A project thesis submitted to the Civil Engineering Program Universiti Teknologi PETRONAS in partial fulfillment of the requirement for the. This final report has been prepared to report on the entire progress of the research into the anaerobic treatment of pharmaceutical wastewater. Mohamed Hasnain Isa, for all his guidance, cooperation, willingness to help and assist in the completion of the final year project.
The production of pharmaceutical products can be divided into three main phases: (I) research and development; (2) conversion of organic and natural substances into bulk pharmaceutical substances or compounds through fermentation, extraction and/or chemical synthesis; and (3) formulation and assembly of the final pharmaceutical product.
Treatment for pharmaceutical effluent
Anaerobic Wastewater Treatment
Three- Stages of Anaerobic Conversion of Organic Matter
Thus, the end products of fermentation (acetate, hydrogen and COz) are the precursors of methane formation (metagonesis). The free energy change associated with the conversion of propionate and butyrate to acetate and hydrogen requires that hydrogen be in low concentration in the system (H2<1 0-4 atm), or the reaction will not proceed (McCarty and Smith, 1986 ). Bacteria within anaerobic processes, called acetogens, are also able to use C02 to oxidize hydrogen and form acetic acids.
Methane production can occur using acetate, hydrogen and carbon dioxide, and methanol.
Types of Anaerobic Reactors
- Suspended growth process
- Attached growth process
- UASB (up-flow anaerobic sludge blanket) reactor
- Methane forming bacteria
The anaerobic contact process (Figure 2.7) overcomes the disadvantages of a complete mixing process by allowing sludge to be recycled. A medium is used to keep bacteria in the digester for relatively long periods and provide long solids retention time and short hydraulic retention time. In the up flow packed bed reactor or anaerobic filter (Figure 2.8), the packing is fixed and the wastewater flows up through the interstitial space between the packing and biogrowth (Metcalf & Eddy, 2004).
The UASB reactor is one of the most notable developments of anaerobic treatment processes introduced in the late 1970s in the Netherlands by Lettinga and his co-workers.
Methane-forming bacteria are strict anaerobes and are extremely sensitive to changes in alkalinity, pH and temperature. Therefore, the operating conditions in the digester must be periodically monitored and kept within optimal ranges. In addition to alkalinity, pH, and temperature, several other operating conditions should be monitored and maintained within optimal ranges for acceptable activity of methane-forming bacteria.
These conditions are gas composition, hydraulic retention time (HRT), oxidation reduction potential (ORP), and volatile acid concentration (Table 2.2) (Gerardi, 2003). The OLR equation was determined from the reactor liquid volume equation (Metcalf. & Eddy, 2004). Thus, with the known value of the liquid volume of the reactor, the OLR can be determined by substituting the following equation:
MATERIALS AND METHODS
Laboratory work performed includes chemical oxygen demand, total suspended solids, volatile suspended solids, ammonia nitrogen, pH, alkalinity and phosphorus testing for the influent and both effluents.
- Technical Details of Anaerobic Reactor (UASB)
The peristaltic pumps were calibrated in such a way that the flow rate of the incoming waste water could be controlled. The UASB reactors were seeded with sludge from the sludge thickener of the Wastewater Treatment Plant (STP) on the campus of the Universiti Teknologi PETRONAS (UTP). Monitoring and sampling of the influent and both effluent were performed routinely as shown in Table 2.
The pump will control the flow rate of the incoming raw wastewater entering both reactors. Because the reactor volume is 5 liters, the correlation between HRT and flow rate is shown in table 3.2.
Total Suspended Solids
In the laboratory works, after the work done for TSS, the VSS test served as the continuation of the work. During this period, the filtered organic material will be burned. The sample left in the foil will be called Fixed Solids and the sample that evaporated will be referred to as the Volatile Solids.
Chemical Oxygen Demand (COD)
The nitrogen is essential as a requirement for the nutrient requirements from the anaerobic digestion process. The method used according to the finding of the ammonia nitrogen was by adaptation of the Nessler method. The importance of the test was to monitor the nutrient requirements for the anaerobic digestion.
Adequate dilution should be performed prior to performing the test to avoid over-range readings. The procedure for performing the nitrogen in ammonia test involved mixing three solutions, namely mineral stabilizer, polyvinyl alcohol1 and Nessler's reagent (Figure 3.9).
Alkalinity and pH
- Phase 1
- Phase 2
- Phase 3
- Phase 4
- Phase 5
The percentage COD removal for the mesophilic reactor was in the range of 75%-90%, while for the thermophilic reactor the percentage COD removal was in the range of 60%-85%. During Phase Days, the influent COD increased to almost 2000 mg/L, the organic loading rate also increased due to the increase in influent COD. For the thermophilic reactor, the effluent concentration was quite high compared to the effluent from the mesophilic reactor, where the value ranged from 280 mg!L to 380 mg/L.
This caused disturbances in the smooth operation of the mesophilic reactor due to the temperature shock of the mesophilic microorganism. When restarting the reactor, the concentration of the mesophilic reactor effluent was higher compared to the thermophilic effluent. The COD concentration in the mesophilic reactor ranged from 800 mg/L to 1200 mg!L compared to the thermophilic reactor, which ranged from 300 mg/L to 330 mg!L.
The percent COD removal for mesophilic reactors was in the range of 65–70%, while the percent COD removal for the thermophilic reactor was 75–80%. Mesophilic offers a higher percentage of COD removal compared to thermophilic reactors from phase 1 to 3, but during phase 4 the thermophilic reactor performed better for COD removal as the mesophilic reactor did not operate efficiently due to temperature shock to microbes. The agitation processes must be performed to ensure that the wastewater is properly mixed to avoid fluctuations in the incoming COD result. During the phase change from phase 2 to phase 3, the result of COD in mesophilic reactor and thermophilic reactor was quite low from 100 mg/L to 200 mg/L (Appendix E), this happened due to the flushing of the residual wastewater from the previous phase .
The increase in Organic Loading Rate (OLR) ensured that both reactors operated efficiently at up to 90 percent removal (Figure 4.2). Referring to Figure 4.2 for overall performance, the increase in organic loading rate will cause the reactor to perform at a slightly lower efficiency because a shorter HRT causes a smaller COD removal compared to a longer HRT at the same influent concentration.
The result (Figure 4.3) had not shown any significant improvement for methane production even though COD removal increased to almost 1500 mg/L. The theoretical methane production was assumed to be more than 350 mL, compared to the actual data which was less than 300 mL (Figure 4.4). As noted in N.F Gray, 2004 p. 770, acetogenic and methanogenic bacteria are particularly sensitive to temperature, even a 2-3°C drop in mesophilic solvent will negatively affect biogas production.
There may be times when the temperature in the reactors increases more than the permissible range and it can be concluded as the inconsistency of the reactors to maintain the temperature. The leakage that can occur at the gas collection vessel and also at the pipe seems to be the main reason contributing to lower methane production. The pharmaceutical waste water itself may contain substances that can lead to low production of methane.
It can also be assumed that the methanogenic bacteria are not working due to lower alkalinity in the effluent (Figure 4.7).
The reason for this is not clear, but it may be related to temperature and pH instability. Ammonia nitrogen is essential for anaerobic digestion but can be inhibitory when present at concentrations >150 mg/L. The toxicity threshold for ammonia has been reported to be lOOmg/L as NH3-N (McCarty and McKinney, 1961).
Based on Figure 4.5, it can be concluded that the ammonia nitrogen concentration in the mesophilic reactor is higher than the concentration of ammonia in the thermophilic reactor and in the influent. During Phase 2, the concentration of phosphorus in mesophilic reactor effluent varied from 9-40 mg/L while for thermophilic reactor the total phosphorus concentration was in the range of II -38 mg/1. During Phase 3, the influent concentration is in the range of I 0-25 mg/L, while the concentration for the mesophilic and thermophilic effluent varies between 15-30 mg/L and 16-40 mg/L.
In Phase 4, the effluent from mesophilic reactor is high due to reactor instability and the concentration may be high due to sludge leaching. The concentration was in the range of 40-80 mg/L and 18-19 mg/L for mesophilic and thermophilic reactors. Based on Figure 4.5, phosphorus in the influent is high (>2 mg/L) and more than required.
However, the findings of the current study do not support previous research where the effluent concentration does not decrease rather than increase in the higher range than the influent. This is because bacteria have the ability to store excess phosphorus as polyphosphates in their cells.
Alkalinity and pH
Overall results showed that the pH value of thermophilic wastewater is higher compared to mesophilic wastewater (Figure 4.8).
LIST OF PARAMETERS FOR WHICH LIMITS SHOULD BE DETERMINED. iii) chloride (iv) cobalt (v) color. vi) Detergents, anionic (vii) Fluoride (as F) (viii) Molybdenum (ix) Nitrate Nitrogen (x) Phosphate (asP). Job Title Operation Total Phosphate Date I !1/1/zoos Ref. no. I FYP2/JSN002 Tide of person working Muhamad Farhan Clerk Observed w/o. 3 .1.2 Keep the distance between the Erlenmeyer flask and properly drop the polyvinyl alcohol into the Erlenmeyer flask.
Filling of sulfuric acids 2.1 Pouring the material into the body 2.U Put on the appropriate ppe (lab coat) inside the burette. Total suspended solids and date 2/16/2008 No. Ref FYP2/JSA/005 Volatile solids.