The Copper Sorption Capabilities Of Oreochromis Niloticusfish Scales With The Application Of Varied Ph Levels Under Two States

Water pollution has been defined as the introduction of uncharacterized substances into bodies of water to the point where the substances interfere with beneficial use of the water or with the natural flow of ecosystems.

The issue itself is also eminent all over the world and is developing rapidly. It is due to the higher disposal rates of foreign substances as the world progresses more into the advancement of technology. Gradually, the effects of the stockpiled waste grow adverse, heavily impacting the organisms that use those waters.

In the national scale, Philippines’ condition of water pollution has intensified. According to Greentumble (2015), over 47% of all surveyed water bodies in the country have good water quality, 40% have only fair water quality, and 13% have poor water quality. Around 50 of the 421 rivers in the Philippines are now considered to be “biologically dead,” supplying sufficient oxygen for only the hardiest species to survive there. An example of this is the Pasig River.

There are several factors that contribute to water pollution. The most common causes are agricultural and industrial wastewaters. Agricultural wastewater pertains to organic waste such as livestock manure, decayed plants, and excess fertilizers. This is more prominent in rural areas which are more invested in the aspect of agriculture. On the other hand, industrial wastewater is prominent in areas like Metro Manila. Some of the pollutants are heavy metals like copper. The effects of this, in comparison to agricultural wastewater, are much more adverse. It ranges from vomiting, diarrhea, stomach cramps, and nausea, to liver damage and kidney disease. The presence of heavy metals poses a large threat to both the environment and its inhabitants. That is why people resort to conventional methods like physical, chemical, and physiochemical processes to eliminate the concentration of heavy metals from wastewater. But despite the deleteriousness of the threat, the use of this is limited due to its high operating costs, low selectivity, incomplete removal, and production of excess wastes. A new method, called biosorption, was introduced as an alternative to conventional methods for the removal of heavy metals from waste water. Biosorption can be defined as the ability of biological materials to accumulate heavy metals from wastewater through metabolically mediated or physio-chemical pathways of uptake.

It was presumed that by using this new method in which biomass is used as a sorbent, the toxic pollutants could be selectively removed from aqueous solutions to desired low levels. Seashell, mandarin peels, rice bran, crab carapace, pecan nutshell, algae-yeast, peanut shell, palm shell, and several other materials have been discovered as a natural biosorbents to remove heavy metals. Recently, studies had reported the used of fish scale in biosorption. Fish scales are considered as biological wastes, usually found on market areas before ending up in dumpsites. With the introduction of fish scales as biosorbents, the material has been given more uses in the field of science. But there are external factors that can affect the reach of its efficiency. One of the factors being the pH level of the water previously inhibited by those fish scales.

Recent studies showcase the capabilities of fish scale biosorbents in wastewater metal ion removal such as the utilization of Mozambique Tilapia fish scales as biosorbents for the removal of lead and zinc ions. A common pattern seen throughout most of those research studies was the use of stock solutions. That was mainly due to biosorption usually being initiated after filtering excess contaminants on the wastewater. Therefore, traditional filtering processes must be done before starting the biosorption process. The researchers of the studies utilized stock solutions in order to maintain a constant setup, which was also offers manipulability.

One of the earlier studies, fish scales of Tilapia nilotica Linnaeus were made use to observe copper sorption capabilities under different biosorbents to copper mass ratios and contact times. It was stated that there is a possibility that the physical properties of fish scales might have effect on the absorption rate due to the surface area. Considering all of this, the study is aimed to investigate the interaction of fish scales to varying pH levels under two setups, non-pulverized fish scales and pulverized fish scales. The usage Nile tilapia (Oreochromus tilapia) scales will be observed due to its availability. For the varying pH levels, three setups composed of solutions containing pH 5 and 6 respectively would be utilized. And due to availability, the use of copper (II) sulfate to create copper stock solution setups will be regarded.

Tilapia (Oeochromisniloticus)

The Nile tilapia Oreochromis niloticusis a deep-bodied fish with cycloid scales. Silver in color with olive/grey/black body bars, the Nile tilapia often flushes red during the breeding season. It grows to a maximum length of 62 cm, weighing 3.65 kg (at an estimated 9 years of age). The average size (total length) of O. niloticus is 20 cm. O. niloticus is native to central and North Africa and the Middle East. It is a tropical freshwater and estuarine species. It prefers shallow, still waters on the edge of lakes and wide rivers with sufficient vegetation. Male fish initiate breeding with the creation of a spawning nest, which is fiercely guarded. When the water temperature increases above 24°C, a female will lay her eggs into the nest. These are then fertilized by the males before the female collects them in her mouth (known as mouth brooding). The eggs and the fry which then hatch are incubated and brooded in this manner until the yolk sac is fully absorbed two weeks later. The number of eggs a female will produce is dependent on body size. This can range from 100 eggs (produced by a 100g fish) to 1500 eggs (spawned by a 1 kg fish). The females will not spawn while brooding. Males on the other hand fertilize the eggs of multiple females continuously given optimal environmental conditions.

Nile tilapia have been farmed for centuries. The culture of the tilapia genus on a global scale, primarily Oreochromis mossambicus, began in the 1940s. However, it was not until the 1960s that O. niloticus was exported worldwide. Aquaculture was herald0ed as the perfect protein production technique for developing countries during the 1960s and 1970s. Aid organizations promoted aquaculture as a means of improving food security with low grain to feed conversion rates, and minimal environmental impacts. This global popularity has led to a number of important developments in culture techniques. Initially, tilapia was allowed to breed freely. However, farmers and scientists observed that this led to the production of smaller fish. In the 1960s, attempts were made to produce male monosex populations through hybridization between different tilapia species. This proved problematic and gradually females reappeared in the progeny. Major technological developments in the 1970s allowed for the successful production of all-male populations through the use of sex reversing hormones which resulted in higher returns from tilapia farming. Following this, and further research into culture processes, the industry boomed.

Today, tilapia is often farmed with multiple species in the same pond, such as shrimp and milkfish. This not only optimizes the financial return if space is limited, but also helps prevent the growth of harmful bacteria and serves to remove excess organic matter in the water. Genetic modification of the species has also been undertaken to maximize farming efficiency. For example, the Genetic Improvement in Farmed Tilapia (GIFT) project in the Philippines created strains of O. niloticus that grew up to 60% faster than their relatives. However, in Africa, the use of improved stock lines is rare due to concerns regarding genetic modification. As a result, many tilapia farms use brood stock which underperforms by 20-40% relative to wild individuals. There is great scope for improvement in this regard, either by rotational mating or the introduction of improved strains.

Fish Scales

Fish scales are hard skeletal elements composed of a mineral phase of calcium-deficient hydroxyapatite and an extracellular matrix, mainly closely packed type I collagen fibers, forming a plywood-like structure.

Scales provide a flexible and protective outer layer on the dermis of a large variety of fish. The arrangement of fish scales provides a flexible skin that allows for changes in shape. Currey has reported that some fish scales are so tough that they cannot be easily fractured even after immersion in liquid nitrogen. In addition, it has been shown that the ridges and grooves on the surface of some fish scales may reduce the swimming drag forces.


Biosorption may be simply defined as the removal of substances from solution by biological material. Such substances can be organic and inorganic, and in soluble or insoluble forms. Biosorption is a physico-chemical process and includes such mechanisms as absorption, adsorption, ion exchange, surface complexation and precipitation. It is a property of living and dead biomass (as well as excreted and derived products): metabolic processes in living organisms may affect physico-chemical biosorption mechanisms, as well as pollutant bioavailability, chemical speciation and accumulation or transformation by metabolism-dependent properties. Some researchers include all biotic and abiotic mechanisms in effecting pollutant removal from solution under a ‘biosorption’ definition, especially when living cell systems are used, but this is not strictly accurate. The target substances for traditional adsorption/absorption processes are most organic contaminants and selected inorganic contaminants, such as toxic metals, from liquid and gas streams. Most biosorption research has concentrated on metals and related elements and several authors have emphasized this and defined biosorption as the removal of metal or metalloid species, compounds and particulates by biological material. Several other definitions also exclusively refer to microbial material in view of the predominant focus of most biosorption-related research on microbe-related systems.

The term biosorption can describe any system where a sorbate (e.g. an atom, molecule, a molecular ion) interacts with a biosorbent (i.e. a solid surface of a biological matrix) resulting in an accumulation at the sorbate – biosorbent interface, and therefore a reduction in the solution sorbate concentration. Apart from the removal of organic substances, metal and radionuclide pollutants from contaminated matrices (which can include waste process streams, washes and volatiles, soil and other leachates, extracts, etc.) for environmental protection, biosorption also has application for subsequent recovery and use of precious metals, e.g. gold.

Heavy Metals

Heavy metals are naturally occurring elements and are present in varying concentrations in all ecosystems. There is a huge number of heavy metals. They are found in elemental form and in a variety of other chemical compounds. Those that are volatile and those that become attached to fine particles can be widely transported on very large scales. Each form or compound has different properties which also affect what happens to it in food web, and how toxic it is. Human activities have drastically changed the biochemical cycles and balance of some heavy metals. Between 1850 and 1990, production of copper, lead and zinc increased 10-fold. The main anthropogenic sources of heavy metals are various industrial processes, mining, foundries, smelters, combustion of fossil fuel and gasoline, and waste incinerators. The major heavy metals of concern to EMEP are Hg, Cd and Pb, because they are the most toxic and have known serious effects on e.g. human health. Environmental exposure to high concentrations of heavy metals has been linked with e.g. various cancers and kidney damage. There are considerably more measurements data on Hg, Cd and Pb in Europe than for other metals And 21 ratifications and entered into force by the end of 2003. Complete and accurate data on heavy metal emissions are thus increasingly important within the CLRTAP convention. In particular, reliable emission data are needed to assess further measures to reduce environmental exposure to heavy metals (HMs) as well as to understand and predict source-receptor relationships of heavy metals on a regional scale. Three particularly harmful metals are targeted in the protocol, namely cadmium (Cd), lead (Pb) and mercury (Hg). In accordance with this agreement, parties will have to reduce their emissions for these three heavy metals below their levels in 1990 (or an alternative year between 1985 and 1995). The Protocol further aims to cut emissions from various industrial sources, selected combustion processes as well as waste incineration. It furthermore lays down stringent limit values for emissions from stationary sources and suggests best available techniques (BAT) for these sources, such as special filters or scrubbers for combustion sources or mercury-free processes.


In chemistry, pH is a measure of the activity of the (solvated) hydrogen ion. In other words, it is a measure of hydrogen ion concentration. Pure water has a pH very close to 7 at 25°C. Solutions with a pH less than 7 are said to be acidic, and solutions with a pH greater than 7 are said to be basic or alkaline. The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. The pH of different cellular compartments, body fluids, and organs is usually tightly regulated in a process called acid-base homeostasis. Microorganisms live and thrive within specific pH levels.

The optimum growth pH is the most favorable pH for the growth of an organism. The lowest pH value that an organism can tolerate is called the minimum growth pH and the highest pH is the maximum growth pH. These values can cover a wide range, which is important for the preservation of food and to microorganisms’ survival in the stomach. Most bacteria are neutrophiles, meaning they grow optimally at a pH within one or two pH units of the neutral pH of 7. Most familiar bacteria, like Escherichia coli, staphylococci, and Salmonella spp. are neutrophiles and do not fare well in the acidic pH of the stomach. However, there are pathogenic strains of E. coli, S. typhi, and other species of intestinal pathogens that are much more resistant to stomach acid. In comparison, fungi thrive at slightly acidic pH values of 5.0–6.0.Microorganisms that grow optimally at pH less than 5.55 are called acidophiles. For example, the sulfur-oxidizing Sulfolobus spp. isolated from sulfur mud fields and hot springs in Yellowstone National Park are extreme acidophiles. These archaea survive at pH values of 2.5–3.5. The vagina’s acidity plays an important role in inhibiting other microbes that are less tolerant of acidity. Acidophilic microorganisms display a number of adaptations to survive in strong acidic environments. For example, proteins show increased negative surface charge that stabilizes them at low pH. Pumps actively eject H+ ions out of the cells. The changes in the composition of membrane phospholipids probably reflect the need to maintain membrane fluidity at low pH.

At the other end of the spectrum are alkaliphiles, microorganisms that grow best at pH between 8.0 and 10.5. Vibriocholerae, the pathogenic agent of cholera, grows best at the slightly basic pH of 8.0; it can survive pH values of 11.0 but is inactivated by the acid of the stomach. Extreme alkaliphiles have adapted to their harsh environment through evolutionary modification of lipid and protein structure and compensatory mechanisms to maintain the proton motive force in an alkaline environment. For example, the alkaliphile Bacillusfirmus derives the energy for transport reactions and motility from a Na+ ion gradient rather than a proton motive force. Many enzymes from alkaliphiles have a higher isoelectric point, due to an increase in the number of basic amino acids, than homologous enzymes from neutrophiles.

13 January 2020
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