Intermittent Ozone Application in Aerobic Sludge Digestion

Figures & data

TABLE 1.   Characteristics of WWTPs Sampled Within the Scope of this Study

Characteristics	Tatlar Wastewater Treatment Plant	Kayseri Wastewater Treatment Plant	Konacık Wastewater Treatment Plant	METU VRM Wastewater Treatment Plant
Type	Conventional activated sludge plant	Biological Nutrient Removal (BNR)	Static membrane plant	Vacuum rotating membrane plant
SRT (days)	2–4	20–25	40–50	10
Sustainable flow handled m^3 day^−1	971.000	110.000	1200	200
Sample points	RAS	Aeration tank	RAS	Aeration tank

FIGURE 1. The soluble COD values for 2, 3, 4 and 6 min ozonation in comparison with a control group not having ozone treatment.

FIGURE 2. The MLSS values for 2, 3, 4 and 6 min ozonation in comparison with the control group.

TABLE 2.   Oxygen Uptake Rates for 4- and 6-Min Ozonated Samples and Control Groups According to Days

OUR(dO/dt)	Control (mg L^−1h^−1)	4 min (mg L^−1h^−1)	6 min (mg L^−1h^−1)
First day	−2.88	−2.88	−2.88
Second day	−2.16	−2.88	−1.08
Third day	−1.8	−1.08	−0.072
Fourth day	−1.44	−0.72	−0.18
All flasks contained 2.3 g L^−1 MLSS.

TABLE 3 .  Results of the Second Set of Experiments with Ozone Doses Applied to Treatment Plant Sludges and Their Comparison with the Literature Data

WWTP	Ozone dose applied, kg O3 kg^−1 MLSS removed	Ozone dose applied, kg O3 kg^−1 initial MLSS	(%) MLSS reduction (initial MLSS - final MLSS g L^−1)	(%) MLVSS reduction (initial MLVSS - final MLVSS g L^−1)
WWTP 1	0.00130	0.00117	85.9%	87.5%
			(3.33-0.47)	(2.73-0.34)
WWTP 2	0.00146	0.00121	82%	95%
			(3.08-0.53)	(2.12-0.1)
WWTP 3	0.00105	0.000803	77%	77%
			(4.63-1.08)	(3.07-0.68)
WWTP 4	0.00165	0.00120	72.6%	90.7%
			(3.1-0.85)	(2.25-0.21)
Yasui et al. (1996) *	0.165	−	−	−
Sakai et al. (1997) *	0.133-0.178	−	−	−
Kobayashi et al. (2001) *	0.250	−	−	−
Sievers et al. (2004) *	0.395	−	−	−
*^Ozone applications were on the recycle lines.

FIGURE 3. The soluble COD values for WWTP1, WWTP2, WWTP3 and WWTP4 during 4 days of experimentation.

FIGURE 4. Total phosphorus and ortho-phosphate-P values for WWTP4; (1) and (2) represent the two parallels.

FIGURE 5. Total phosphorus and ortho-phosphate-P values for WWTP1; (1) and (2) represent the two parallels.

FIGURE 6. The MLSS destruction when initial sludge concentration was 7.68 g MLSS/L at 4’ + 4’ + 4’+ 6’ ozonation pattern.

FIGURE 7. The MLVSS destruction when initial sludge concentration was 5.9 g MLVSS/L at 4’ + 4’ + 4’ + 6’ ozonation pattern.

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