Assessment of LWR s Manure Treatment System with In-Sequence Solid Separation and Membrane Filtration of Liquid Hog Manure

Transcription

1 Assessment of LWR s Manure Treatment System with In-Sequence Solid Separation and Membrane Filtration of Liquid Hog Manure Final Report May 2011 September 2013 May 6, 2014 Prepared by: Carlie Pauls Environmental Compliance Specialist HyLife Ltd.

2 2 Table of Contents 1 Executive Summary 3 2 Objectives 3 3 Departures & Achievements 4 4 Production 8 5 Cost Analysis 8 6 Sample Analysis 9 7 Conclusion & Recommendations 14 8 Acknowledgements 15 Page List of Figures Figure 1: Proposed sequence of manure separation equipment 4 Figure 2: Installed sequence of manure separation equipment 4 Figure 3: Installed sequence of manure separation equipment with mechanical alterations 4 Figure 4: Sequence of manure separation equipment being utilized by the end of the trial 6 Figure 5: Proposed chemical treatment being applied to LWR s processes 6 Figure 6: Chemical treatment utilized by the end of the trial 6 Figure 7: LWR sample analysis pre sulphuric acid addition 13 Figure 8: LWR sample analysis post sulphuric acid addition 13 List of Tables Table 1: LWR Production Volume 7 Table 2: LWR Production Cost 8 Table 3: Raw Manure (lbs/1000 gal.) 9 Table 4: Solids (lbs/1000 gal.) 9 Table 5: LWR Patented Screen System (lbs/1000 gal.) 10 Table 6: Fine Solids Separator Effluent (lbs/1000 gal.) 10 Table 7: Membrane Separation System Reject (lbs/1000 gal.) 11 Table 8: Concentrate from Concentrator (lbs/1000 gal.) 11 Table 9: Membrane Separation System Clean Water (lbs/1000 gal.) 12

3 3 1.0 Executive Summary The incorporation of LWR (Livestock Water Recycling) technology on a modern hog operation was expected to separate hog manure into coarse and fine phosphorus rich solids, a nitrogen rich concentrate, and clean water. Following separation, these products would be independently land applied in compliance with the regulatory changes to the Manitoba Livestock Manure and Mortalities Management Regulation (LMMMR) which have been in effect since LWR technology was installed and operated at a HyLife hog operation in the RM of La Broquerie. The project has demonstrated that phosphorus removal greater than 95% can be achieved using LWR s proposed, patented, configuration of mechanical and chemical processes but at very high operational costs. End products were not manageable or concentrated to the expected extents. 2.0 Objectives This project was designed to utilize LWR technology and adapt this technology for commercial use on a modern hog operation. For this trial to be successful it was required to meet or exceed the following objectives: 1. Influent quantity: process a minimum of 13,500 imperial gallons of manure per day and operate for 365 days per year. This rate would be required in order to treat all of the manure produced annually by the hog operation. 2. Effluent quality: o 90-95% phos removal o Solids to consist of 30% dry matter o Final ammonium concentration to be 15X the influent concentration o Produce potable water for reuse in the barn 3. Labour: require a maximum of 2 hours operator labour per day 4. Cost: System to operate at a treatment cost of $0.01 per imperial gallon or less (not including cap. ex.) To achieve the above listed objectives, the following sequence of components was proposed along with flocculation and coagulation agents to treat sow manure from this farming operation: 1. Circulation tanks: used to achieve a uniform product which would allow for more consistent and reliable treatment 2. Screwpress: used to remove coarse solids 3. LWR patented screen system: used to remove solids 4. Fine solids separator: used to remove fine solids 5. Bag filters: water polishing to protect the membrane separation system 6. Membrane separation system: used to concentrate the ammonium and produce clean potable water for reuse in the barn

4 4 7. Granular Activated Carbon (GAC): used to produce clean potable water for reuse in the barn 8. Vacuum distillation concentrator (optional): used to further concentrate ammonium 3.0 Departures & Achievements The sequence of components listed in Section 2 was modified prior to being installed. The installed sequence of mechanical components is demonstrated in Figure 2 below. Following the installation, the sequence of mechanical processes was altered in order to produce quality effluent products specified in Section 2. HyLife was obligated to accept operational and configuration changes proposed by LWR. The resulting sequence of components is shown in Figure 3. Many of the objectives could not be met using the originally proposed sequence of components and the system required ongoing modifications in order to achieve even limited success. A primary component that required numerous alterations was the solids removal step where the moisture content of the solids was too high to allow for any piling or economical transportation of the solids via the originally proposed sequence of mechanical and chemical separation. Methods that were proposed and trialed for dewatering the solids include: LWR patented screen system only LWR patented screen system followed by geotextile for additional passive dewatering LWR patented screen system followed by micro ingredient bags for additional passive dewatering Coarse screen installed previous to the LWR patented screen system removed larger particles

5 5 and protected pumps and other equipment within the treatment process LWR patented screen system followed by transfer tank with pump temporarily installed to transport the solids to the lagoon for storage. Solids at this time were less than 15% DM and were easily pumped to the lagoon Chemical flocculation chamber pre LWR patented screen system improved the operating cost by optimizing chemical usage, however it did not improve solids dewatering as expected Refurbished screwpress post LWR patented screen system showed promise but did not perform as expected. The screwpress had the ability to dewater the solids but fines were forced through the slotted screen on the screwpress with the liquid portion of the manure which increased phos levels in the liquid fraction of the manure. Other modifications were hypothesized to achieve the originally stated objectives, including the following: Removing butterfly valves and replacing 90 elbows with flex hose wherever possible. This reduced the occurrence of plugging in the 2 raw manure lines leading from the circulation tanks to the LWR patented screen system therefore reducing downtime and increasing production time. The installation of the polyblend unit to reduce operator labour by 30 minutes therefore allowing more time for optimizing production. The installation of a bulk chemical storage tank decreased chemical costs which contributed to an improved cost per gallon. The extension of the conveyor belt increased the volume of the solids storage to allow for more continuous operations. Inclusion of a weekend shift in 2012 reduced settling of manure in the circulation tanks which decreased maintenance time and increased operating time. In 2013, operating with a weekend shift was not an option since the complexity of the chemistry required having a qualified LWR technician onsite for daily operations. This technician was not available full time. Installation of a surge tank provided consistent water flow to the polyblend unit for more reliable chemical feed therefore assisting in the optimization of the chemistry. The installation of a heater increased operating time in winter and alleviated issues caused by freezing of infrastructure during the winter months. Adjustments to the operating procedures were necessary to reflect new system components and modified chemistry as the project progressed. Elimination of the concentrator component was proposed by the LWR manufacturer after the concentrator blower was damaged by the membrane separation system reject water which impacted the bearings therefore causing the lobes of the blower to seize together. It was proposed that by making further modifications to the chemistry, the LWR system could achieve the desired ammonium concentration in the membrane separation system reject without the

6 6 use of the concentrator. Figure 4 demonstrates the sequence of mechanical components that were being utilized at the time that the trial was terminated. The chemicals being utilized in the treatment process were modified as per the LWR manufacturers recommendation. These changes were proposed to increase the quality of the effluent products. Some of the chemical alterations required a more qualified operator which the LWR manufacturer also provided for onsite operations. Chemical injection points were relocated in an attempt to maximize chemical efficiency and decrease chemical usage which in turn would decrease the cost per gallon. Chemical modifications were ongoing throughout the trial as per the manufacturers recommendation. The chemical sequence originally proposed to aid in the treatment process is demonstrated in Figure 5. The LWR manufacturer made alterations to the chemical processes by adding hydrochloric acid and sulphuric acid. The addition of these two acids required having a qualified LWR technician and occasionally the LWR manufacturers trained engineer onsite for the remainder of the trial. The chemical treatment process being utilized by the end of the trial is demonstrated in Figure 6 below.

7 7 There were several outstanding challenges that prevented the LWR system from performing as per the design specifications. The following challenges could not be resolved over the three year trial due to infrastructure limitations, and contract obligations with the LWR manufacturer: Circulation tanks: these tanks were provided by the LWR manufacturer. The shape of these tanks encouraged settling of minerals and grit along the sloped sides of the tank. After a substantial amount of settling had occurred, the heavy mineral material would slide to the bottom of the cone plugging the 4 lines beneath the cone. The circulation pump was not capable of moving this heavy material. The circulation tanks were ineffective at creating a homogenous manure product. The variability of the manure caused by these tanks required having an operator onsite all day to make chemical adjustments to accommodate the varying influent characteristics. LWR patented screen system: the self-washing cycle of the LWR patented screen system added significant volumes of water to the solids. The water could not be turned off since it was required for proper screen functions. O & M: the LWR system had high onsite operational and maintenance requirements. Chemical usage: consumption was higher than anticipated, constantly changing with ever increasing complexity. This required having specially trained staff onsite to manage chemical dosing appropriately. Production time decreased as a result since the LWR technician had only limited availability. Concentrator: not effectively commissioned and ammonium concentrations as per the design spec were not realized using the concentrator. H₂S: concentrations of H₂S inside the building during the winter months could not be avoided. In the summer months all doors could be opened to reduce H₂S concentrations. Additional ventilation was added to the system to accommodate these issues, but due to operational complexity, use of the fume hood was limited due to the constant access required to the LWR patented screen system. 4.0 Production The livestock facility where the LWR system was located produces 13,500 imperial gallons of waste per day or approximately 5 million gallons per year. The LWR treatment system was designed specifically for this livestock facility and was proposed to treat all of the manure produced annually by the livestock facility. The chart below summarizes the volume of manure treated annually by the LWR system over the past three years of the trial. Table 1: LWR Production Volume.

8 8 The highest volume of production occurred during the summer months, while very little production occurred during the winter months. Reasons why production peaked in the summer and fell short during the winter are explained in Section 3. Ongoing repair and maintenance activities as well as continuous changes in chemistry decreased production since the complexity of the chemistry required having a qualified LWR technician onsite to operate the system for the remainder of the trial. The maximum volume of manure that the system treated in any given year was less than 10% of what was proposed by the LWR manufacturer. Production volumes fell consistently short of design specifications due primarily to repair and maintenance and changes to the process configuration and chemistry. As a result of striving to meet the quality objectives, the system was unable to achieve the specified quantity. 5.0 Cost Analysis The design specified at operating cost of $0.01. WThe LWR system showed an improvement in the cost per gallon in 2012 as a result of system modifications and improvements in These alterations included receiving chemicals in bulk as well as infrastructure changes aimed at reducing operator labour. In 2013, there was a reduction in the annual costs due to the exclusion of the concentrator component and all costs associated with that component. In 2013 it should be noted that we experienced a lower volume of production and higher labour inputs which translates to a higher cost per gallon than in previous years. Table 2: LWR Production Cost. Based on current manure application costs, the implementation of the LWR system was not proven as a feasible solution in this circumstance. Current manure application costs for this site are under $0.01 per gallon, or $0.64 per weaned pig. With recent implementation of the phos ammendment of the MLMMMR in southeastern Manitoba, application costs are anticipated to increase on affected facilities. The manure application costs for this site, as a result of hauling a portion of the manure, are anticipated to be $0.014 per gallon or $0.90 per weaned pig in 2014, and $0.02 per gallon or $1.28 per weaned pig in 2015.

9 9 6.0 Sample Analysis Samples were collected at various stages of the LWR treatment process. Table 3 raw manure analysis provides a benchmark for comparison as we progress through the different stages of the LWR treatment process. Table 3: Raw Manure (lbs/1000 gal.) It is important to note that sample set was collected at a time when fine solids material was recirculated from the bottom of the fine solids separator back to the circulation tanks to be reprocessed, hence the reason we see an elevated phosphorus value in this particular sample. It should also be noted that sample set was collected at a time when the membrane separation system reject was being re-circulated back to the circulation tanks which increased the concentration of salts and diluted the concentration of phosphorus. The solids produced by the LWR system would be classified as semi-solid manure and could easily be pumped from inside the treatment building to the manure storage facility. Table 4: Solids (lbs/1000 gal.)

10 10 In Table 4, we observe that the % dry matter improved over time as a result of the introduction of the screwpress. Phosphorus has also become increasingly concentrated due to the optimization of the chemistry. The solids produced did not meet the quality objectives previously described in Section 2 of this report. Sampling the LWR patented screen system effluent was conducted in house since immediate test results were necessary to make appropriate changes to the chemistry in a timely manner. As an example, the % dry matter from sample set would indicate that alterations to the chemical dosage were required to improve solid-liquid separation. Table 5: LWR Patented Screen System Effluent (lbs/1000 gal.) Up to 98% of the phosphorus had been removed via mechanical and chemical separation prior to the fine solids separator stage. It is important to note, as previously stated in Section 4, that the system was incapable of treating more than 10% of the manure produced by this livestock facility. In Table 5, the sample demonstrated a significant increase in sulphur content. This is a result of the use of sulphuric acid in the treatment process. Fine solids separator effluent samples also showed high levels of sulphur in earlier testing witnessed in the sample from Table 6. The sulphur levels were elevated at this stage due to relocation of the sulphuric acid injection point in relation to the sample port. Table 6: Fine Solids Separator Effluent (lbs/1000 gal.)

11 11 Membrane separation system influent ph was adjusted to be near a ph of 4 which would theoretically assist in the stabilization of ammonium. The ph was adjusted using sulphuric and hydrochloric acid. This method of ammonium stabilization showed promise, however the benefits were not realized during this trial. The highest levels of ammonium concentration that were achieved are listed in the membrane separation system reject data found in Table 7. Table 7: Membrane Separation System Reject (lbs/1000 gal.) The ammonium concentrations that were achieved using the LWR treatment system did not meet the objectives for ammonium concentration previously listed in the quality objectives of Section 2. Another method that was tested for producing an ammonium concentrated product was the vacuum distillation unit or Concentrator. The concentrator unit installed at this facility was never effectively commissioned. Sample results are indicated in Table 8. Table 8: Concentrate from Concentrator (lbs/1000 gal.) The final stage of the LWR system was the production of clean potable water, adequate for reuse in the barn. The clean water produced by the membrane filtration system was not of potable quality as indicated by the sample results found in Table 9. For samples to be of potable quality the total coliform count must be below 10 and the fecal coliform count must be zero.

12 12 Table 9: Membrane Separation System Clean Water (lbs/1000 gal.) Periods of non-operation resulted in stagnant water within the membrane separation system infrastructure. This contributed to the growth of coliforms. During consistent operations, the coliform counts were lower, but did not meet or exceed drinking water requirements. In Table 9, the sample showed that no coliform were present. It should also be noted that the membrane separation system required constant manual cleaning using fresh water and sulphuric acid. Figure 7 and Figure 8 demonstrate the average concentrations by stage for the data collected before and after the introduction of sulphuric acid in the LWR treatment process. The inclusion of sulphuric acid was proposed to improve the ammonium concentration in the membrane separation system reject and was added based on the manufacturers recommendation.

13 13 Figure 7: LWR Sample Analysis Pre Sulphuric Acid Addition (lbs/1000 gal.) Figure 8: LWR Sample Analysis Post Sulphuric Acid Addition (lbs/1000 gal.)

14 Conclusion & Recommendations The LWR trial at this facility was unsuccessful in fulfilling the original objectives using LWR s manure treatment technology. 1. Influent quantity: The system was not commercially viable at the time of install. Ongoing process changes were required and limited the time available for production. The LWR treatment system processed only 10% of the manure volume that it was designed to process. 2. Effluent quality: o Phosphorus removal greater than 95% was achieved using LWR 4 polymer solution, Aluminum Sulphate and mechanical means, primarily the LWR patented screen system. o The maximum dry matter content of the solids was 15.37%. At this moisture %, manure is considered a semi-solid and as such it could not be handled using conventional manure application equipment and did not meet the design specifications. o Ammonium concentrations were significantly lower than anticipated and HyLife did not experience a cost/benefit by producing the ammonium concentrate using this portion of the treatment technology. o Clean water was not of potable quality and could not be reused within the facility. 3. Labour: Operating the LWR system required an average of four times more labour than anticipated due to high maintenance requirements and ongoing operational challenges. 4. Cost: The cost per gallon improved as a result of purchasing chemical in bulk. However, operating cost remained high in subsequent years due to unanticipated labour and maintenance requirements and a low production volume. Cost per gallon was $ $0.38. Performing this trial has allowed HyLife to address challenges that are specific to this particular manure treatment technology as well as challenges that are typical of manure treatement technologies in general. While this manure treatment system did not prove itself to be economically feasible, the trial was beneficial due to an improved knowledge base related to manure treatment facility design/configuration, chemical dosing, and manure characteristics. HyLife is committed to continued research of alternative manure treatment technologies while applying the knowledge that has been gained from performing this trial. The knowledge base that has been developed as a result of this trial will ensure that HyLife is successful in meeting its primary objectives in future trials involving the solid-liquid separation of manure. A successful trial in the near future will benefit Manitoba s pork industry while maintaining compliance with the Manitoba Livestock Manure and Mortalities Management Regulation.

15 Acknowledgements HyLife would like to thank Livestock Water Recycling (LWR), Prairie Agricultural Machinery Institute (PAMI) and Manitoba Agriculture, Food and Rural Development for their contribution and continued support of this trial. This project was funded in part by the Manitoba Livestock Manure Management Initiative (MLMMI), the Manitoba Pork Council and MRAC. MLMMI is funded by the Canada and Manitoba governments through Growing Forward 2, a federal-provincial-territorial initiative. Disclaimer Any data, analyses of data, project results and conclusions conveyed in this report are those of the project researcher and not of the government of Canada or Manitoba.