Daily pH Cycle and Ammonia Toxicity-Pond CO2 concentrations and pH, are affected by respiration and photosynthesis. Carbon dioxide is released during respiration and consumed for photosynthesis. As a result, pond pH varies throughout the day

Wonderful knowledge sharing by PC MOHAN SIR, GM. AND JKP SIR.TO MONITOR pH IN HOLDING POND.
The throughput of a conventionally designed pH neutralization / adjustment system is limited by several major short comings. These short comings pertain to pH probe response time, mixing efficiency, tank design, chemical metering precision, chemical reaction times, and pH control intelligence. "Optimized" pH control technology addresses each of these weak areas individually and synergistically. With the implementation of "Optimized" pH control. 

Controlling algae will prevent most causes of high effluent pH. A properly aerated lagoon should only experience minimal algae growth around its edges during the hottest summer months. The natural habitat for algae is at the surface of the water: If you disrupt that habitat, you also disrupt the algae growth in your wastewater lagoon. The more turbulence in the water, the better your chances are of treating lagoon algae and maintaining optimal pH levels.

Wastewater, pH Balanced For Treatment

Water Online's "Peer Perspectives" is a Q&A series that provides unique insight into the issues facing water and wastewater professionals by speaking directly to you, the reader. For this installment we spoke to Daniel Theobald, wastewater consultant and owner of Environmental Services. An accomplished writer andblogger for the industry, Dan was recently enlisted by the Water Environment Federation to revise its Manual of Practice (MOP-29) for biological nutrient removal (BNR).

In talking with Dan about important issues facing wastewater operators, his point of emphasis turned to pH control — a broader topic in that it affects all types of wastewater treatment, yet one that is too often overlooked. Since pH control became an overriding theme during our discussion (much the same as it does in practice), we narrowed our focus to shine a light on the subject. Read on for 7 key questions and answers regarding pH and wastewater.

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Why is controlling pH an important procedure in treating wastewater?

As a chemical component of the wastewater, pH has direct influence on wastewater treatability — regardless of whether treatment is physical/chemical or biological. Because it is such a critical component of the makeup of the wastewater, it is therefore critically important to treatment.

What steps are needed to control pH?

First of all, you have to identify the parameters — the pollutants or impurities — that are actually in the wastewater. Once the pollutants are identified, you should determine the starting and the ending pH values, along with a specific treatment procedure; then you have to select the appropriate chemicals best suited for treatment.

How do starting and ending pH values impact the treatment procedure?

It takes residence or contact time during wastewater treatment for the pH to adjust appropriately. A very narrow pH range (i.e., 7.0 to 8.0) requires less contact or residence time as compared to a wider pH range (i.e., 7.0 to 10.0), so the procedure is affected by the required pH adjustment range.

Why is chemical selection an important consideration in controlling pH?

Different chemicals have varying reaction times, which in turn have a major effect on pH adjustment and control. Therefore, the equipment residence or contact time is very relevant in relation to the chemical used for treatment.

Does the pH change immediately? If not, what are some considerations?

Actually, pH virtually never changes immediately. The rate of change depends on chemical reaction times, which are directly associated with tank volume, the amount of mixing, and all other aspects of the treatment procedure. Often, the pH can change after wastewater leaves the treatment tank. In those instances, the reaction time exceeds residence or contact time.

Can pH be controlled manually, or is automated instrumentation required?

Rigorous precision of pH control is often required for treatment, and it seldom occurs by attempting to control pH manually. There are multiple interferences when attempting to control pH manually, so automation is recommended.

Can equipment selection influence the overall outcome?

Absolutely. Equipment, instrumentation, and specific procedures are all very influential. For equipment, tank size and mixer selection, as well as location and use, are all influential. For instrumentation, including controllers, the type and settings are paramount. Individual procedures, especially specific chemical use, will also impact the overall outcome.

Ultimately, rigorous pH control improves wastewater treatment and simultaneously reduces chemical usage and the associated cost, therefore increasing profitability.

With best regards,

Connecting People to Nature’, the theme for World Environment Day 2017, 

Dr. AMAR NATH GIRI                       

EHSQ , NFCL 

M.Sc. -Environmental Science,Ph.D -Environmental Science law & DIPLOMA AS - P.G.D.E.P.L,CES, DCA,
EX IIM LUCKNOW FELLOW, EX RESEARCH SCIENTIST
IGIDR-MUMBAI
9912511918
amarnathgiri@nagarjunagroup.com
http://www.nagarjunafertilizers.com
http://www.gprofonline.com/members/Default.aspx

EHSQ BLOG : http://dramarnathgiri.blogspot.in/?view=magazine

---------- Forwarded message ----------
From: Amar Giri <goswami248@gmail.com>
Date: Sat, Sep 17, 2016 at 9:58 AM
Subject: Daily pH Cycle and Ammonia Toxicity
To: jkprasad@nagarjunagroup.com
Cc: K V S Murthy <kvsmurthy@nagarjunagroup.com>

Dear Sir,

Good morning,

SHARING , It is relevant to our holding pond .also  

it will be better to see pH every shift and finally avg value which will be below -8.

Ammonia is a nitrogen waste released by aquatic animals into the production pond environment.  It is a primary byproduct of protein metabolism.   Ammonia is excreted directly from the fish gill into the water.  Ammonia concentrations are usually at their highest late in the production season when biomass of the cultured species and the amount of protein fed are greatest.  Ammonia is toxic to aquatic life and toxicity is affected by pond pH.  Ammonia-nitrogen (NH₃-N) has a more toxic form at high pH and a less toxic form at low pH, un-ionized ammonia (NH₃) and ionized ammonia (NH₄⁺), respectively.  In addition, ammonia toxicity increases as temperature rises.

The measure of whether water is acidic, basic (alkaline) or neutral is known as pH.  A scale of 1 to 14 is traditionally used, which represents the negative logarithm of the hydrogen ion concentration.  A pH of 7.0 is neutral; above 7.0 is basic and below 7.0 is acidic; close to 7.0 is weak and far from 7.0 is strong.  It is a common perception that the pH of water is neutral and constant at a value of 7.0.   In an environment free of carbon dioxide, aquatic life, and compounds other than H₂O; pond pH would remain 7.0 or neutral.  However, this combination of conditions is unlikely to occur on our planet.  The pH of water is naturally acidic because the atmosphere contains carbon dioxide (CO₂). Carbon dioxide readily dissolves into water, raindrops and other sources of water exposed to air, forming a weak acid (H₂CO₃, carbonic acid).  Therefore, events in the aquatic environment that affect CO₂ concentrations also affect pH.  There are minerals in soil that can dissolve in water to create acidity and alkalinity as well.

With best regards,
 “Join the race to make the world a better place”.(2016)

Dr. AMAR NATH GIRI

EHSQ , NFCL
M.Sc. -Environmental Science,Ph.D -Environmental Science law & DIPLOMA AS - P.G.D.E.P.L,CES, DCA,
EX IIM LUCKNOW FELLOW, EX RESEARCH SCIENTIST
IGIDR-MUMBAI
9912511918
amarnathgiri@nagarjunagroup.com
http://www.nagarjunagroup.com
http://www.nagarjunafertilizers.com
http://www.gprofonline.com/members/Default.aspx

EHSQ BLOG : http://dramarnathgiri.blogspot.in/?view=magazine
http://dramarnathgiri.blogspot.in/2013/10/curriculum-vitae-of-dr-amar-nath-giri.html?q=BIO+DATA
http://dramarnathgiri.blogspot.in/2012/05/nagarjuna-management-services.html

Daily pH Cycle and Ammonia Toxicity

World Aquaculture, 34(2): 20-21.

                 

as PDF)

William A. Wurts, Ph.D.

Senior State Specialist for Aquaculture

Kentucky State University CEP at the UK Research and Education Center

P.O. Box 469

Princeton, KY  42445-0469

www.ca.uky.edu/wkrec/Wurtspage.htm

Ammonia is a nitrogen waste released by aquatic animals into the production pond environment.  It is a primary byproduct of protein metabolism.   Ammonia is excreted directly from the fish gill into the water.  Ammonia concentrations are usually at their highest late in the production season when biomass of the cultured species and the amount of protein fed are greatest.  Ammonia is toxic to aquatic life and toxicity is affected by pond pH.  Ammonia-nitrogen (NH₃-N) has a more toxic form at high pH and a less toxic form at low pH, un-ionized ammonia (NH₃) and ionized ammonia (NH₄⁺), respectively.  In addition, ammonia toxicity increases as temperature rises.

The measure of whether water is acidic, basic (alkaline) or neutral is known as pH.  A scale of 1 to 14 is traditionally used, which represents the negative logarithm of the hydrogen ion concentration.  A pH of 7.0 is neutral; above 7.0 is basic and below 7.0 is acidic; close to 7.0 is weak and far from 7.0 is strong.  It is a common perception that the pH of water is neutral and constant at a value of 7.0.   In an environment free of carbon dioxide, aquatic life, and compounds other than H₂O; pond pH would remain 7.0 or neutral.  However, this combination of conditions is unlikely to occur on our planet.  The pH of water is naturally acidic because the atmosphere contains carbon dioxide (CO₂). Carbon dioxide readily dissolves into water, raindrops and other sources of water exposed to air, forming a weak acid (H₂CO₃, carbonic acid).  Therefore, events in the aquatic environment that affect CO₂ concentrations also affect pH.  There are minerals in soil that can dissolve in water to create acidity and alkalinity as well.

Photosynthesis and Respiration

Pond CO₂ concentrations and pH, are affected by respiration and photosynthesis.  Carbon dioxide is released during respiration and consumed for photosynthesis.  As a result, pond pH varies throughout the day (Fig. 1).

The plant members of the pond plankton community, phytoplankton, absorb CO₂ for photosynthetic production of sugar.  As daylight progressively intensifies, the rate of photosynthesis increases and so does the uptake of CO₂.  The removal of CO₂ reduces the concentration of carbonic acid, and pond pH rises.  Late in the production season, high waste nutrient concentrations can promote dense phytoplankton   blooms   which,   in   turn,   can

remove all of the CO₂ from pond water during photosynthesis.  This can cause the water to become alkaline with pH levels greater than 9.0.  Pond pH is highest late in the afternoon -- a few hours before sunset.

After sunset, photosynthesis and CO₂ uptake stop. However, respiration continues day and night.  During respiration, plants and animals consume oxygen to free the energy stored in food.  The end product of respiration is CO₂, which is released directly into the water.  As photosynthesis is halted by the absence of light, CO₂ begins to accumulate and the carbonic acid concentration increases.  The rising concentration of carbonic acid causes the pH to fall. Toward the end of the production season, the biomass and respiration of cultured animals and phytoplankton is high. Nighttime concentrations of CO₂, and therefore carbonic acid, can become excessive, lowering pH below 7.0.  As such, pond pH would be lowest an hour or two before sunrise.

Effects of pH on Ammonia Toxicity

The daily interplay of photosynthesis and respiration creates a cyclical change in pond pH.  Pond water becomes most acidic just before the period of darkness ends and most alkaline after several hours of daylight.  The presence of un-ionized ammonia, the toxic form, increases as pH rises and decreases as pH falls which causes ammonia to become more ionized.  The concentration of un-ionized ammonia in production ponds is lowest just before dawn and highest late in the afternoon.

This has significant implications for water quality monitoring, especially several weeks prior to harvest when fish biomass is greatest.  For example (Table 1), a producer measures water quality at 0400 hr.  The total NH₃-N concentration is 2.7 mg/L, pH is 7.0, and water temperature is 28 ^oC.  The farmer then cross-references these values with a standard, pH-temperature table and calculates the concentration   of   “un-ionized”   NH₃-N  to  be 0.019 mg/L.  The  producer decides to check water quality again at 1600 hr and finds that total   NH₃-N  is  still  2.7  mg/L.  But,  pH   and water temperature have risen to 9.0 and 30 ^oC.  After checking the reference table, the farmer discovers that the un-ionized NH₃-N concentration is now 1.2 mg/L.  An un-ionized NH₃-N level of 0.019 mg/L would be considered    acceptable    for   channel   catfish production.  However, the un-ionized NH₃-N concentration of 1.2 mg/L recorded at 1600 hr could be lethal to channel catfish within several hours.  Over a 12-hr period, the un-ionized ammonia concentration increased approximately 63-fold.  The temperature change accounts for less than 10% of the increase in toxicity while the rise in pH from 7.0 to 9.0 is responsible for more than 90%.

Table 1.  Amount of total ammonia-nitrogen (Tot/NH₃-N) present as un-ionized ammonia-nitrogen (UI/NH₃-N), for early morning and late afternoon pH and temperature measurements in a hypothetical production pond.

Time	Tot/NH3-N (mg/L)	Temp °C	pH	UI/NH3-N (mg/L)
0400 hr 1600 hr	2.7 2.7	28 30	7.0 9.0	0.019 1.2

Measuring pH and Ammonia

Photosynthesis and respiration have significant effects on pond pH.  Because those processes affect pH, ammonia toxicity is influenced also.  When monitoring water quality, it is important for producers to understand the daily shifts in pH and their impacts on un-ionized ammonia concentrations.  First, for ammonia-nitrogen measurements to be useful, pH and NH₃-N must be measured at the same time.  Second, a morning pH determination is not meaningful for assessing whether daily ammonia concentrations have reached unsafe levels in ponds.  To have any practical value for pond management decisions, NH₃-N and pH should be tested late in the afternoon.  A solid grasp of the pH cycle and its interrelationship with NH₃ is critical for the successful culture of any aquatic specie