The Application of Response Surface Methodology in the Study of Photodegraded Industrial Dairy Effluents by the Photo-Fenton Process: Optimization and Economic Viability

Table 3

Results of physical/chemical analyses in natura and posttreatment dairy effluents.

Parameters	Results		Data in the literature	References	Release standards* (mg L^−1)
	In Natura	After AOPs and precipitation
Aspect	Turbid	Clear	—	—	—
True color (Co Pt)	431.9	27.86	—	—	Absent
Turbidity (NTU)	1033	12.00	—	—	Absent
pH	6.0–6.4	8.0–8.50	5.25–8.0	[17, 19–21]	5–9
Odor	Pungent	Absent	—	—	—
COD (mg L^−1 O2)	9000–10000	929.0–935.0	797–8000	[19–21]	—
BOD (mg L^−1 O2)	2300–2500	508.5–515.8	1292–60000	[20]	60
BOD/COD	0.25	0.65	—	—	—
DOC (mg L^−1)	1513–1800	336.2–356.1	2500–5000	[5, 20]	—
Phosphorus (mg L^−1)	108.7	3.0	38.6–227.1	[17, 20]	—
NH3-N (mg L^−1)	158.0	0.0027	0.25–57	[19]	20
Organic N (mg L^−1)	179.9	0.0047	16.5–1048	[19, 20]	—
^aST (mg L^−1)	5680	2830.60	545–15720	—	—
^bSTF (mg L^−1)	986	880	119		—
^cSTV (mg L^−1)	4800	1746.0	426–10900	[19]	—
Phenol (mg L^−1)	>0.005	>0.005		—	0.5
Oil and grease (mg L^−1)	2002.5	0.000	4680	[22]	50
Chloride (mg L^−1)	1301.75	27.0	—	—	—
Cyanide (mg L^−1)	Absent	Absent		—	0.2
Copper (mg L^−1)	1.39	7.8		—	1.0
Chromium (mg L^−1)	Absent	Absent		—	0.1
Cadmium (mg L^−1)	0.246	0.254		—	0.2
Iron (mg L^−1)	48.48	0.013	—	—	15.0
Lead (mg L^−1)	0.031	0.028		—	0.5
Zinc (mg L^−1)	5.00	5.00		—	5.0
Manganese (mg L^−1)	3.120	2.940		—	1.0
Nickel (mg L^−1)	0.39	0.32		—	2.0

aST: total solids, ^bSTV: fixed solids, and ^cSTV: total volatile solids.
*Standards for effluent release in water bodies (Article 18 CETESB CONAMA 357/05). (—): not specified.