biomass. There are essentially two broad-groupings of microorganisms involved in EBPR. They are polyphosphate accumulating organisms (PAOs) and their supposed carbon-competitors called glycogen accumulating organisms (GAOs). The morphological appearance of microorganisms in EBPR sludges has attracted attention. For example, GAOs as tetrad-arranged cocci and clusters of coccobacillus-shaped PAOs have been much commented upon and the use of simple cellular staining methods has contributed to EBPR knowledge. Acinetobacter and other bacteria were regularly isolated in pure culture from EBPR sludges and were initially thought to be PAOs. However, when contemporary molecular microbial ecology methods in concert with detailed process performance data and simple intracellular polymer staining methods were used, a betaproteobacteria called ‘Candidatus Accumulibacter phosphatis’ was confirmed as a PAO and organisms from a novel gammaproteobacteria lineage were GAOs. To preclude making the mistakes of previous researchers, it is recommended that the sludge ‘biography’ be well understood – i.e. details of phenotype (process performance and biochemistry) and microbial community structure should be linked.3

Nitrification, Denitrification and Biological Phosphorus Removal in Piggery Wastewater Using a Sequencing Batch Reactor

Nutrients in piggery wastewater with high organic matter, nitrogen (N) and phosphorus (P) content were biologically removed in a sequencing batch reactor (SBR) with anaerobic, aerobic and anoxic stages. The SBR was operated with 3 cycles/day, temperature 30 °C, sludge retention time (SRT) 1 day and hydraulic retention time (HRT) 11 days. With a wastewater containing 1500 mg/l ammonium and 144 mg/l phosphate, a removal efficiency of 99.7% for nitrogen and 97.3% for phosphate was obtained. Experiments set up to evaluate the effect of temperature on the process showed that it should be run at temperatures higher than 16 °C to obtain good removals (>95%). Batch tests (ammonia utilization rate, nitrogen utilization rate and oxygen utilization rate) proved to be good tools to evaluate heterotrophic and autotrophic biomass activity. The SBR proved to be a very flexible tool, and was particularly suitable for the treatment of piggery wastewater, characterized by high nutrient content and by frequent changes in composition and therefore affecting process conditions.4

Removal of Phosphorus and Organic Matter Removal by Alum during Wastewater Treatment

Ferron reagent and FTIR spectroscopy were used for the identification and characterization of the aluminum species formed during dephosphorization of simulated wastewater with and without organic matter. Evidence from FTIR spectroscopy showed the formation of aluminum hydroxyphosphate, hydroxy-Al–tannate and aluminum complexes containing both phosphorus and tannic acid. The surface reactivity of the solid products is proportional to the rate of reaction with ferron. The measured reactivities indicate that aluminum solid species with different surface properties were formed depending on solution components and method of precipitation. Tannic acid was found to inhibit phosphorus removal and the extent of inhibition increased with increasing concentration. When prehydrolyzed aluminum is exposed to tannic acid, the organic matter forms a coating on the surface of the inorganic solid during the aging process. Coprecipitation of aluminum, phosphate and tannic acid, which is synonymous with the addition of alum before or in the aerator, produces some soluble complex and some hydroxy-Al–phosphate–tannate complex, in the form of solid with very small particle size. This system gives high residual aluminum. The results suggest that it is advantageous to add at least a portion of the alum at the exit of the aerator. This enhances phosphorus removal by coprecipitation under conditions where the concentration of organic matter is relatively low and enhances removal of organic matter by postprecipitation onto the recycled sludge in the aerator.5

Microbial Selection of Polyphosphate-Accumulating Bacteria in Activated Sludge Wastewater Treatment Processes for Enhanced Biological Phosphate Removal

Activated sludge processes with alternating anaerobic and aerobic conditions (the anaerobic.aerobic process) have been successfully used for enhanced biological phosphate removal (EBPR) from wastewater. It is known that polyphosphate-accumulating bacteria (PAB) play an essential role for EBPR in the anaerobic.aerobic process. The present paper reviews limited information available on the metabolism and the microbial community structure of EBPR, highlighting the microbial ecological selection of PAB in EBPR processes. Exposure of microorganisms to alternate carbon- rich anaerobic environments and carbon-poor aerobic environments in the anaerobic.aerobic process induces the key metabolic characteristics of PAB, which include organic substrate uptake followed by its conversion to stored polyhydroxyalkanoate (PHA) and hydrolysis of intracellular polyphosphate accompanied by subsequent Pi release under anaerobic conditions. Intracellular glycogen is assumed to function as a regulator of the redox balance in the cell. Storage of glycogen is a key strategy for PAB to maintain the redox balance in the anaerobic uptake of various organic substrates, and hence to win in the microbial selection. Acinetobacter spp., Microlunatus phosphovorus, Lampropedia spp., and the Rhodocyclus group have been reported as candidates of PAB. PAB may not be composed of a few limited genospecies, but involve phylogenetically and taxonomically diverse groups of bacteria. To define microbial community structure of EBPR processes, it is needed to look more closely into the occurrence and behavior of each species of PAB in various EBPR processes mainly by molecular methods because many of PAB seem to be impossible to culture.6

References

1http://www.lenntech.com/phosphorous-removal.htm

2Zhang, Tianxi, Bowers, Keith E., Harrison, Joseph H., Chen, Shulin, 2009. Patent: Compositions And Methods For Wastewater Treatment.

3Linda L. Blackall, Gregory R. Crocetti, Aaron M. Saunders and Philip L. Bond, 2002. A review and update of the microbiology of enhanced biological phosphorus removal in wastewater treatment plants. Antonie van Leeuwenhoek, 81 ( 681- 691).

4D. Obaja, S. Macé, J. Costa, C. Sans and J. Mata-Alvarez, 2003. Nitrification, denitrification and biological phosphorus removal in piggery wastewater using a sequencing batch reactor. Biosource Technology, 87 (103- 111).

5OmoikeA. I and vanLoon, G. W, 1999. Removal of phosphorus and organic matter removal by alum during wastewater treatment. Water Research, 33 ( 3617- 3627).

6Mino T, 2000.  Microbial Selection of Polyphosphate-Accumulating Bacteria in Activated Sludge Wastewater Treatment Processes for Enhanced Biological Phosphate Removal. Biochemistry, 65 (341- 348). 



Get in Touch

Send us a message to know more on how we can help your organisation.