Executive Summary
Eldredge, Inc. is a major provider of by-product management services with the specific goal of performing these services in a responsible and environmentally conscious manner. With Eldredge’s multi-disciplined professional staff, field technicians and logistics specialists, Eldredge offers a complete spectrum of environmental services. Eldredge Inc. is headquartered in West Chester, PA and it provides services in the industrial, refinery, commercial, government, and utility markets. Eldredge, Inc. operates four main business units including:
1) Waste Transportation
2) Industrial Field Services
3) By-Product & Waste sourcing
4) Oil Reclamation & Water Treatment
Eldredge’s facility is permitted to handle an array of residual wastes, including waste oil, oily water, wastewater, groundwater, anti-freeze, oil filters, oily sludge, and oily solids. Each waste stream that is processed has its own unique process; however, waste streams do share resources with each other for processing. For the purpose of this analysis, we will be analyzing Eldredge’s bulk wastewater treatment portion of Eldredge’s processing and it will be assumed that there is a fully unit of labor at each resource group.
Process Description
In order to analyze fully the bulk treatment portion of Eldredge’s process, it will first be important to give a brief background on all of the processes, as there are many interconnections between processes. As Process flow diagram of the complete process can be found in Figure #1. Currently as part of Eldredge’s processing procedure material is either delivered to Eldredge in bulk (in tanker, roll-off) or in containerized (drums, totes) storage containers. Currently when a bulk delivery arrives at Eldredge, it is first split into two receiving categories:
1) Bulk Liquid
2) Bulk Sludge/Solids
The storage container is sampled by a plant employee and brought to the lab for a Quality Control test (QC) to ensure the material meets Eldredge’s processing capabilities. The complete sampling and QC process has about a 30-45 minutes throughput time for both a bulk liquid and a bulk sludge/solid. The QC process is a 6-step process consisting of seven separate testing stations including:
1) Total Halogens (TX)
2) PCB’s
3) PH
4) Flash Point
5) BS&W (Bottoms, Solids & Water)
6) Metals
7) Treatability
Each step in the process takes a set time to run, so multiple samples can be analyzed at the same time in different steps in the process. If demand requires, the lab can be running up the six samples at the same time. Once the sample has passed QC, the offloading technician is informed that they can now offload the material into Eldredge’s process. The offload time will take about 30-45 minutes depending of the type and quantity of material being offloaded.
All liquids that have passed the QC process will next be split into four separate processes flow:
1) Waste Oil
2) Oil/Water Mixtures
3) Wastewater
4) Glycols (aka - Anti-freeze)
Wastewaters that have passed the QC process will be either directly pumped into one of the 2 x 6,000-gallon wastewater processing tanks or into one of the 2 x 20,000-gallon storage tanks. The wastewater will be pumped into the storage tanks only if the process tanks are full and currently process wastewater. Once the wastewater is in the process tanks, chemicals are added in exact ratios to the wastewater to help separate solids and remove metals from the water. The type and amount of chemicals that are added were determined from the treatability testing that was performed in the QC process. Each treatment tank will take about 4 hours to process. The treated water from this process is pumped out of the tanks into the dissolved air floatation (DAF) tank, which is used to remove any remaining floatable material (like oil or other organic contamination). This DAF process will take about 30 minutes.
The treated water will continue through the process into the filter press, which are used remove additional solids and metals from the water. Water will pass through the filter press in about 30 minutes. After the filter press, the water is pumped through ion exchange resins columns as a polishing step to remove any remaining metals down to the parts per million level (if needed) so the water can meet the discharge permit limits. This water takes about 1 hour to pass through the exchange resins. This fully processed water is next sent to one of 3x 20,000 outbound storage tanks. This water is sampled and sent back to the lab again for a Final QC to ensure it meets Eldredge’s discharge limits. This QC process includes pH and metal testing, which takes about 15 minutes. Once the treated water has passed final QC, the water is either discharged locally to the local POTW or is loaded into a bulk tanker truck and transported to a regional POTW. Water discharged locally takes about 30 minutes and water sent to the regional POTW will take about 2.5 hours.
Waste oil that had passed the QC process is either pumped directly into one of the 4x 7,000-gallon oil processing tanks or into one of the 2 x 20,000-gallon storage tanks. The oil will be pumped into the storage tanks only if the process tanks are full. Once the oil is in the processing tanks, the oil is treated with chemicals and heat to separate any contaminates (water, solids, etc.) out of the oil. This process takes about 2.5 hours. Once the oil is processed, the good oil is pumped though a vibrating screen which takes about 30 minutes. This processed and filtered oil is then pumped into one of the 4 x 20,000 product oil storage tanks where it is held until is sold where it will be loaded on a 7,000-gallon tanker truck and transported to Eldredge’s customer sites. It can take anywhere from 2-3 hours to load a bulk tanker and transport the product oil to the customer.
Oil and water mixtures are pumped into one of the 2 x 20,000 storage tanks. The oil and water mixtures are allowed to sit in the tank for anywhere from 1 hour to 24 hours to allow the oil and water to separate. The oil portion is pumped into the oil process and the water portion is pumped into the water process. Glycols (Ethylene Glycol's and Antifreeze) that passed the QC process are loaded into 1 x 6,000-gallon separation tank. This glycol is stored in the separation tank for about 24 hours to separate out any water or oil. The separated glycol is transferred into a 1 x 6,000-gallon outbound storage tank. The water and oil separated is transferred into the oil and water process. The separated glycol is loaded onto a truck and transported offsite to a recycling facility who will reclaim the glycol into new antifreeze.
All solids/sludge (except debris) that have passed the QC will be offloaded into the stabilization pit. Any free liquids will be pumped from the pit and over into the liquid portion of the plant. Once all free liquids are removed, a proprietary blend of stabilization chemicals are added to the pit and mixed with an excavator bucket. This stabilization process is to solidify any free liquids in the sludge/solids and stabilize any containments that are in the material (including oil or metals). This process will take about 3 hours. Once this process is completed, the stabilized solids are removed from the stabilization pit, loaded into a bulk roll-off container, and transported to a landfill for disposal. This step of the process will take about 4 hours. Any debris that has been passed the QC process will be transferred into bulk roll-off container with false bottom and allowed to drain for at least 1 day. Once all liquids have drained, the oil and water is removed from the bottom of the roll-off container and pumped into the oil and water process. This roll-off container is then send off-site for energy recovery where the debris will be utilized for its BTU content and converted into energy.
Figure 1: Process Diagram
Current Status Analysis
Based on the current process, several possible failures in design and their consequences can be identified that need improvements. Each of the processes described is important to ensure that the operations Eldredge Inc. run smoothly. To analyze and measure the performance of processes, managers need to analyze several factors including efficiency, quality, costs, and flexibility. The most common metrics of process performance analysis include process capacity, utilization, flow time, cycle time, idle time, and process time among others. In this case, Eldredge’s process analysis will be based on these metrics with the aim of finding out whether they are efficient or some improvements are needed. For the purpose of this analysis, process will be defined as the steps take to convert input in to output. Cycle time is the time taken in the completion of successive units. Utilization can be defined as the time ratio when resources are being used to the time they are available for use as finished products.
Eldredge’s process time for a single unit wastewater is 6.5 hours and 8.5 hours of wastewater discharged to a local and regional POTW respectively. As such, it would be advisable for the company to discharge water locally to minimize process time. The process resources include quality control, offload, treatment tanks, DAF, filter press, ion exchange, final quality control, local and regional discharge. Final quality control has the highest capacity of 32 final QC per day while treatment tanks have the lowest capacity of four treatments a day. QC and offload have a capacity of 1.33 per hour while DAF, filter press, ion exchange and local discharge each have a capacity of two per hour. Finally, regional discharge has a capacity of 1.2 per hour. This indicates that while some process can save on time, the treatment tanks are slowing the speed making the process not to be efficient. The treatment tanks capacity of 0.5 treatments per hour or four treatments a day is the lowest and it presents a problem to the remaining processes, which have a higher capacity but have to be idle.
Consequently, the utilization of the final quality control process is the least with a percentage of 12.5. This is because it has a high capacity but will remain idle for a long time while discharged water goes through other processes. QC and offload each have a utilization of 37.50% while treatment tanks have 100% utilization. DAF, filter press, ion exchange and local discharge each have a utilization of 25% while regional discharge utilization is 41.67%. The utilizations indicate that there is room for improvements except in the treatment tanks, which have 100% utilization. The process capacity is being underutilized in final QC resource and the company needs to adjust its process to ensure that the resource capacity utilization increases.
Cycle time can be viewed as the time it would take for a process to repeat itself. The water processing has a cycle time of 0.25 per day. The cycle time is low because cycle time for each process is not balanced. Since the different process involve different activities, it is very difficult to have a balanced cycle time. It takes approximate 2 hours or 0.25 days with 8 hours per day to produce a unit of recycled water. The cycle time could be reduce if the management finds way to improve on capacity and utilization.
Recommendations
In order to help improve the bulk wastewater process at Eldredge, we have come up with three recommendations for the possible process improvement.
After careful evaluation of the liquid treatment portion of the process, one option is to fix the bottleneck. The bottleneck is the resource with the smallest capacity, which in this case is the treatment tanks. The process capacity is limited by this resource with a capacity of only 0.5 treatments per hour, the lowest of all resources. One option is to increase the number of treatment tanks. The next lowest capacity is regional discharge with a capacity of 1.2 discharges per hour. If we were to increase the number of treatment tanks to five, our capacity at the holding tanks would now change to 1.25 treatments per hour (10 treatments per 8-hour day). The cost associated with an increase of three treatment tanks would be $75,000. Legal fees and permitting fees would add another $45,000. This would raise the process capacity and change the utilization of the treatment tanks to 40% from 100%. This would also help in the event that one of the treatment tanks had a malfunction. Running at 100% utilization would mean that any problem with the resource (treatment tanks) would shut down the process down completely since there is no room for error with 100% utilization.
Alternatively, one could increase the number of holding tanks used prior to treatment. This would increase inventory and allow Eldredge to accept more containers or tankers of waste. The bottleneck here would still be at the treatment tanks but with the addition of a second shift, one could realize actual treatment of liquid waste in between shipments. This could help keep up with the demand from the holding tanks that would come from the increase inventory accepted. Overall, this could increase profits by increasing the number of accepted containers or tankers that are accepted but the additional cost of paying a second shift needs to be considered as well.
A third option would be to increase the number of exchange columns used in the 1-hour process of ion exchange. The capacity at this resource is two ion exchanges per hour. If we were to add two more columns, we could now increase our capacity to four ion exchanges per hour, which would cut our utilization in half to 12.5%. Certainly adding this resource which is downstream to the bottleneck is a possibility but unlikely to result in any meaningful change for the process.
A fourth option would be to increase the total numbers of hours per day. If we were to add another full 8 hour shift, the cost associated with that would be $XXX. By doubling the working hours, you can keep the bottleneck resource working. Though doing so will not technically reduce the cycle time, it will allow the bottleneck to produce when other operations are idle. The more time the bottleneck works, the more the total system produces.
Predicted Performance Improvements
Limitation & Implementation Issues
Conclusion
Process Flow Diagram
Bottleneck analysis
Lean operations
EOQ Model
Value Stream Mapping
Supply Chain Management
Inventory Build Up Diagram
