The Application Of The Hybrid Coagulation/Flocculation Process With Membrane Filtration

Water is one essential source for human being and other living creatures on earth. It becomes one necessary problem that how to obtain clear and safety drinking water for the whole world. Contamination on drinking water because of inadequate sanitation is a major risk factor for health problems. At least 10% of diseases that include 4 million cases of diarrhea annually which cause at least 1.8 million of deaths. Particularly Giardia and Cryptosporidium species are a big problem due to their wide distribution in the environment and high resistance to the conventional water treatment process. Outbreaks of this parasitic protozoans have been reported worldwide so is it necessary to find a way to eliminate them by using new methods or improving the current ones.Coagulation/flocculation process is one important operation unit during water treatment. Coagulation/flocculation process is so complex. There are too many influence factors, such as, the characteristics of the water source, raw water p H, alkalinity and temperature, the type of coagulant and coagulant aids and their order of addition, dose rates of coagulants, the degree and time of mixing provided for chemical dispersion and flocs formation. Two common inorganic coagulants are usually used during water treating process, alum-coagulants or ferric-coagulants. However, they both have some disadvantages, alum-coagulants facing the question that residual aluminum concentration may be harmful to human and animals, and ferric-coagulants facing the problem that affecting the colority of raw water easily.The use of natural polyelectrolytes such as Chitosan and seeds of Moringa oleifera could be an option with many advantages over chemical agents, especially because of his biodegradability, low toxicity, and low residual sludge production and less risks of health. Paper aimed on the review of characterization and application of Chitosan and seeds of Moringa oleifera.There are lots researches and studies about the application of Chitosan. Moringa seeds contain a non-toxic natural organic polymer which is an active agent with excellent activity and coagulating properties. The Moringa seed has a protein that when solubilized in water is able to promote coagulation and flocculation of compounds that cause color and turbidity in highly turbid water. The problem is that the use of coagulants for drinking water treatment is usually not able to generate water of high potability standards and this is why is necessary to have a simultaneous technique such as the membrane filtration technique.Membrane filtration is a pressure-driven separation process that use semipermeable membranes this are like physical barriers that are able to remove suspended particles and colloids, turbidity, bacteria, algae, parasites and viruses for clarification and disinfection purposes. Paper focused on the contents about the concept of membrane filtration, materials of membranes, classification of operation process. In recent years, membrane filtration, as one efficient technique, has been used widely during water treating process. There four types of membrane filtration commonly seen, micro-filtration(MF), ultra-filtration(UF), nano-filtration(NO) and reverse osmosis(RO). Membranes are advanced pre-treatments that in recent years have become more important due the negligible amounts of chemicals used.In recent years the use of MF/UF membranes has rapidly increased in the field of drinking water production. Stricter drinking water regulations and requirements for the treatment are creating a rapid growth in the use of this membranes to treat more challenging water sources. The filtration with porous membranes is a young, but worldwide quickly expanding technology in the drinking water production.Membrane fouling is the process in which a solution or a particle is deposited on the membrane surface or inside the membrane pores and this generated a degradation of the membrane performance. Fouling is a major obstacle to the use of the membrane technology because severe fouling may require intense chemical cleaning or membrane replacement which increases the operation costs of a treatment plant. There are various types of foulings: colloidal, biological, organic and scaling.One of the major problems in treating water for drinking water is the high content of natural organic matter(NOM). NOM in the water causes odour influences the taste, increases the corrosion and biofilm growth in the distribution network. The removal of NOM is one of the most important treatment requirements for the production of drinking water, because is so hard to remove successfully with conventional treatment processes. NOM also is considered one of the main causes of fouling of membranes. The originic of all. Therefore, it is necessary to find or research one excellent technology to remove NOM with high efficiency.The use of membranes in China has been utilized to treat municipal and industrial water and natural coagulants has been used for many years but the combination of both methods hasn’t been prove yet or at least is not easy to find this information. China has severe pollution problems and scare of water in the north part of the country and accounts only 7% of the globes freshwater resources so to treat drinking water is a major deal for the Chinese Government.In comparison Brazil has many freshwater resources but in cities like Rio de Janeiro they are dealing with pollution. In recent years the Government of Brazil has encourage the investigation to treat drinking water and there has been investigations about the hybrid coagulation/flocculation process(CF-MF/UF technology) using natural coagulants in association with membrane filtration process(MF/UF) to treat Giardia and Cryptosporidium. There are different types, such as, coagulation/flocculation using chitosan as coagulant followed by ultrafiltration(CFQ-UF) and coagulation/flocculation using Moringa oleifera as coagulant followed by microfiltration(CFM-MF). The use of this new technique can help to clean the drinking water and reduce health problems that the people are having because of the use of chemical coagulants.Paper focused on the review of coagulation/flocculation and membrane filtration during water treatment process. Summarized some classification of coagulants/flocculants which are commonly used in treating process. Pointing out that natural materials, such as Chitosan and seeds of Moringa oleifera could be considered as coagulants to pure water resource. And those natural coagulants combined with membrane filtration to form one hybrid treating technique, so that to improve the efficiency of treating performance, such as reducing Giardia and Cryptosporidium species, and NOM during water. Viewing from the comparison of technologies between China and Brazil, author thinks China could borrow ideas from Brazil, to advance those water treating techniques.