Closed wastewater system in the tapioca industry in vietnam

Abstract

Wastewater from tapioca processing factory containing high COD (11,077-19,083 mg/l), SS (4,180-7,600 mg/l) and low pH (4.33-5.60) still causes heavy pollution to receiving water in South Vietnam. Closing the water circuit in the tapioca industries represents a very attractive option for eliminating pollution problems and the reuse of treated wastewater and solid wastes. The investigated and presently occasionally already implemented system consists of primary sedimentation tank, anaerobic treatment using UASB-reactors, aeration tanks using attached growth reactor and oxidation ponds system. Under laboratory conditions, organic loading rates applied in UASB-reactors are up to 40,35 kg COD/m3.d with treatment efficiency of 90-95%, reducing the COD concentration from up to 13,449 mg/l to 624-780 mg/l. The final effluent COD (sol.) after treatment in the pond system operated at hydraulic retention time of 12-20 days is lower than 10 mg/l. This effluent is suited very well either for use in agriculture or in the factory.

Cyanide removal from cassava mill wastewater using Azotobactor vinelandii TISTR 1094 with mixed microorganisms in activated sludge treatment system

“…These organic pollutants originate from the washing and extracting processes in the tapioca 16 -industry [30,31]. In order to produce 1 ton of starch, a tapioca processing factory discharges about 12 m 3 of wastewater containing 6125-13,500 mg l −1 (COD), 1466-7600 mg l −1 (SS) and pH 4.5-5.0 [32,33]. These values indicate that the wastewater is highly biodegradable and therefore, there is no need for the supply of external organic carbon source for cyanide-degrading microoganisms.…”

Clean technology for the tapioca starch industry in Thailand

“…According to the study of Tanticharoen and Bhumiratanatries [2], the generation of wastewater at the tapioca starch plants averages 20 m 3 for every ton of starch being produced. Similarly, Hien et al [3] reported the characteristics of wastewater from the Vietnam tapioca starch plants with the values of 11,000-13,500 mg COD/l, 4200-7600 mg SS/l, and pH of 4.5-5.0. The approximate generations of wastewater and solid waste (fibrous residue and peel) are 12 m 3 and 3 kg per ton of starch, respectively.…”

Cassava pulp enzymatic hydrolysis process as a preliminary step in bio-alcohols production from waste starchy resources

“…Thailand has 92 tapioca processing plants with a total production capacity of native and modified starch of about 16,910 and 4350 tonne (metric ton or Mg)/day, respectively, from cassava roots (Chavalparit and Ongwandee, 2009). However, processing one tonne of cassava roots generates around 3 m 3 of cassava wastewater (CWW) and 150 kg of cassava solid waste (CSW) (15% (w/w) of raw material) (Hien et al, 1999). Cassava roots are currently produced an average of around 25e30 million tonnes of per year, with for example 26,411,233 tonnes in 2007 (Cardona et al, 2010), this generates around 3e5 million tonnes of CSW and roughly 75e90 Â 10 6 m 3 of CWW annually from the cassava starch industry.…”