Skip to main content
NCBI home page
Journal of Food Science and Technology logoLink to Journal of Food Science and Technology
. 2022 Sep 12;60(1):84–91. doi: 10.1007/s13197-022-05590-2

Combination of chemical coagulation and membrane-based separation for dairy wastewater treatment

Airton C Bortoluzzi 1,2, Carolina E Demaman Oro 2, Maicon S N dos Santos 3, Marcelo L Mignoni 2, Rogério M Dallago 2, Juliana Steffens 2, Marcus V Tres 3,✉
PMCID: PMC9813288  PMID: 36618061

Abstract

An important factor resulted from the ascension of the milk and milk-based by-products production is many effluents directly released into the environment. The main objective of this study was to evaluate the efficiency of the combination of the chemical coagulation, with ferric chloride as a coagulant, and the membrane separation processes (MSP) and reverse osmosis (RO) processes in the treatment of effluents from a powdered milk dairy industry. To evaluate the effectiveness of the integration of these mechanisms, the characterization of the effluents was carried out through Total Nitrogen (Ntotal), Total Organic Carbon (TOC), Chemical Oxygen Demand (COD), color, pH, and turbidity analysis. Regarding the treatments with ferric chloride, the Ntotal removal was up to 55.7% (concentration of 1.2 g L− 1) and the color up to 50% (0.7 g L− 1). For the MSP and RO treatments, the color removal was up to 100% (1st RO), turbidity up to 100% (1st RO), COD up to 98.7% (3rd RO), and TOC up to 96.7% (3rd RO). Finally, the integration of the chemical coagulation and MSP processes was efficient for the treatment of dairy industry wastewater and provides the return of water in appropriate characteristics according to legislation.

Keywords: Coagulation, Dairy, Ferric chloride, Microfiltration, Reverse osmosis, Wastewater

Introduction

The population expansion noticed in recent years delineates the impulse in food demand from global perspectives. According to the Food and Agricultural Organization (FAO), it is necessary the worldwide food production to double the current level by 2050 to satisfy human nutritional requirements (FAO 2019). In this context, the dairy industry is fundamental for the agricultural scenario, mainly due to the high demand for milk and milk-based products worldwide. To satisfy the requirements of the supply chain, world milk production is up to 730 million tons annually and projections indicate an increase of up to 23% by 2025 (Grout et al. 2020). Nonetheless, an important factor associated with this situation is many effluents directly released into the environment. It is estimated that 4–11 million tons of industrial dairy waste are released into the environment every year (Ahmad et al. 2019). This panorama reflects discouraging perspectives due to the expansion of the volumes generated, revealing a serious risk to be considered in the coming years.

Direct milk production and processing that involves obtaining milk-based by-products generates about 1–10 m³ of wastewater per m³ of processed milk. Consequently, the intensification of residual quantities from dairy industries present in the environment has become a disturbing factor for public health and the environment. Although the expansion of production benefits food security, this scenario is an alarming threat to the stability of ecosystems (Grout et al. 2020). Dairy wastewater has guided the degradation of the environment and human health since contamination by these materials results in a devastation of the local biodiversity and high risks of microbial spread (Ahmad et al. 2019). Residual water has a high organic load and high concentrations of nutrients (Gil-Pulido et al. 2018). Additionally, it presents a high polluting potential, since it rejects large concentrations of organic matter and numerous microorganisms for the environment (Nabbou et al. 2020). Moreover, these materials indicate high biological oxygen demand (BOD) and chemical oxygen demand (COD) in the medium (Gil-Pulido et al. 2018).

Conventional liquid effluent treatments used in the dairy industries essentially involve biological and physicochemical approaches. Biological treatments, especially aerobic methods, generate large volumes of activated sludge due to the water biodegradability, additionally to exploring water resources that occupy large areas and operate through microbiological degradation, which demands ideal conditions to achieve the necessary treatment efficiency (Rufus et al. 2019). Furthermore, considering the characteristic conditions of wastewater, this strategy promotes high economic consumption (Abdelfattah et al. 2020). Also, the exploration of other procedures and technologies has been reported, specifically about the usual physicochemical processes, such as decantation, filtration, and coagulation/flotation (Cruz et al. 2020).

The coagulation process is reported as one of the main processes applied in the treatment of industrial wastewater, essentially due to its effectiveness in eliminating undesired particles, organic compounds, microorganisms, metallic substances, etc. (Prakash and Garg 2016). The main coagulants used are aluminum and iron salts, mainly because they are low-cost products. Aluminum sulfate has an effective pH range in the clotting process between 5.0 and 8.0. The flocs resulting from coagulation with sulphate are essentially inorganic, therefore, the sludge does not undergo biological decomposition, that is, it is not biodegradable, making its final disposal difficult. The low one, and is ferric, for having a wide pH range between 11.0, which makes an advantage in a coagulation range provides a wider range without the need for pH correction to make effluent. As ferric chloride has a low solubility of the formed ferric hydroxides, they can act over a wide pH range between 5.0 and 11.0, which makes it an advantage for providing coagulation in a wider range without the need for pH correction (Li et al. 2017).

As reported in Fig. 1a, the minimization of these materials is accomplished through the application of coagulants that provide the disequilibrium and neutralization of particles present in the aggregates, facilitating their removal (Precious Sibiya et al. 2021). These aggregates are rapidly eliminated by some procedures, such as sedimentation, filtration, or flotation. Physicochemical attributes such as color, turbidity, and COD are extremely relevant to the characterization of wastewater and are significantly reduced through the direct action of coagulants (Bouchareb et al. 2020).

Fig. 1.

Fig. 1

Open in a new tab

Schematic representation of the coagulation and aggregate generation process (a) and the complex of the processes involving filtration membranes and reverse osmosis (b)

Further strategies have been widely implemented in wastewater treatment processes, such as the membrane separation process (MSP). This technique provides a significant improvement in water quality after the filtration process, as well as minimizing energy costs and reducing sludge production (Ensano et al. 2016). Fundamentally, the use of membranes is closely related to the selectivity of determined substances, in which compounds denominated permeates penetrate the membrane through physical parameters, such as pressure gradient, concentration gradient, temperature gradient, and electrical gradient, and the retained compounds are fractions that do not cross the membrane (Biniaz et al. 2019) (Fig. 1b). Nevertheless, the specific use of membranes without other additional processes causes a high accumulation of proteinaceous materials on the membrane surface, forming an obstruction for the direct treatment of wastewater and preventing the maximum potential for waste filtration. This scenario is variable depending on the physicochemical particularities of each membrane (source material, pore size, surface tension, etc.), characteristics of the effluent, and the performance of the pre-treatment units (Meiramkulova et al. 2020).

The integration of processes involving the application of membranes with different promising strategies, such as coagulation, has been widely implemented and attests to encouraging results regarding the treatment of wastewater (Ezugbe and Rathilal 2020). The combination of nanofiltration and chemical and bio-coagulant membranes (aluminum-chloride, iron-chloride, polyaluminium chloride, and processed Moringa oleifera powder (PMOP)) removed turbidity to up to 99.9%, COD to 99.5%, and color to 99.5% (Bouchareb et al. 2020). A similar study using M. oleifera as a natural coagulant and succession of microfiltration and nanofiltration membranes showed removal efficiency of up to 96% to COD, 99% to color, and 99% to turbidity, evidencing the viability of the aggregation of these processes (Mateus et al. 2017).

The objective of this study was the application of combined processes of chemical coagulation with ferric chloride and membranes of microfiltration and reverse osmose on the remotion of color, turbity, nitrogen, total organic carbon and chemical oxygen demand of effluent from the powdered milk dairy industry.

Methods

Effluent

Raw wastewater was obtained from a dairy company located in the North of Rio Grande do Sul State − Brazil. The effluent was collected immediately after the equalization tank. The samples were collected, homogenized, and stored at − 18 °C. For each experiment, a quantity of sample was thawed at room temperature (22 °C) and filtered on 25 μm quantitative filter paper (J Prolab, model JP40).

Primary treatment with ferric chloride

The primary treatment was carried out with the addition of ferric chloride in the raw effluent. First, the pH was adjusted to 11.0 with 1 M sodium hydroxide (NaOH) and 0.5 to 2.0 g L−1 of ferric chloride was added to the effluent. The mixture was slowly stirred for 3 min at room temperature, followed by decanting for 120 min. Finally, the effluent was filtered on 25 μm filter paper (J Prolab, model JP40). The choice of the best final ferric chloride concentration was made based on the best result obtained for the parameters of color, pH, Total Organic Carbon (TOC), and Total Nitrogen (Ntotal).

Membranes

After the primary treatment with ferric chloride, the effluent was subjected to filtration with membranes, with the experimental apparatus described according to Bortoluzzi et al. (2017). The microfiltration membrane (MF) was a hollow-fiber-type polymeric membrane (PAM Membranas Seletivas Inc., Brazil) composed of a poly(ether sulfonate)/poly(vinyl pyrrolidone) (PES/PVP) mixture with a 0.20 μm pore diameter. The reverse osmosis membrane (RO) was composed of polyamide composites (Dow-Filmtec, Canada) with an area of 0.0034 m², with rejection > 99.5% NaCl (2 g L−1 NaCl at 4.8 bar and 25 °C).

First, the pressure of 1 bar was applied to the MF membrane, and the pressure of 20, 15, and 10 bar was varied on the RO membrane to increase the rejection by reducing the pressure (flux rate = 9 mL min−1 at 25 °C). The process carried out is also known as the process of separating membranes in stages, with each filtration representing a stage. Thus, double (MF + RO), triple (MF + R + RO) and quadruple (MF + RO + RO + RO) filtration stages were applied. The performance of the membranes was measured in terms of the permeate flux (JP, L h−1 m−2), given by the ratio between the permeate flux (Q, L h−1) and the membrane filtration area (A, m2) (de Melo et al. 2015). Conditioning and cleaning of the membranes were carried out according to previously established methodology (Bortoluzzi et al. 2017).

Analytical determinations

The effluent samples before and after treatment were analysed according to Standard Methods for the Examination of Water and Wastewater (APHA 2005). The color was measured using a colorimeter (HACH, model DR870) at room temperature (25 ± 1 °C) at a wavelength of 420 nm. The result was given in mg Pt–Co L− 1. Turbidity was determined using the 2130 B method, using a colorimeter (HACH, model DR870) at room temperature (25 ± 1 °C) at a wavelength of 720 nm. The result was given in Formazina Attenuation Units (FAU) that measure the decrease in transmitted light through the sample at an angle of 180 degrees to the incident light. The pH was determined at room temperature (25 ± 1 °C) with a potentiometer (Metrohm, model 827 pH lab), calibrated with buffer solutions of pH 4.0, 7.0, and 10.0 (Vetec). pH of the raw effluent in the present study was adjusted to 11.0 before going through any process step.

For the analysis of Total Organic Carbon (TOC) the sample was prepared from an effluent aliquot of 1 mL, previously filtered through a membrane (0.45 μm) and diluted to 25 mL with distilled water. Subsequently, analyzed by a TOC analyzer equipment (SHIMADZU, TOC-TOC-VCSH). Determinations were carried out by catalytic oxidation at high temperature (680 °C). The TOC content was determined by the difference between the concentrations of total carbon and inorganic carbon. Results were expressed in mg L− 1. For the Ntotal analysis, the samples were prepared from a 1 mL effluent aliquot, previously filtered through a membrane (0.45 μm) and diluted to 25 mL with distilled water. Subsequently, analyzed by an Ntotal analyzer equipment (SHIMADZU, TOC-TOC-VCSH). Determinations were carried out by catalytic oxidation at high temperature (720 °C). Results were expressed in mg L− 1. Conductivity was measured directly on the sample using a portable digital conductivimeter (model LF 191, WTW). The unit of conductivity was expressed in μS cm−1. Chemical Oxygen Demand (COD) was determined using the 5220 D method, that employs standard solutions of potassium acid phthalate, acid solution (Ag2SO4 in concentrated H2SO4) and digester solution (composed of K2Cr2O7, HgSO4 and H2SO4 diluted in water) as reagents. ). The method consists of the reduction of chromium (Cr6+ to Cr3++) and subsequent analysis through color modification in a spectrophotometer. The digestion of the samples was carried out in a thermoreactor (DRY BLOCK MA 4004, Marconi) at 150 °C for 2 h. After cooling the samples, the readings were performed in a digital colorimeter (HACH, DR870) previously calibrated with standard solutions of potassium acid phthalate. Results were expressed in mg L− 1.

Results and discussion

Primary treatment with ferric chloride

The primary treatment was conducted with the addition of 0.5 to 2.0 g L−1 of ferric chloride, and the results obtained are shown in Fig. 2. From the results obtained, it was possible to define the best concentration of ferric chloride in terms of removal of TOC in contrast to the increase in color. Analysing the data presented in Fig. 2, there is a constant reduction in pH with an increase in the concentration of coagulant. A decrease in TOC and Ntotal up to 0.7 g L−1 of ferric chloride is observed, and after this concentration, stability in the results is observed. The concentration of 0.7 g L−1 was also the one with the lowest color index, suggesting that it is the best concentration for the effluent under study.

Fig. 2.

Fig. 2

Open in a new tab

Results of a color and pH (line) and b Ntotal and TOC (line) of the effluent with the addition of different concentrations of ferric chloride coagulant

Sarkar et al. (2006) tested the pH equal to 4.0, 6.5, and 8.0 for the addition of ferric chloride in a dairy effluent, with agitation for 5 min, and subsequent decantation for 120 min, where the authors did not observe coagulation with this range of pH. The authors verified that the alkaline environment favors the formation of hydroxides and positively charged mono and polynuclear species, which combine with the negatively charged colloidal particles present in the evaluated dairy effluent. Given the results presented by these authors, the pH of the raw effluent in the present study was adjusted to 11.0 before going through any process step. Like that found in the present study, other authors have shown that the pH decreased and become acidic employing ferric chloride in the dairy wastewater treatment (Kurup et al. 2019).

From the data presented, the concentration of 0.7 g L−1 of ferric chloride was considered as the optimum point for the coagulation of the effluent as the primary treatment to be applied before the MSP.

Membrane separation process

The first combined treatment consisted of treating the primary effluent with the microfiltration membrane (MF). Figure 3a shows the results of permeate fluxes over time, at a constant pressure of 1 bar. There was polarization by concentration and the polarization stabilized after 40 min of filtration.

Fig. 3.

Fig. 3

Open in a new tab

a Permeate fluxes from the MF at 1 bar feed with primary effluent and b permeate fluxes from the first, second and third sequential filtration with the RO membrane at 20, 15, and 10 bar, respectively

The permeate from the MF fed the RO membrane at 20 bar, after the permeate fed the RO at 15 bar and, subsequently, the permeate fed the RO at 10 bar. The fluxes in RO with time at each pressure were kept constant, as shown in Fig. 3b. This behavior was like that found by Turan (2004), who observed a decline of only 5 to 10% in the RO permeate flux during 3 to 4 h of filtration of dairy effluent using spiral polyamide composite membranes with pressures between 6 and 18 bar.

The results of the analytical determinations carried out on the raw effluent, and after the primary treatment and with the MF and RO membranes are shown in Fig. 4.

Fig. 4.

Fig. 4

Open in a new tab

Results of a color and turbidity (line) and b COD and TOC (line) of the effluent with different treatments

As shown in Fig. 4a, there was a decrease in color from 1800 ± 0.01 mg Pt–Co L–1 to 75 ± 0.07 mg Pt–Co L−1 of the raw effluent for the treatment after the MF. The color had its equal to zero after the RO membrane. The turbidity also showed a sharp drop in its values, starting at 308.3 ± 0.03 FAU and presenting 50 ± 0.07 FAU after the MF membrane, also equaling its value to zero after the RO. The color and turbidity showed the same behavior, with significant decreases after the use of primary treatment and MF and after RO.

COD and TOC also showed a significant decrease in their values, as shown in Fig. 4b. 254.67 ± 1.10 mg L–1 was achieved for COD in the permeate of the first RO. This is much higher than the 16.5 mg L–1 obtained by Sarkar et al. (2006) applying combined treatment (primary + MF + RO). This may be due to the raw dairy effluent used by the authors, which had compounds with higher molecular weight. This can increase retention in filtration with membranes.

The removal efficiencies of the present study are shown in Table 1. It is possible to see that the removal efficiency of color, turbidity, COD and TOC using coagulant (1st treatment) was lower compared with the other process. Bortoluzzi et al. (2017) applying a double stage integrated filtration system (MF + RO) reduced 100% turbidity, 100% color, 94% total Kjeldahl nitrogen, and 84% total organic carbon in the dairy wastewater. Our study presented 100% turbidity removal in addition to 89.9 ± 0.10% TOC removal for the MF + RO system by applying the primary treatment. This result indicates that the use of primary treatment has a positive effect on the treatment of waste from the dairy industry. The parameters evaluated in Table 1 are within the recommended for disposal by current legislation (Conselho Nacional do Meio Ambiente - CONAMA, 2011). The results obtained in the present study showed that chemical coagulation followed by MSP (MF + RO + RO + RO) is effective for the treatment of dairy effluents, with the removal of up to 96.7 ± 0.10% in all tested variables.

Table 1.

The removal efficiency of the microfiltration membrane (MF) and reverse osmosis (RO) treatments

Variable Raw effluent After the coagulation/MSP processes Removal efficiency (%)
1st treatment MF 1st RO 2nd RO 3rd RO
Color (mg Pt-Co L− 1) 1800.0 ± 0.01 0 ± 0.0 25 ± 0.0 95.8 ± 0.0 100 ± 0.0 100 ± 0.0 100 ± 0.0
Turbidity (FAU) 308.3 ± 0.03 0 ± 0.0 48.6 ± 0.0 83.7 ± 0.0 100 ± 0.0 100 ± 0.0 100 ± 0.0
COD (mg L− 1) 3505.5 ± 0.09 43.6 ± 0.05 40.8 ± 0.05 47.5 ± 0.05 92.7 ± 0.05 98 ± 0.05 98.7 ± 0.05
TOC (mg L− 1) 554.8 ± 0.10 18.0 ± 0.01 11.4 ± 0.10 16.3 ± 0.10 89.9 ± 0.10 94.2 ± 0.10 96.7 ± 0.10
Open in a new tab

Electrical conductivity of 11.4 ± 0.10 and 2.8 ± 0.06 µS cm− 1 was observed in the second and third RO permeate, respectively. For comparison purposes, the electrical conductivities of tap water, distilled water, and Milli-Q water used in the Waste Treatment Laboratory were measured, obtaining 25.7 ± 0.21, 2.5 ± 0.04, and 0.9 ± 0.02 µS cm− 1, respectively. From these values, it appears that the permeate of the second RO has less conductivity than the tap water and the permeate of the third RO is similar to that of distilled water. This demonstrates the possibility of obtaining permeates consistently with drinking water in terms of electrical conductivity.

Regarding the concentrate obtained at the end of the PSM, the volume retained in the membranes and the residues from cleaning them can be released in the primary treatment, which generates residues that require periodic removal and proper disposal. Also, the sludge generated when using iron as a coagulant does not present any restrictions for its disposal in agricultural soil, since the soil itself is an iron oxide. In the soil, iron oxides are related to the adsorption of heavy metals, as well as in the fixation of phosphorus in soils, thus preventing their rapid leaching (Ceni et al. 2019).

Conclusion

Dairy industries represent an agricultural segment with excellent prospects and significant growth in the coming years. The demand for direct milk production and milk-based by-products stimulates the production and receives attention and innovation for its improvement. However, the wastewater generated by the milk production processes is an inconvenient factor that results in the degradation of the environment and an intense risk for human health since contamination by these materials induces the devastation of the local biodiversity and high risks of microbial spread. This scenario requires the adoption of effective treatment measures that allow the minimization of undesirable water characteristics and facilities to achieve the legislative standards for disposal and reuse.

Regarding the treatments with ferric chloride, the color removal was up to 50% (concentration of 0.7 g L− 1), Ntotal up to 55.7% (1.2 g L− 1), TOC up to 29.7% (0.7 g L− 1), and pH variation up to 59% (2.0 g L− 1). According to the MSP and RO treatments, the color removal was up to 100% (1st RO), turbidity up to 100% (1st RO), COD up to 98.7 ± 0.05% (3rd RO), and TOC up to 96.7 ± 0.10% (3rd RO). For this study, the application of combined processes (chemical coagulation + membrane separation) in the effluent of a dairy company was efficient to achieve the standards of disposal and reuse of the Brazilian Legislation.

Authors’ contributions

AC, RD, and JS conceptualized the study. All authors analyzed, interpreted the data and wrote the manuscript. All authors read and approved the final manuscript.

Funding

The authors thank URI Erechim, National Council for Scientific and Technological Development (CNPq) [Grants Numbers 308936/2017-5; 428180/2018-3; 306241/2020-0], Coordination for the Improvement of Higher Education Personnel (CAPES) [Grant Number 001] and Research Support Foundation of the State of Rio Grande do Sul (FAPERGS) [Grant Number 16/2551-0000522-2].

Data availability

Not applicable.

Code availability

Not applicable.

Declarations

Conflict of interest

The authors declare no conflict of interest.

Ethical approval

Not applicable.

Consent to participate

Not applicable.

Consent for publication

Not applicable.

Footnotes

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Contributor Information

Airton C. Bortoluzzi, Email: airton.bortoluzzi@erechim.ifrs.edu.br

Carolina E. Demaman Oro, Email: carolinae.oro@hotmail.com

Maicon S. N. dos Santos, Email: maiconsergions@gmail.com

Marcelo L. Mignoni, Email: mignoni@uricer.edu.br

Rogério M. Dallago, Email: dallago@uricer.edu.br

Juliana Steffens, Email: julisteffens@uricer.edu.br.

Marcus V. Tres, Email: marcus.tres@ufsm.br

References

  1. Abdelfattah A, Hossain MI, Cheng L. High-strength wastewater treatment using microbial biofilm reactor: a critical review. World J Microbiol Biotechnol. 2020;36:1–10. doi: 10.1007/s11274-020-02853-y. [DOI] [PubMed] [Google Scholar]
  2. Ahmad T, Aadil RM, Ahmed H, et al. Treatment and utilization of dairy industrial waste: a review. Trends Food Sci Technol. 2019;88:361–372. doi: 10.1016/j.tifs.2019.04.003. [DOI] [Google Scholar]
  3. APHA . Standard methods for the examination of water and wastewater. 21. Washington DC: American Public Health Association/American Water Works Association/Water Environment Federation; 2005. [Google Scholar]
  4. Biniaz P, Ardekani NT, Makarem MA, Rahimpour MR. Water and wastewater treatment systems by novel integrated membrane distillation (MD) ChemEngineering. 2019;3:1–36. doi: 10.3390/chemengineering3010008. [DOI] [Google Scholar]
  5. Bortoluzzi AC, Faitão JA, Di Luccio M, et al. Dairy wastewater treatment using integrated membrane systems. J Environ Chem Eng. 2017;5:4819–4827. doi: 10.1016/j.jece.2017.09.018. [DOI] [Google Scholar]
  6. Bouchareb R, Derbal K, Özay Y, et al. Combined natural/chemical coagulation and membrane filtration for wood processing wastewater treatment. J Water Process Eng. 2020;37:101521. doi: 10.1016/j.jwpe.2020.101521. [DOI] [Google Scholar]
  7. Ceni G, Dallago RM, Mores R, et al. Avaliação da eficiência do cloreto férrico como coagulante no tratamento de um efluente sintético pelo método convencional e eletrocoagulação. Vivências. 2019;16:77–97. doi: 10.31512/vivencias.v16i30.108. [DOI] [Google Scholar]
  8. Conselho Nacional do Meio Ambiente - CONAMA (2011) Resolução N° 430, de 13 de Maio de 2011. Brazil
  9. Cruz M, Jakobs-schoenwandt D, Isabel M, et al. Formulating bacterial endophyte: pre-conditioning of cells and the encapsulation in amidated pectin beads. Biotechnol Rep. 2020;26:e00463. doi: 10.1016/j.btre.2020.e00463. [DOI] [PMC free article] [PubMed] [Google Scholar]
  10. de Melo JRM, Tres MV, Steffens J, et al. Desolventizing organic solvent-soybean oil miscella using ultrafiltration ceramic membranes. J Memb Sci. 2015;475:357–366. doi: 10.1016/j.memsci.2014.10.029. [DOI] [Google Scholar]
  11. Ensano BMB, Borea L, Naddeo V, et al. Combination of electrochemical processes with membrane bioreactors for wastewater treatment and fouling control: a review. Front Environ Sci. 2016 doi: 10.3389/fenvs.2016.00057. [DOI] [Google Scholar]
  12. Ezugbe EO, Rathilal S. Membrane technologies in wastewater treatment: a review. Membranes (Basel) 2020;10(5):89. doi: 10.3390/membranes10050089. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. FAO . World food and agriculture - statistical pocketbook 2019. 2019. Rome: Organization of the United Nations (FAO); 2019. [Google Scholar]
  14. Gil-Pulido B, Tarpey E, Almeida EL, et al. Evaluation of dairy processing wastewater biotreatment in an IASBR system: aeration rate impacts on performance and microbial ecology. Biotechnol Rep. 2018;19:e00263. doi: 10.1016/j.btre.2018.e00263. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Grout L, Baker MG, French N, Hales S. A review of potential public health impacts associated with the global dairy sector. GeoHealth. 2020;4:1–46. doi: 10.1029/2019gh000213. [DOI] [PMC free article] [PubMed] [Google Scholar]
  16. Kurup GG, Adhikari B, Zisu B. Treatment performance and recovery of organic components from high pH dairy wastewater using low-cost inorganic ferric chloride precipitant. J Water Process Eng. 2019;32:100908. doi: 10.1016/j.jwpe.2019.100908. [DOI] [Google Scholar]
  17. Li X, Liu Y, Liu F, Liu A, Feng Q. Comparison of ferric chloride and aluminum sulfate on phosphorus removal and membrane fouling in MBR treating BAF effluent of municipal wastewater. J Water Reuse Desalin. 2017;7(4):442–448. doi: 10.2166/wrd.2016.151. [DOI] [Google Scholar]
  18. Mateus GAP, Formentini-Schmitt DM, Nishi L, et al. Coagulation/flocculation with Moringa oleifera and membrane filtration for dairy wastewater treatment. Water Air Soil Pollut. 2017;228(9):1–13. doi: 10.1007/s11270-017-3509-z. [DOI] [Google Scholar]
  19. Meiramkulova K, Devrishov D, Zhumagulov M, et al. Performance of an integrated membrane process with electrochemical pre-treatment on poultry slaughterhouse wastewater purification. Membranes (Basel) 2020;10:1–17. doi: 10.3390/membranes10100256. [DOI] [PMC free article] [PubMed] [Google Scholar]
  20. Nabbou N, Benyagoub E, Mellouk A, Benmoussa Y. Risk assessment for chemical pollution of dairy effluents from a milk processing plant located in Bechar (Southwest of Algeria) Appl Water Sci. 2020;10:1–12. doi: 10.1007/s13201-020-01309-w. [DOI] [Google Scholar]
  21. Prakash N, Garg A. Comparative performance evaluation of physicochemical treatment processes for simulated dairy wastewater. Int J Environ Sci Technol. 2016;13:2675–2688. doi: 10.1007/s13762-016-1099-8. [DOI] [Google Scholar]
  22. Precious Sibiya N, Rathilal S, Kweinor Tetteh E. Coagulation treatment of wastewater: kinetics and natural coagulant evaluation. Molecules. 2021;26:698. doi: 10.3390/molecules26030698. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. Rufus DP, Banu JR, Kannah RY, et al. Effect of dispersion treatment on dairy waste activated sludge to hasten the production of biogas. Front Energy Res. 2019;7:1–9. doi: 10.3389/fenrg.2019.00136. [DOI] [Google Scholar]
  24. Sarkar B, Chakrabarti PP, Vijaykumar A, Kale V. Wastewater treatment in dairy industries - possibility of reuse. Desalination. 2006;195:141–152. doi: 10.1016/j.desal.2005.11.015. [DOI] [Google Scholar]
  25. Turan M. Influence of filtration conditions on the performance of nanofiltration and reverse osmosis membranes in dairy wastewater treatment. Desalination. 2004;170:83–90. doi: 10.1016/j.desal.2004.02.094. [DOI] [Google Scholar]

Associated Data

This section collects any data citations, data availability statements, or supplementary materials included in this article.

Data Availability Statement

Not applicable.

Not applicable.

Articles from Journal of Food Science and Technology are provided here courtesy of Springer

RESOURCES