DOF/DAF comparison for the treatment of milk industry wastewater

Santos Pereira, Magno dos; Borges, Alisson Carraro; Muniz, Gustavo Lopes; Heleno, Fernanda Fernandes; Faroni, Lêda Rita D'Antonino

doi:10.4136/ambi-agua.2553

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ARTICLES • Rev. Ambient. Água 15 (5) • 2020 • https://doi.org/10.4136/ambi-agua.2553 copy

DOF/DAF comparison for the treatment of milk industry wastewater

Comparação entre FAD e FAOD para o tratamento da água residuária de laticínios

Authorship SCIMAGO INSTITUTIONS RANKINGS

Abstract

The objective of this study was to evaluate the efficiency of dissolved ozone flotation (DOF) in comparison to dissolved air flotation (DAF) for treatment of milk industry wastewater (MW). In the first phase of the experiment, a synthetic milk wastewater (SMW) was used to evaluate DOF and DAF, with and without addition of hydrogen peroxide, at pH 4.0 and pH 11.4. In the DOF tests, the concentration of ozone was equal to 19 (± 0.5) mg L^-1 and in the tests with addition of hydrogen peroxide, the H₂O₂/O₃ ratios tested were 0.5, 1.0 and 1.5. In the second phase, tests were performed using three MW from three different industries to validate the results obtained and to determine the DOF system's ability to treat this type of effluent. The parameters tested during validation were turbidity, total suspended solids, oils and greases (O&G), chemical oxygen demand (COD), biochemical oxygen demand (BOD), total nitrogen (TN) and total phosphorus (TP). It was observed that the efficiency of the treatments was better at pH 4.0. The results showed a reduction of the efficiency with the use of DOF. The addition of H₂O₂ in DAF and DOF also resulted in reduced system efficiency. The results obtained with SMW only approximated those obtained with the MW from one of the industries that contained the largest traces of milk and cheese.

Keywords:
advanced oxidation process; dairy wastewater; dissolved ozone flotation

Instituto de Pesquisas Ambientais em Bacias Hidrográficas Instituto de Pesquisas Ambientais em Bacias Hidrográficas (IPABHi), Estrada Mun. Dr. José Luis Cembranelli, 5000, Taubaté, SP, Brasil, CEP 12081-010 - Taubaté - SP - Brazil
E-mail: ambi.agua@gmail.com

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[1] ^*Corresponding author: Alisson Carraro Borges, e-mail: borges@ufv.br

Stages of the experiment	Description
1	Dissolved air flotation tests
2	Dissolved ozone flotation tests
3	Dissolved air flotation tests with addition of H₂O₂
4	Dissolved ozone flotation tests with addition of H₂O₂

pH	Parameters	DAF				DOF
pH	Parameters	Mean	SD	CV	Efficiency	Mean	SD	CV	Efficiency
4	Turbidity	96.7	2.7	2.8	84.5 (a)	141.6	3.2	2.2	77.3 (b)
	Delta color	2.4	0.04	1.7	83.1 (a)	2.9	0.2	6.0	79.8 (b)
	COD	385.5	25.6	6.6	87.5 (a)	246.4	5.7	2.3	92.0 (b)
	TOC	641.1	7.2	1.1	53.8 (a)	650.0	5.9	0.9	53.2 (a)
11.4	Turbidity	1192.0	22.8	1.9	-90.7 (a)	1361.6	12.1	0.9	-119.6 (b)
	Delta color	18.2	0.3	1.6	-27.9 (a)	18.8	0.3	1.6	-32.1 (a)
	COD	2571.0	23.8	0.9	17.9 (a)	2632.0	22.9	0.9	15.9 (a)
	TOC	940.1	87.9	9.4	29.4 (a)	908.2	61.4	6.8	31.8 (a)

pH	H₂O₂/O₃ ratio		Parameters
pH	H₂O₂/O₃ ratio		Turbidity	Delta color	COD	TOC
4.0	0.5	Mean	151.2	4.7	547.54	595.27
		SD	1.2	0.23	42.3	27.65
		CV (%)	0.79	4.97	7.73	4.64
		Efficiency (%)	75.8 (a)	66.8 (a)	82.0 (a)	49.3 (a)
	1.0	Mean	285.6	6.63	676.18	602.74
		SD	2.4	0.52	17.85	29.38
		CV (%)	0.84	7.81	2.64	4.87
		Efficiency (%)	54.3 (b)	53.3 (b)	77.7 (b)	48.8 (a)
	1.5	Mean	419.2	7.17	856.27	655.85
		SD	43.34	1.43	35.7	44.56
		CV (%)	10.34	19.93	4.17	6.79
		Efficiency (%)	32.9 (c)	49.5 (b)	71.8 (c)	45.0 (a)
11.4	0.5	Mean	1101.6	18.31	2777.3	1025.8
		SD	4.8	0.27	81.51	74.76
		CV (%)	0.44	1.48	2.93	7.29
		Efficiency (%)	-76.3 (a)	-28.9 (a)	8.1 (a)	19.3 (a)
	1.0	Mean	983.20	17.70	2688.7	1174.9
		SD	4.74	14.62	43.96	35.99
		CV (%)	0.48	82.56	1.64	3.06
		Efficiency (%)	-57.3 (b)	-24.7 (a)	10.98 (a)	7.60 (a)
	1.5	Mean	873.60	18.20	2205.6	1012.4
		SD	25.29	0.38	17.15	44.11
		CV (%)	2.89	2.11	0.78	4.36
		Efficiency (%)	-39.8 (c)	-28.2 (a)	27.0 (b)	20.4 (a)

Parameters	Sample 1	Sample 2	Sample 3
Turbidity (mg L^-1)	3500.0 (±53.1)	602.0 (±26.0)	498.0 (±3.4)
TSS (mg L^-1)	2580.0 (±176.6)	580.0 (±22.7)	480.0 (±13.0)
pH	7.52	12.55	6.03
Delta color	14.5 (±0.7)	11.2 (±0.6)	10.5 (±0.4)
COD (mg L^-1)	8876.4 (±187.7)	3938.0 (±16.4)	7653.8 (±27.0)
BOD (mg L^-1)	6810.0 (±64.3)	2688.0 (±5.0)	4590.0 (±17.2)
COD/BOD	1.3	1.46	1.67
O&G (mg L^-1)	4296.7 (±62.6)	101.0 (±1.6)	1201.0 (±20.6)
TN (mg L^-1)	64.4 (±4.3)	92.4 (±1.7)	154.0 (±1.3)
TP (mg L^-1)	30.4 (±0.4)	43.0 (±0.1)	56.6 (±0.1)

Sample	Parameters	DAF				DOF
Sample	Parameters	Mean	SD	CV	Efficiency	Mean	SD	CV	Efficiency
1	Turbidity (mg L^-1)	117.6	4.3	3.7	96.6 (a)	167.6	9.1	5.4	95.2 (b)
	Delta Color	3.2	0.4	11.0	77.8 (a)	4.0	0.3	6.7	72.7 (a)
	COD (mg L^-1)	2233.8	95.2	4.3	74.8 (a)	2267.1	79.6	3.5	74.5 (a)
	BOD (mg L^-1)	960.0	18.3	1.9	85.9 (a)	982.1	26.8	2.7	85.6 (a)
	O&G (mg L^-1)	218.0	12.0	5.5	94.9 (a)	607.2	20.8	3.4	85.9 (b)
	TSS (mg L^-1)	190.4	26.6	13.9	92.6 (a)	197.3	14.1	7.1	92.4 (a)
	TN (mg L^-1)	14.3	1.9	13.3	77.7 (a)	14.6	1.9	13.3	77.4 (a)
	TP (mg L^-1)	18.5	0.5	2.7	39.2 (a)	20.5	0.3	1.2	32.6 (b)
2	Turbidity (mg L^-1)	113.9	12.1	10.7	81.1 (a)	166.8	5.5	3.3	72.3 (b)
	Delta Color	5.9	0.7	11.8	47.4 (a)	6.6	0.2	2.6	40.7 (a)
	COD (mg L^-1)	2576.8	21.8	0.8	34.6 (a)	2657.8	21.8	0.8	32.5 (b)
	BOD (mg L^-1)	1936.8	7.2	0.4	27.9 (a)	1944.0	7.2	0.4	27.7 (a)
	O&G (mg L^-1)	0.0	0.0	0.0	100.0 (a)	0.0	0.0	0.0	100.0 (a)
	TSS (mg L^-1)	80.8	7.3	9.1	86.1 (a)	106.4	3.7	3.4	81.7 (b)
	TN (mg L^-1)	43.9	1.6	3.7	52.5 (a)	42.9	1.6	3.8	53.5 (a)
	TP (mg L^-1)	42.5	0.2	0.4	1.2 (a)	42.7	0.1	0.3	0.7 (b)
3	Turbidity (mg L^-1)	305.6	4.2	1.4	38.6 (a)	310.8	2.4	0.8	37.6 (a)
	Delta Color	11.2	1.0	9.0	-6.4 (a)	12.6	0.4	3.2	-20.5 (a)
	COD (mg L^-1)	5015.4	34.3	0.7	34.5 (a)	4721.9	40.2	0.9	38.3 (b)
	BOD (mg L^-1)	2612.0	18.3	0.7	43.1 (a)	2280.0	52.3	2.3	50.3 (b)
	O&G (mg L^-1)	232.0	8.5	3.7	80.7 (a)	263.6	17.0	6.5	78.1 (a)
	TSS (mg L^-1)	273.8	14.9	5.5	43.0 (a)	279.2	8.0	2.9	41.8 (a)
	TN (mg L^-1)	118.7	1.9	1.6	22.9 (a)	119.8	1.9	1.6	22.2 (a)
	TP (mg L^-1)	42.5	0.2	0.4	24.9 (a)	42.2	0.3	0.6	25.3 (a)