Application of bioflocculant-producing bacteria, heterotrophic nitrogen-removal bacteria, poly-phosphate bacteria and water-hyacinth (Eichhornia crassipes) for wastewater treatment of My Tho rice-noodle factories, Tien Giang province, Vietnam
Abstract
Rice-noodle wastewater represents a serious problem regarding environmental degradation and human health protection. The aim of the study was to create the application of bioflocculant-producing bacteria, heterotrophic nitrogen-removal bacteria, poly-phosphate bacteria and water hyacinth (Eichhornia crassipes) for wastewater treatment of My Tho rice noodle factories, Tien Giang province, Vietnam in order to get an insight into number of entities that discharge polluted water into environment. An experiment was carried outwith containers having different capacities from 100-mL, 1-L, 10-L, 100-L and 1000-L and 3 replications to select best strains of bioflocculant-producing bacteria, heterotrophic nitrogen bacteria, poly-P bacteria and water-hyacinth for removing toxic element to wastewater before releasing to river/canal. Application of two bioflocculant-producing bacterial strains PO.01.C and PRO.03.B (protein and polysaccharide) into rice-noodle wastewater, aeration in 3 hours, held on 21 hours, supernatant moved to other container, adding heterotrophic nitrogen removal bacterial strain and poly-P. strain 064.B, aeration 8 hr/24hr during 7 days and wastewaters were transferred other containers containing water-hyacinth (Eichhornia crassipes) in 2 days, the results recorded that pH of wastewater increased from 4.68 to 6.13, TSS and BOD concentration of wastewater reduced from 369 and 1200 mg/L to 17 5 and 23 mg/L, respectively. TKN and TPdecreased from 45 and 6.3 mg/L to 7.57 and 4.56 mg/L, respectively. All targets reached to 40/2011 standard / Ministry of Natural Resource and Environment of Viet nam.
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Introduction
Rice noodles are the most consumed form of rice product next to cooked rice grain in Asia [1]. Noodles may either be served by frying and mixing with vegetables and meats or served as a soup noodle by boiling in a broth. Rice protein lack gluten; hence lack the functionality of continuous visco-elastic dough.
My Tho city, a city locates in the Mekong Delta, Vietnam, has many traditional technologies and “My Tho rice noodle” is among famous technology for along time. Rice noodle has been produced from special local rice variety and there are seven manufacture factories have gathered in a cooperative and they have a “HU TIEU MY THO” trademark. However these factories work in the traditional condition therefore they have no wastewater treatment plant and wastewater have irrigated to canal or river directly. Especially wastewater from rice noodle factories contain many toxic elements as ammonium, orthophosphate,… and high TN, TP, BOD , TSS concentrations [2]. 5 Wastewater generated from these industries depicts wide variation in strength and characteristics. Variation due to the amount of water usage, type of vegetable and fruits used type of product and different additives like salt, sugar, gelatin, colors, oil and preservatives added also leads to the pollution load in the wastewater but this wastewater is nontoxic in nature because it comprises less hazardous compounds. Almost 50% of the water utilized in food processing industry is for washing and rinsing purposes. Water being the primary ingredient is widely used as a cleaning agent in food processing industry [3]. After cellulose, starch is the second polysaccharide found in nature, produced by plants as reserve material. The main cultivated actually plants for the starch industrially production are cereals, especially corn, followed by wheat and potato [4]. Generally, rice noodles are made from flour containing high amylose concentration (> 22%), which contributes to the gel network. It provides firm structure and desirable properties to noodle [1,5]. There is significant association found between amylose and acceptability of rice noodles [6].
Physicochemical wastewater treatment is a frequently used technique in the area of wastewater treatment [3]. Physicochemical wastewater treatment techniques are applied for the removal of heavy metals, oils and greases, suspended matter and emulgating organic substances, organic and inorganic components, difficult to decompose, nonpolar organic substances, toxic pollutants or high salt concentrations, phosphorus [7].
Under food processing industry, Palm oil refining wastewater has been successfully treated by physicochemical treatment using chitosan, alum and PAC and reported [8].
Flocculants are divided into inorganic flocculants such as aluminium sulfate (Alum) and polyaluminium chloride (PAC), organic synthetic high polymer flocculants such as polyacrylamide (PAA) derivatives, polyacrylic acids and polyethylene imine and naturally occurring bio-polymers flocculants such as chitosan, sodium alginate and microbial flocculants or bioflocculant [9,10,11]. Bioflocculant is a kind of biodegradable macromolecular flocculant secreted by microorganisms. Because of their biodegradability, harmlessness and lack of secondary pollution, bioflocculants have gained much wider attention and research to date [12]. Most of research focused on screening for microorganisms, culture conditions, mechanism of flocculation, chemical structure, and so on [13,14,15,16,17].
The aims of this study were (i) applying bioflocculant-producing bacteria to reduce organic and inorganic components, (total suspended solids = TSS) (ii) using heteroytophic nitrogen removal bacteria and poly-phosphate bacteria to decrease total kjeldahl nitrogen (TKN) and Total phosphorus (TP) and (iii) application of water hyacinth to remove or reduce (Bio-Oxygen Demand) BOD concentration in wastewater reaching to 40:2011 standard of Ministry of Natural Resources and 5 Environment Vietnam.
Conclusion
Application of bioflocculant-producing bacteria, heterotrophic nitrogen removal bacteria, poly-P bacteria and water-hyacinth treated My Tho rice-noodle wastewater effectively and safety. 40/2011 Standard (B level)
Bacterial Treatment Initial control Ministry of Natural Resource and application* Environment pH 4.89 5.71 6.13 5.5 – 9.0 Total of Suspended Sodids (TSS) mg/L 369 31 17 100 Biological Oxygen Demand (BOD ) mg/L 1200 200 23 50 5 Total Kjeldahl Nitrogen (TKN) mg/L 45.0 120 7.57 40 Total Phosphorus (TP) mg/L 6.3 7.57 4.76 6.0
