Dairy wastewater treatment

Membrane Filtration as an Alternative to Conventional Dairy Wastewater Treatments.528... 

RO, primarily used ia the dairy iadustry, is expanding iato other areas of food processiag. RO can be used for a variety of operations, ranging from wastewater treatment and material recovery to clarification and concentration. Material recovery is advantageous for two reasons. By recovering valuable products, eg, proteias, from waste streams, profits can be iacreased while costs for waste disposal decreased. An excellent review of the different apphcations ofRO ia food processiag is available (9). 

Vourch et al49 studied the applicability of the RO process for the dairy industry wastewater. The treated wastewater total organic carbon (TOC) was <7 mg/L. It was found that in order to treat a flow of 100 m3/d, 540 m2 of the RO unit is required with 95% water recovery. Dead-end NF and RO were studied for the treatment of dairy wastewater.50 Permeate COD, monovalent ion rejection, and multivalent ion rejection for the dead-end NF were reported as 173-1095 mg/L, 50-84%, and 92.4-99.9%, respectively. When it comes to the dead-end RO membranes, the values for permeate COD, monovalent ion removal, and multivalent ion removal were 45-120 mg/L, >93.8%, and 99.6%, respectively. Membrane filtration technology can be better utilized as a tertiary treatment technology and the resultant effluent quality will be high. There can be situations where the treated effluents can be reused (especially if RO is used for the treatment). 

Sengil, I.A. and Ozacar, M., Treatment of dairy wastewaters by electrocoagulation using mild steel electrodes, Journal of Hazardous Materials, 137 (2), 1197-1205, 2006. 

The wastewater treatment is widely applied for industrial (e.g., food [23], beverage [24], dairy industry [25], municipal [26, 27]) as well as domestic wastewater. 

TABLE 3.9 Anaerobic/aerobic treatment performance levels for dairy wastewaters (Demirel et al., 2005)... 

Backman, RC, Blanc, FC, and O shaughnessy, JC (1985). Treatment of dairy wastewater by the anaerobic up-flow packed bed reactor. In "Proceedings of 40th Purdue Industrial Waste Conference" pp. 361-372. 

Demirel, B., Yenigun, O., and Onay, T. T. (2005). Anaerobic treatment of dairy wastewaters A review. Process Biochem. 40, 2583-2595. 

Kasapgil, B., Anderson, G. K., and Ince, O. (1994). An investigation into the pretreatment of dairy wastewater prior to aerobic biological treatment. Water Sci. Technol. 29, 205-212. 

Protein-rich wastewaters have been reported in the food industry [108] and dairy industry [109]. The amino acid rich wastewaters have been reported in the amino acid producing industry [110]. Most literature references, up to date, deal with the treatment of dairy wastewater(s). Dairy wastewaters are produced at different rates and with different composition depending on the type of dairy product and the intensity ot the production campaign [109]. Physical, chemical, and biological parameters of the dairy wastewaters change from one plant to another and in between individual production batches and also depend on the technology used in production [111]. 

Organic carbon is accounted for by lactose, fats, and proteins [112-114]. To a hmited extent, protein and fat loading can be removed using precipitation [115]. Practical problems with precipitation arise from the low removal efficiencies, as well as from the need for expensive reagents [109]. Casein accounts for 80% of total protein in dairy wastewaters, and hydrolysis is the main biodegradation mechanism regardless of the concentration of oxygen, that is, whether anaerobic or aerobic treatment methods are used... 

Figure 7.44 shows the typical dependence at steady state of substrate and product concentrations, and of productivity on permeate flow rate, i.e., dilution rate, for lactose fermentation to ethanol by Kluyveromices fragilis in a cell recycle membrane fermentor.89 As dilution rate increases fermentor productivity increases, attains a maximum value and then decreases. Product and substrate concentrations in the permeate, instead, steadily decrease and increase, respectively, as dilution rate increases. A compromise generally has to be made between production rate and product concentration in the effluent. When the absence of substrate in the permeate is required, it obviously limits fermentor productivity, as in the case of wastewater treatment in the dairy industry. On the other hand, low substrate concentrations in the permeate keep recovery... 

Leal MCMR, Cammarota MC, Freire MG et al. (2002) Hydrolytic enzymes as coadjuvants in the anaerobic treatment of dairy wastewaters. Braz J Chem Eng 19(2) 175-180 Leisola M, Turunen O (2007) Protein engineering opportunities and challenges. Appl Microbiol Biotechnol 75(6) 1225-1232... 

Fouling, which causes flux decline, remains to be the biggest concern in treating dairy wastewater by membrane separation. Various pretreatment procedures have been studied to minimize this problem. In pilot-scale wastewater treatment, Sarkar et al. [187] investigated the clariflcation of dairy wastewater by chitosan treatment (10 mg L" at pH 4.0) to... 

Characteristics of membrane modules are summarised in Table 1.12. The spiral wound (SW) module shown in Figure 1.18 is used in all RO and NF applications. The RO hollow-fibre (FIF) module, similar to the one shown in Figure 1.19, is now manufactured by only by Toyobo, and is used for seawater desalination. UF HF membrane (see Figure 1.3) was used extensively in the dairy industry, but it has largely been replaced by SW modules. However, cross-flow HF modules are commorJy used in food processing and industrial wastewater treatment [18, 31]. 

PHAs can be produced from waste materials. Waste materials or wastewater may be used to produce PHAs with a reduction in cost. The production of PHB from the waste-activated sludge generated by a combined dairy and food processing industry wastewater treatment plant has been evaluated. Deproteinized jowar grain-based distillery spentwash yielded 42.3 wt% PHB, followed by filtered rice grain-based distillery spentwash, which yielded 40wt%PHB. 

Namasivayam, C. and Ranganathan, K. 1992. Waste Fe(III)/Cr(III) sludge as flocculant for the treatment of dairy wastewater. Bioresour. Technol. 40 209-213. 

Rajinikanth Rajagopal (sustainable agro-food industrial wastewater treatment). Dairy and Swine Research and Development Centre, Agriculture and Agri-Food Canada, Quebec, QC... 

Poly(vinylidene fluoride) (PVDF) is one of the promising polymeric materials that has prominently emerged in membrane research and development (R D) due to its excellent chemical and physical properties such as highly hydrophobic nature, robust mechanical strength, good thermal stability, and superior chemical resistance. To date, PVDF hollow-fiber membranes have dominated the production of modem microfiltration (MF) ultrafiltration (UF) membrane bioreactor (MBR) membranes for municipal water and wastewater treatment and separation in food, beverage, dairy, and wine industries. In the last two decades, increasing effort has been made in the development of PVDF hollow fibers in other separation applications such as membrane contractors [6,7], membrane distillation (MD) [8-11], and pervaporation [12,13]. 

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