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Nitrogen and phosphorus recovery from anaerobic co-digestion…struvite precipitation

Sat, 22Jun2013 Comments off

In the ongoing efforts to  extend appropriate sanitation to the millions in the world lacking it, it benefits all to show that the byproduct of sanitation is not waste, but a valuable agricultural resource. Some even call it the new gold.   This  tangential research below is important in helping  get that gold and getting to that goal.

New research by

Nitrogen and phosphorus recovery from anaerobic co-digestion residues of poultry manure and maize silage via struvite precipitation

Abstract

Anaerobic digestion is commonly used for the stabilization of agricultural and animal wastes. However, owing to the stringent environmental criteria, anaerobic digester effluents need to be further treated to reduce nutrient loads to the receiving water bodies. Struvite precipitation is one of the promising techniques applied for this purpose. Yet, in the majority of cases, struvite precipitation is only applied to the liquid phase of anaerobic digester effluents. This study investigated the recovery of nutrients from both the liquid and the solid phases of the phase-separated effluent of a full-scale biogas plant co-digesting poultry manure and maize silage. Struvite precipitation in the liquid phase led to 72.1% and 95.1% average removal efficiencies of ammonium-nitrogen (NH4-N) and orthophosphate respectively. Changing the external phosphorus source did not make any statistically significant difference in nutrient removal. An acidic phosphorus-dissolution process was applied to the solid phase sample to obtain a phosphorus-enriched solution. More than 90.0% of both NH4-N and PO4-P were recovered from the phosphorus-enriched solution with the amendments of magnesium and phosphorus. In the experiments performed without any addition of external magnesium- and phosphorus-containing chemicals, almost complete (99.6%) PO4-P recovery and partial (14.6%) NH4-N recovery were obtained. The results of this study could contribute to the understanding of nutrient recovery from anaerobic digestion residues of manure and agricultural wastes by struvite precipitation.

More info /source:

Side note while WASHLink appreciates the above efforts, we appeal for more researchers to seek out open access scientific and scholarly journals to publish their work. more on OA by an example

 

Stanford Nitrogen Group – Energy from Waste Nitrogen – Wastewater Treatment research

Mon, 28Jan2013 Comments off

 When looking at sanitation/wastewater treatment and making it economically feasible for more parts of the world, this is very interesting research.   Some will say it has roots in the fact that there is “gold”  in out crap…

Related links to this research:

Wastewater as a Clean Energy Source:

  …On May 1, a panel of judges awarded the $100,000 National University Clean Energy Business Challenge prize to the Stanford team for its project to convert nitrogen waste into nitrous oxide that is then used for clean power generation….

Paper: Nitrogen removal with energy recovery through N2O decomposition:

by Yaniv D. Scherson ,  George F. Wells ,  Sung-Geun Woo ,  Jangho Lee ,  Joonhong Park ,  Brian J. Cantwell and Craig S. Criddle

A new process for the removal of nitrogen from wastewater is introduced. The process involves three steps: (1) partial nitrification of NH4+ to NO2; (2) partial anoxic reduction of NO2 to N2O; and (3) N2O conversion to N2 with energy recovery by either catalytic decomposition to N2 and O2 or use of N2O to oxidize biogas CH4. Steps 1 and 3 have been previously established at full-scale. Accordingly, bench-scale experiments focused on step 2. Two strategies were evaluated and found to be effective: in the first, Fe(II) was used to abiotically reduce NO2 to N2O; in the second, COD stored as polyhydroxybutyrate (PHB) was used as the electron donor for partial heterotrophic reduction of NO2 to N2O. ….

Researchers use rocket science for sustainable waste treatment process

Normally, we want to discourage these gases from forming,” said Craig Criddle, a professor of civil and environmental engineering and senior fellow at the Woods Institute for the Environment at Stanford. “But by encouraging the formation of nitrous oxide, we can remove harmful nitrogen from the water and simultaneously increase methane production for use as fuel.

Urine Diverting Toilets in Climates with Cold Winters

Thu, 04Nov2010 2 comments

There was post on the yahoo group ECOSANRES asking about Cold Climate toilets -Cold weather toilets.

A reply mentioned this PDF:

Urine Diverting Toilets in Climates with Cold Winters Technical considerations and the reuse of nutrients with a focus on legal and hygienic aspects.

While  the report is several year old,  the $h1t is still good and worthy of summarizing

basic facts:

Authors and Editors:

Chapters/ sections

1 – Summary
2 – Dry Urine Diversion
3 – EU directives relating to dry urine diversion where urine and faeces
4 – Legal aspects
5 – Cold temperature aspects
-   Freezing of urine
-   Hygiene and treatment of urine
-   Pharmaceuticals and hormones
-   Hygiene and treatment of faeces
-   Technical aspects: construction and maintenance of
-    urine diverting toilets in climates with cold winters
-   Pipes for urine
-   Storage
-   Odour control with ventilation
-   System for reuse of urine and faeces in crop production
-   Home gardens
-   Large Scale Agricultural Production
6 – Examples from pilot projects and research from the northern hemisphere
7 – Knowledge gaps and identified research needs
8 – Annex

Three key points  from the Reportssummary are:

“There are functioning examples of dry urine diversion in regions in the world with cold winter climates. The examples presented in the report show that it is possible to arrange agricultural reuse of urine and faeces in large or small scale crop production.”

“The fact that there are only short periods during the year when urine can be used as a fertiliser place demands on a storage system for the urine. There are a few alternatives; one of the most economic may be to arrange storage on a farm, in covered storage containers previously used for animal urine.”

“There are still development needs and knowledge gaps. Some of these are related to temperate and cold climates, such as the fate of microorganisms in urine at temperatures below freezing. However, this should not be considered a major constraint to the development of dry urine diversion, since the risk is relatively low, and can be handled through combination with other hygienic activities.”

The report reprints 3  basic but useful  tables from other organizations:

1: Recommended guideline storage times for urinea based on estimated pathogen contentb and recommended crop for larger systemsc (WHO, 2006).

2: Requirements on storage and allowed crops for diverted human urine that is collected from larger systems. (Swedish EPA, 2002).

3: Recommendations for storage treatment of dry excreta and faecal sludge before use at household and large-scale (municipal) levels. The treatments assume no
addition of non-sanitised material (WHO, 2006).

Again the report is a quick and easy read, providing a good  preface to a much larger  document that needs to be written on the subject.    The report  ends  nicely,  saying  we need more  research :

There are some definite areas where there is a need of systematic research and development (R&D). Some of these, especially related to winter climate aspects, are specified in the following text.

Research needs

One of the most discussed questions regarding urine diversion is the fate of pharmaceutical residues after excretion, and how this affects choice of collection and treatment of human excreta. Research on fate of pharmaceuticals in waste water treatment plants is being undertaken in Germany and Sweden. No known field studies are taking place on fate of pharmaceutical residues when urine or sewage sludge is applied to the soil. The current recommendation to use urine as a fertiliser in agriculture rests on the analysis that the soil system is well suited to digest harmful organic substances due to microbial life in the surface layers of soil. This would be an interesting field of study that can give valuable information on design of reuse systems.

Sanitisation of faeces is another aspect that needs attention. The WHO guidelines on the reuse of human excreta in agriculture mention the alkaline treatment by adding ashes or alkaline substances with a storage time of 6 month ( > 35 °C ) as a possible way to sanitise faeces, or 1,5 – 2 years storage time. The temperature intervals given do not cater for needs in temperate or cold climates, which means that knowledge on treatment of faeces in this region should be developed. Research on more simple and robust treatment methods is needed.

Suggested applied R&D projects

-   Establishment of new pilot projects and evaluation of existing projects. Monitoring and evaluation of existing dry urine diversion projects is a costefficient way of generating knowledge. Dissemination of results, regardless of if they are positive or negative, from existing pilots is vital. The establishment of new pilot projects will also contribute to the bank of knowledge.

-   Sanitisation of faecal fraction: research on requested storage in ambient or alkaline environment in temperate and cold climates (winters with temperatures far below zero).

-   Sanitisation of faecal fraction: research on the implementation of chemical sanitisation of faeces with urea. This is an interesting method, but the practical implications need to be studied and developed.

-   Sanitisation of urine: what happens in the urine when it is frozen and what are the implications for storage intervals?

-   Pharmaceutical residues: studies of soil system when urine is used as a fertiliser. Effect on microbial community, speed of decomposition. Comparisons with sewage sludge, farmyard manure.

-   Toilet design: development of risers and squat-plates for local production. Care given to needs of different users: children, disabled, elderly, men, women. Toilets of today need development since many do not divert as much urine as possible, and are unnecessarily difficult to clean.

-   Systems analysis from an economic point of view. Comparison of investment and maintenance costs of urine diversion systems and conventional sanitation.

-   Systems analysis from an environmental point of view. How do different activities affect the sustainability of the system, for example fertilisation strategies, choice of tank, joint measures or single toilets?

-   What are the economical incentives for implementation of urine diversion? How to design the economical system with the regard to municipal responsibility and financial support/ interactions. How should the systems be organized and which are the most important drivers for the different stake holders.”

other  related links

Denitrification – is back, but anammox stays?

Tue, 08Sep2009 Comments off

Denitrification, its importance once diluted, may be back on top, Princeton-led team says

source Princeton University:

http://www.princeton.edu/main/news/archive/S25/19/05M98/index.xml?section=topstories

Posted September 2, 2009; 01:00 p.m. by Kitta MacPherson

After more than a decade of inquiry, a Princeton-led team of scientists has turned the tables on a long-standing controversy to re-establish an old truth about nitrogen mixing in the oceans.

For decades, scientists thought they had a handle on the workings of an intricate natural mechanism known as the nitrogen cycle, essential to maintaining life on Earth. This process, one of nature’s most elegant sleights-of-hand, shuttles nitrogen from the soils to the oceans to the atmosphere and back.

A key part of that cycle, researchers once thought, was a process known as denitrification. In low-oxygen — or anaerobic — conditions seen in large stretches of ocean sediments and in a few important regions of the open ocean, bacteria act as “denitrifyers,” performing the crucial task of gobbling up nitrates and converting them to nitrogen gases, which complete the cycle by flowing back to the atmosphere.

In 1995, a group of Dutch scientists who had been studying the cycling of nitrogen through wastewater treatment plants came up with a startling conclusion. A new process, which they called anaerobic oxidation or “anammox” and that involved different bacteria, was the real player in removing nitrogen in low-oxygen environments, they said. They found the process worked to break down materials in sewage, and they confirmed that the mechanism also was operating in low-oxygen marine environments. They went so far as to suggest that the nitrogen cycle for oceans needed to be revised, as denitrification, according to their inquiry, did not play the major role that had been thought.

The notion was controversial and did not sit well with some scientists.

Now, a research team, led by Bess Ward, the William J. Sinclair Professor of Geosciences at Princeton University, writing in the Sept. 3 issue of Nature, is presenting data that could re-establish denitrification as the main actor in returning nitrogen to the air. After traveling through some of the key low-oxygen sites of the world’s oceans, the team has found the telltale chemical signatures proving that denitrification and not anammox is the pivotal process at work most of the time.

Amal Jayakumar and Bess Ward

From left, Amal Jayakumar and Bess Ward of Princeton University, and Dave Langner, a marine technician, collect water samples from the Arabian Sea for their study of the nitrogen cycle. They deployed the instrument package from aboard the Scripps Institution of Oceanography’s ship, the R/V Roger Revelle. (Photo: Courtesy of the Ward Laboratory)

“In our paper, we report that in the world’s largest anoxic marine ecosystem — the low-oxygen waters of the Arabian Sea — denitrification rather than anammox is the dominant process,” said Ward, who is also chair of the Department of Geosciences at Princeton. “If denitrification is important in the Arabian Sea, then it is important on a global scale, and the nitrogen cycle must be evaluated in that light.”

The work, according to a leading expert in the marine nitrogen cycle, confirms his own observations of seawater processes showing that denitrification is key and indicates that the current mainstream view in science may be based on a false impression. “My suspicions that future work would, once again, demonstrate the importance of conventional denitrification have now been confirmed,” said Louis A. Codispoti, an oceanographer and research professor at Horn Point Laboratory, part of the University of Maryland in Cambridge, who was not involved with the research.

The researchers who discovered the anammox process nearly 15 years ago, led by Gifjs Kuenen, then at the Delft University of Technology in the Netherlands, moved beyond the original discovery in wastewater treatment plants and found the reaction was also at work in removing nitrogen in a few regions of the ocean known as “oxygen minimum zones.” Zeroing in on a low-oxygen zone off the coast of Peru, the work of Dutch, Danish and German scientists found that anammox reactions, rather than denitrification, were operating there.

“That was astounding,” Ward remembered.

Thinking there may be a problem with the methodology or that scientists didn’t understand the nitrogen cycle as much as they thought they did, she began to devise experiments to seek answers.

Working with other members of her team over the next decade, they learned the methods of the European experts and started to plan to replicate the studies. In 2005, they confirmed that bacteria supporting the anammox reaction dominated the removal of nitrogen in a low-oxygen region off the Peru coast. But when they took samples of water in the Arabian Sea, they found just the opposite — denitrification was a major force there. The European researchers had found anammox in the Peru system but had never reported on the Arabian Sea.

The notion that microbial processes can vary in low-oxygen zones around the world is startling and important to know, the researchers said.

“We care because nitrogen is a key limiting nutrient to primary productivity,” said Jeremy Rich, a former postdoctoral fellow in Ward’s lab and now an assistant professor of environmental studies at Brown University, who contributed to the study. “We already knew these zones removed nitrogen, but now that we know the actual processes taking place, we’ll be in a much better position to predict how these zones change. And how these zones change will in turn influence primary productivity.”

The findings have forced the scientists to re-evaluate what they already knew.

“This made us think — this means the Arabian Sea is somehow different from the Peru system,” Ward said. “Previously, we thought they were the same. Clearly, something was different and that, in and of itself, is an important insight. And, clearly, denitrification is important — you cannot rewrite the nitrogen cycle.”

Because the Arabian Sea is the world’s largest anoxic marine ecosystem, that body’s most dominant process is almost certainly the primary way for nitrogen to be removed from the world’s oceans.

To confirm the conclusions, the team designed a new way of sampling and identifying chemicals and repeated the experiments. The results were the same.

The nitrogen cycle is one of the most important nutrient cycles in nature, providing a transformative process in which nitrogen is taken from the atmosphere and converted into a form that can be consumed by plants. Nitrogen makes up about 80 percent of the earth’s atmosphere. It is used by living organisms to produce a number of complex organic molecules, including DNA.

Processing or fixation is necessary to convert gaseous nitrogen into forms usable by living organisms. Most is done by bacteria that possess a nitrogenase enzyme that combines gaseous nitrogen with hydrogen to produce ammonia, which is then converted by the bacteria to make their own organic compounds.

In low-oxygen conditions, denitrification by bacteria occurs when nitrates are converted to nitrogen gases like nitrous oxide and returned to the atmosphere. In the anammox process, nitrates are reduced to nitrites and then combine with ammonium before returning to the atmosphere.

In addition to Ward and Rich, other authors on the paper include: Silvia Bulow, a graduate student, and Amal Jayakumar, a senior professional specialist, in Princeton’s Department of Geosciences; Allan Devol, research professor of oceanography, and Bonnie Chang, a graduate student, at the University of Washington; and Hema Naik, a scientist, and Anil Pratihary, a graduate student, at the National Institute of Oceanography in India.

The research was funded by the National Science Foundation.

source: Princeton University

http://www.princeton.edu/main/news/archive/S25/19/05M98/index.xml?section=topstories

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