Statistical Modeling to Forecast Odor Levels of Biosolids Applied to Reuse Sites

Real-Time Monitoring and Forecasting of Odor After Dewatering in Wastewater Treatment

“…DCWASA tries to maintain the retention time of secondary sludge in the blankets no shorter than two hours, and no longer than one day (Peot 2006). The height of the sludge blanket depth depends on flow and detention time.…”

“…Additionally, the study by Sekyiamah (2005) suggested that concentration of reduced sulfur at the bottom of secondary settling tank strongly correlates with the sludge blanket level or the higher the sludge blanket level the greater reduced sulfur produced. In another recent study, Gabriel, et al (2006) showed that the blanket depth from the day before have the greatest change on the biosolids odor level. But, the correlation of the secondary east blanket is 0.039 which represents virtually no correlation with total reduced sulfur, however only the secondary west odd blanket has a positive correlation with total reduced sulfur.…”

“…For this reason, even though we can find the process variables that have strong correlation with total volatile reduced sulfur, we have to check the correlation among those variables, and some of them may not be used in the regression model which can be seen in Section 4.2. According to Peot (2006), the maximum of retention time of process variables from upstream process through the dewatering process will be one day. Therefore, the previous data (D-1) of process variables except polymer addition at dewatering will be used with real time monitoring data in correlation analysis.…”

“…In the last few years, DCWASA has researched statistical odor forecasting models to predict the odor levels based on ambient conditions. Gabriel, et al (2005) identified dimethyl disulfide levels from biosolids by using statistical modeling, and Gabriel, et al (2006) using statistical modeling to forecast odor levels of biosolids applied to reuse sites. The present research excludes that work by comparing odors with process data before biosolids are delivered to the field.…”

“…At DCWASA, several studies are underway to minimize odors. These include investigating the amount of odor released when different amounts of lime are incorporated into samples (Murthy 2002a), forecasting odor levels for biosolids product based on ambient conditions (Vilalai 2003), prediction of dimethyl disulfide levels from biosolids using statistical modeling (Gabriel, et al 2005), statistical modeling to forecast odor levels of biosolids applied to reuse site (Gabriel, et al 2006), and an evaluation of methods for qualifying lime incorporation into mechanically dewatered sludge (North 2003). In addition, other studies have investigated the potential for odor release when a sludge sample is contained in the Teflon tube opened for 30 minutes, 24 hours, and seven days.…”