Water is not everything, but everything is nothing without water. Water constitutes about 70% of the surface of the earth and 97% of this water is present at sea level,2% is locked up at sea level and so only 1% is available for usage.Therefore, it is essential to conserve water. The preparation of drinking water, cleaning difficult waste-water and improvement of water quality in closed circuit needs a close monitoring and a hygienic process that will not be detrimental to human health.
Clarification of water as an aid to sedimentation of particulate matter has been practiced from ancient times. The Egyptian and Rome practiced a form of coagulation as early at 200BC. (Zheng, 2013).Moreso, increasing industrialization which has been accepted as an enviable choice due to its contribution to economic growth, has considerably raised the rate of water pollution, especially, from industrial sources and this has become a major environmental concern (Sarkar, 2006).
The disposal of untreated or partially treated waste water could result in long term undesirable negative impacts, especially on the environment, aquatic life forms and human health (Lin, 2011). When pollutants from waste water are discharged into natural water bodies, the water bodies becomes toxic and contaminated and may consequently pose a major threat to human beings. Water contains about 78% of the earth’s surface which is a source of life and energy. However millions of people doesn’t have access to safe water for drinking purposes and human utilization as a result of human negligence. Thus necessitating the need for adequate treatment of waste water before discharging into the environment.
Although in previous decades chemical treatment of waste water was inadequate, significant research outcome have shown that chemical coagulation is a viable treatment process for the treatment of waste water (Taniket al., 2002). Nowadays, the process of clarification (coagulation – flocculation and sedimentation) is employed worldwide in the water/waste water treatment industry (Olaniranet al., 2009) as the process of coagulation – flocculation in waste water treatment is a convenient and efficient technique for removing suspended solids (S S), colloids, and cell debris (Ganguli et al ., 2008).
The process involves the use of chemical coagulants such as ferric salts (Taniket al., 2002) Aluminium Sulfate, Aluminium Chloride and Poly acrylamide (Gurumoorthyet al., 2011).
However, these coagulants have been implicated in undesirable health condition (Lian etal., 2008). For example, polyacrylamide contains acrylamide monomers verified to be both neurotoxic and carcinogenic to humans (Zhang et al., 2012).
On the other hand, a link between aluminium in drinking water and human neurological disorders, such as dialysis encephalopathy, was established with excess aluminium in daily state fluid shown to be harmful to dialysis patients (Zheng, 2008). Thus heath implication of chemical coagulant/flocculant has necessitated the need for safe alternatives.
Though almost all natural surface waters contain colloidal substances that are not removed rapidly by sedimentation, consequently, it is necessary to catalyze this sedimentation by physical or chemical process which is called flocculation. Flocculation refers to the process by which destabilized particles actually conglomerate into larger aggregate so that they can be separated from the waste water (Drosteet al., 1997).Flocculation is an important operation in solid-liquid separation. Flocculation is a process of bringing together small particles to form larger particles.
Flocculation process is a process that cut across special processes such as coagulation which is a process whereby chemical are added to water resulting in a reduction of forces tending to keep suspended particles. By adding a simple flocculant which reduce the electrostatics repulsion, the aggregation takes place. Also floc formation where the flocculant molecules attach themselves to the surface of suspended particles at one or more adsorption sites, and that part of the chain extend out into bulk of the solution. The free form of the flocculant is then able to adsorb onto another suspended particles. When contact is made, the bridge are achieved and the flocs are formed.
The flocculants or flocculating agents; either have synthetic or natural origin are utilized as the sedimentation aids and thus, bringing about the solid-liquid separations by the process of flocculation (Lachhwani, 2005).Flocculants act on the molecular level on the surface of the particles thereby reducing the repulsive forces and mounting attractive forces (Sharma et al., 2006). Their addition enables dispersed particles to aggregate together to form flocs of a size and allows them to settle speedily for clearing the system (Sharma et al., 2006). These flocculants can be classified as inorganic, organic and natural organic flocculants.
Chemical flocculants include the inorganic flocculant (ferric chloride, Aluminum sulphate and calcium chloride) and organic flocculant (polyacrylamide derivates)
These are commonly used since the ancient time.Inorganic polymers include polyaluminium derivatives that was used in waste water treatment (Kuraneet al.,1986) and ferric chloride and poly aluminium silicate sulfate are commercially used in drinking water production ( Sharma et al., 2006). The inorganic flocculant refers to the salts of multivalent metals, like aluminium, calcium and iron. Inorganic flocculant suffer from many distinct disadvantages, the most serious of which is the toonage of flocculant involved. One requires a large volume of inorganic salts to obtain the same results that can be obtained with a very small amount of polymeric flocculant.
Moreover, the inorganic salts are only effective over a particular pH, there is frequent need for pH adjustment. Its advantages are:
- Inorganic flocculants are cost effective.
- Inorganic flocculants have high flocculating activities.
However, they have the following disadvantages:
- They are non-biodegradable.
- Inorganic flocculant are harmful to human health e.g. polyacrylamide contains acrylamide monomers verified to be both neurotoxic and carcinogenic to human.
- Large usage of inorganic material produce a lot of sludge.
- Large amount of inorganic flocculant is needed to obtain a very good result.
- Very sensitive to pH.
- Competent only to few disperse systems while not working for others.
- Cannot coagulate very fine particles.
According to (Kuraneet al., 1986), these are frequently used as economical and powerful flocculating agents for dredging fields, plant wastewater treatment, etc. These organic synthetic high-polymer flocculants have been most commonly utilized due to their flocculating effectiveness and low cost (Salehizadeh and Shojaosadati, 2001). Organic flocculants enhance the flocculation of suspended solids in the treatment of process water, wastewater, and effluents. They are available commercially in the form of dry powder and are said to be more suitable for flocculating suspended solids (Li, 2005). These are exemplified by polyacrylamide and polyacrylic acid. Analyzes of such flocculants indicate that they have high molecular weight, are effective at different pH, and have low charge density (Li, 2005). Also, they are cost-effective and possess high flocculating efficiency.
- These organic flocculants are harmful to both humans and the environments e.g. polyaluminium chloride can induce Alzheimer’s disease.
- They are non-degradable.
- Large quantity of synthetic flocculant are needed.
- Toxic to the environment by generating secondary pollution.
These are exemplified by chitosan, gelatin, starch, cellulose and sodium alginate. These naturally occurring flocculants from renewable biomass are safe and biodegradable, cheap and non-toxic, but show weak activity in application (He et al., 2002). This natural flocculant also includes the bioflocculants.
The use of bioflocculants in waste water treatment seems to constitute not only safe but also economical alternatives to physical and chemical treatments (Ugbenyenet al., 2012). Bioflocculants are therefore capable of removing inorganic and organic particles through their flocculating activity. It has been investigated that bioflocculants is effective in removing suspended solids, heavy metals and bacteria and in reducing the turbidity of different types of industrial waste water effluents (Kuraneet al., 2011).
This research is aimed at accessing the production and characterization of bioflocculant using consortium organisms isolated from eatery waste water
- To producebioflocculant from the isolated species and consortium bacteria.
- To compare the flocculating activity of single species and consortium bacteria.
- To extract the bioflocculant produced from the broth medium.
- To characterized the produced bioflocculant.