1991 Food Industry Environmental Conference

J J Controlling Nitrogen Loading for

Land Application of Poultry Processing Wastewater

Robert L. Kendall, CPSS President

Kendall & Associates Marietta, Georgia

ABSTRACT

Land application has been used for many poultry processing industry as an effective treatment/disposal of wastewater. The size

years by the method for final and cost of most

land application systems in the industry are dictated by nitrogen loading. is the most widely used method for controlling the cost of wastewater treatment. The risk in taking this approach, however, is that contamination of ground water with nitrate-nitrogen may result.

This paper presents a case history of the efforts made by Mott's Prepared Foods at its plant in Talmo, Georgia to manage the nitrogen loading to its land application system ( L A S ) . The on-going efforts, which continue up to the present, have been necessitated by elevated nitrate levels that were detected in ground water monitoring wells shortly after the system went into operation. The various measures taken by Mott's fall into three general categories: 1) upgrading the wastewater treatment system, 2) expansion and improvements to the spray irrigation system and 3) in-plant process modifications. described and estimated costs for each are given.

Maximizing the nitrogen loading to a site

The measures taken are

BACKGROUND

Mott's Prepared Foods is a further processing plant that cooks dressed chickens and sells diced meat. Mott's purchased a red meat slaughtering plant in Talmo, Georgia in 1983 and began operation in 1982. The wastewater treatment system inherited with the plant consisted of a series of three lagoons (anaerobic, aerated and polishing) with plant effluent being discharged to a small stream having an average annual flow of approximately 850 l/s (30 cfs). In 1983 the Georgia Environmental Protection Division (EPD) issued Mott's a notice of violation for discharges in

P

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excess of NPDES permit limits. When effluent quality failed to improve in succeeding months the EPD drafted a Consent order which required Mott's to develop a zero discharge plan for wastewater treatment. were to conduct a detailed site investigation and develop a conceptual plan for land application of wastewater.

The first steps in this process

LAND APPLICATION SYSTEM DESIGN DEVELOPMENT

A detailed soil investigation was performed to determine if the available land at the plant site was suitable for wastewater application. several locations and four soil permeability tests were performed at the site. physiographic province which typically contains residual soils on the uplands that were derived from igneous and metamorphic rocks. the plant and the area tested for land application.

Soil borings were advanced at

Talmo lies in the Piedmont

Figure 1 is a site location map showing

1991 Food Industry Environmcntnl Confcrcncc

Three soils series were mapped on the site by the Soil Conservation Service. The Appling and Pacolet s o i l s derived from mica schist and gneiss and contain a sandy loam surface horizon and clay subsurface horizons, derived from granite gneiss and contains sandy loam horizons over relatively shallow weathered rock (<1 m), The permeability of the clay subsoil in the Appling and Pacolet soils averages 1 cm/hr. Depth to the water table is greater than 3 m throughout the area investigated. area investigated range from 5 to 30 percent, Based on the results from the soil investigation, approximately 10 ha (25 ac) of land at the site were determined to be suitable for wastewater irrigation. The only site restriction was that the steeper slopes (>12%) would have to be maintained in forest cover,

The Louisburg soil

Slopes in the

Limited data on wastewater quality and flow rates were available when the conceptual design study was performed. Based on three analpses performed in May and June, 1983, the average total nitrogen concentration was 32 mg/l. Measurements made at a weir located in the outlet structure from the aeration lagoon yielded an average flow of 160,000 l/d (42,000 gpd). Based on plans for increasing production at the plant, a design flow of 227,000 l/d (60,000 gpd) was used for calculating wastewater loadings. total annual nitrogen load from the plant using these figures was 1,900 kg/yr (4,200 lb/yr) .

The projected

An assessment of the nitrogen assimilative capacity of forest vegetation was performed to determine the land area requirement for application of the total nitrogen load. Studies at Penn State University (2) and the University of Georgia (1) and data published in the EPA Process Design Manual for Land Treatment of Municipal Wastewater (3) were used as the basis for estimating the nitrogen assimilative capacity of the proposed irrigation site. After accounting for all nitrogen pathways, including an estimated 20% loss due to denitrification, the nitrogen loading capacity was estimated to be 870 kg/ha-yr (780 lb/ac-yr). To assimilate the nitrogen load from the plant a land area of 2.2 ha (5.4 ac) was required.

In January, 1984, a 3.8 ha (9,4 ac) irrigation system was placed into operation. The irr igatior. systzm consisted of above-ground aluminum pipe laterals with galvanized steel risers. Impact sprinklers with flow restricters rated at 26 l/min (7 gpm) were designed to deliver effluent to the site at a rate of 0.45 cm/h (0.18 in/h). The system was divided into three zones with each irrigated twice a week for four hours per application. Above-ground piping was selected because it is easy to install in forested areas where slopes are relatively steep (20-30%).

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GROUND WATER MONITORING

All land application system permits require ground water monitoring to evaluate system performance. ground water monitoring program at the Matt's plant consisted of two wells located down-gradient from the spray irrigation system (M-1, M-2) and one background well (M-3) (see Figure 1). basis with analyses performed for pH, specific conductance, nitrate-nitrogen, chloride and COD. Nitrate-nitrogen, with a limit of 10 mg/l, is the most critical parameter in ground water monitoring programs for poultry processing land application systems.

The original

Monitoring was scheduled on a quarterly

/

Ground water samples were collected in September, 1983 before system start-up and analyses indicated that nitrate was at a concentration consistent with background levels. Results of nitrate analyses from ground water monitoring at all wells at the Mottls. site are presented in Table 1. June, 1984 after 6 months of operation the nitrate concentration in Wells M-1 and M-2 had already exceeded the drinking water limit of 10 mg/l.

By

In February, 1985, when the extent of the problem became apparent,: the Georgia EPD requested a study to determine the extent of the nitrate plume in the ground water. Two additional monitoring wells (M-4, M-5) were installed down-gradient from Well M-2 and were added to the monitoring program. Nitrate analyses performed in 4/85 revealed that the nitrate plume detected at M-1 and M-2 was of very limited extent. Ground water gradients were such that the nitrate plume was migrating toward Allen Creek where it presumably discharges as baseflow to the stream.

The measures taken by Mott's in an effort to remedy the problem of nitrate contamination in ground water are discussed in the remainder of this paper. made to the data presented in Table 1 in an attempt to correlate changes in ground water quality with wastewater system improvements .

Reference will be

WASTEWATER TREATMENT UPGRADE

Mofiftorfrq durii,g LL- ---&I- - 1 - 3

---2 - -- -3

LU~S UIUULIIS roiiowing cne ground water study continued to show elevated nitrate concentrations in M-1 and M-2. To a large degree this could be attributed to nitrogen loading in excess of the design capacity. In March 1985, an evaluation of water usage and wastewater flows revealed that flow data and wastewater characteristics used during the development of the conceptual design in 1983 were incorrect.

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Table 1. Nitrate-nitrogen Concentrations in Monitoring Wells.

Sample Nitrate-Nitrogen Concentration (mg/l) Date M-1 M-2 M-3 M-4 M-5

9/83 7/84 1/85 4/85 9/85 12/85 1/86 4/86 7/86 10/86 1/87 4/87 7/87 10/87 1/88 4/88 7/88 10/88 1/89 4/89 7/89 10/89

4/90 7/90

1/90

10/90 1/91 4/91 6/91

3 . 6 27 36

27 18 17 19 17 16 33 14 16 1 0 16 16 1 2 1 5 23 16 21 14 1 5 17 12

11

---

8 . 8

2 . 0 1 . 0

0 . 8 20 50

45 43 40 52 55 42 33 18 19

18 13 D 15 26 17 18 18 27 10 11 12 14

---

7 . 1

1 . 8 1 . 8

,002 1 . 2

< 0 . 1 < 0 . 1 < 0 . 1

0 . 2 6 . 0 6A1 D 5 . 2 5 . 1 0 . 2 0 . 2 D 2 . 3 0 . 3 D D 0 . 5 0 . 3 0 . 6 1 . 0 1 . 7 0 . 4 1.1 0 . 3 1 . 6 0 . 4 0 . 1

< 0 . 1 < 0 . 1

0 . 5 4 . 3 6 . 1 3 . 9 5 . 4 7 . 9 0 . 7 1 . 4 1 . 7 2 . 4 2 . 4 1 . 5 3 . 9 1 . 5 3 . 4 3 . 2 2 . 4 0 . 7 0 . 7 1 . 9 1 . 7 0 . 5 0 . 4 0 . 1

< 0 . 1 <0.1

1 . 6 2 . 0 4 . 8 3 . 7 6 . 1 5 . 8 0 . 7 0 . 9 1 . 4 1 . 6 2 . 2 2 . 2 2 . 2 2 . 0 2 . 1 1.1 0 . 9 0 . 9 0 . 4 0 . 6 0 . 6 1 . 0 0.5 0 . 1

* D: Dry well, no sample.

The original total nitrogen concentration data from May and June 1983 did not take into account seasonal fluctuations in the biological and chemical activity in the treatment system. species since system start-up are presented in Table 2 . The cyclical pattern in total nitrogen concentration can be attributed mainly to seasonal variations in ammonia-nitrogen concentrations. during the summer is due to volatilization caused by the slightly alkaline pH ( 8 . 0 ) and warm temperatures in the wastewater lagoons. Data that were collected in May and June, 1983 probably represented a lower nitrogen concentration than the average annual concentration.

wastewater cnaracteristics For nitrogen

It is likely that most of the ammonia loss

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Table 2. Wastewater Characteristics-

Concentration (mg/l) Date Total Organic NH3-N NO3 -N

N N

6/83 8/84 9/84 1/85 5/85 8/85 12/85 2/86 3/86 ' 10/86 1/87 4/87 7/87 10/87 1/88 4/88 7/88 10/88 1/89 1 4/89 7/89 10/89

4/90 7/90

1/90

10/90 1/91 4/91 6/91

35.2 43.9 40.5 34-1 31.1 28.9 54-9 53 66 45.5 55.9 46.4 17.4 . 54-0 64.0 78.1 18.7 54-2 90.5 68.8 19.1 57.5 63.7 57.4 27.1 39.8 62.8 81.2 28.1

32 -- -0

-0 -- -- 42 -- -- 9 11 6 4 11 10 16 8 9 6 23 7 6 4 11 9 9 4 36 8

3 -- -0

0- -- -- 12 -0 -- 24 34 40 13 27 57 62 10 36 81 45 12 50 59 46 15 30 58 45 20

0.9 -- -- 12.5 10.9 0.4 0.4 16.0 7.0 0-1 0.7 9.2 3.5 0.8 0.1 1-5 0.7 0.4 1.1 0.8 0.8 0.2 0.1

Irrigation records gathered during the first year of operation revealed that the flow estimates used for design calculations were low by a factor of two. Actual volume of wastewater applied during this period averaged 454,000 l/d (120,000 gpd) compared to the l6O,OOO L/d measured and 227,000 l/d projected for an expanded operation. The error in these numbers was traced to an improperly calibrated water level recorder in the weir box at the aeration lagoon. Application of twice the design volume at an average total nitrogen concentration that o u t 50 percent greater than projected resulted in a nitrogen loading that exceeded the design capacity of the 3.8 ha site-

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Data for annual wastewater volume and total nitrogen loading at the Mott's LAS site are presented in Table 3. 1985 through 1988, north Georgia experienced drought conditions during at least part of the year while in 1990 rainfall exceeded the average by a considerable margin. The lower volumes of wastewater applied to the LAS site from 1985 to 1988 can be attributed, in part, to the lower amount of rainfall interception, runoff collection and infiltration contributed to the wastewater lagoons. The reason for the low nitrogen loading in 1987 has not been determined since production from the plant during that year was within 10 percent of that during 1986 and 1988.

In

Table 3. Annual Wastewater Loading to Land Application Site.

Wastewate Volume Nitrogen Loading kg/yr lb/Yr Year lo6 l/yr 10 E gal/yr

1984 1985 1986 1987 1988 1989 1990

114 78 85 46 65 94 117

30 20 23 12 17 25 31

5,000 11,000 2,900 6,400 4,700 10,300 1,200 3,800 4,000 8,900

5,800 12,800 5,500 12,100

During the previous operation at'the plant a large mass of solids had accumulated in the anaerobic lagoon. Most of the solids going to the anaerobic lagoon from the Mott's operation consists of fat, oil and grease. In April, 1985, a 570,000 1 (150,000 gal) DAF cell taken from another plant operated by Mott's was installed to recover some of the fat, oil and grease from the waste stream. Approximately 8,000 1 of fat, oil and grease are-removed by this system on a weekly basis. The performance of the DAF cell could be improved by adding flow equalization and chemical flocculants but there has been no attempt to evaluate the cost-effectiveness of these improvements.

The solids accumulation in the anaerobic lagoon from prior discharges was so great that the ability of this lagoon to provide any level of treatment was questionable. In fact, during certain times of the year the solids may act as a source of nitrogen to the aerated and polishing lagoons. During the summer of 1985, Mott's contacted a rendering plant in the region to determine the potential for rendering the solids in the anaerobic lagoon. The oil and grease that liquefied and floated to the surface in the summer was acceptable, if it could be recovered, but the remainder of the solids was unsuitable. A preliminary

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assessment of the option to clean out the lagoon and land apply the solids was made butthe high cost and difficulty in locating a suitable site eliminated this option from serious consideration.

A study has recently been approved to evaluate the cost-effectiveness of upgrading the wastewater treatment system prior to land application. Future plans call for an increase in production at the plant which will increase the nitrogen load entering the waste stream. To handle this increase there must either be an increase in land area under irrigation or improvements made to the quality of wastewater applied to the LAS site.

LAND APPLICATION SYSTEM IMPROVEMENTS

The discovery of errors in the original wastewater characterization and the continued elevation of nitrate concentration in mon-itoring Wells M-1 and M-2 led to a decision in 1985 to expand the wastewater irrigation system. Approximately 10 ha had been identified as suitable for wastewater irrigation and less than 4 ha of irrigation field were constructed initially. development report, the Georgia EPD approved construction of two nek irrigation fields totaling 3.7 ha. all irrigation fields are shown on Figure 2 and the size and dates of installation are summarized in Table 4.

After review of a new design

The location of

A t the time of construction the vegetation in Expansion Zone 4 consisted of hardwood saplings remaining after a pine stand was harvested. Although the trees did not represent merchantable timber the dense growth was considered suitable for wastewater application. disposal of construction debris and worn-out equipment and was covered with a mixture of weeds. This zone was cleared, planted with a cover crop of fescue and rye then planted in pine seedlings in January, 1986.

have an immediate impact on nitrate concentration in the ground water (see Table 1). In fact, the nitrate concentration in Well M-2 continued to increase, reaching a peak of 55 mg/l in July, 1986. Irrigation on Zone 1 was discontinued in June, 1986, because of its proximity ta Well M-2- The loading originally applied to Zone 1 was distributed evenly to the other four zones. Shortly after this change in the operation of the system, the nitrate concentration in Well M-2 began to decline, By April, 1987 it reached a relatively stable level and for the next four years the nitrate concentration in M-2 averaged 16 mg/1. Although this was a significant improvement, the Georgia EPD insisted on further efforts to bring the nitrate concentration below the drinking water standard of 10 mg/l-

Zone 5 had been used for

The addition of Zones 4 and 5 in October 1985 did not

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Figure 2. Irrigation Fields

Table 4. Irrigation Field Area.

Zone Field Size No. Ha ac

Date Installed

1 2 3 4 5 6

Total Area

1.2 1.6 i.0 2.1 1.6 1.8 9.3

3.0 4.0

5.2 4.0 4.5 23.2

? E &.a

11/83 11/83

10/85 10/85

11/83

11/90

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Between January, 1988 and January, 1990, a series of modifications were made to the vegetation management system at the land application site. New pine seedlings were set out in January, 1988 in Zone 5 to replace the large number of trees lost in 1987 from excessive competition from weeds. Merchantable hardwood trees on Zones 1 and 2 were harvested in March of 1988 in an effort to develop a younger stand of trees with a greater nitrogen uptake rate. January, 1989 hybrid poplar cuttings were set out in Zone 5 to replace the pine seedlings that failed to survive from the January, 1988 planting. About 75 percent of the poplar cuttings survived the first growing season.

In

At the end of 1989, the lack of response in ground water quality after making the vegetation management improvements described above led to a decision to expand the irrigation system again. Plans were made to construct a sixth zone and abandon the forest management efforts on Zone 5. Both Zones 5 and 6 (see Figure 2) were to be converted to a double crop forage management sysfem consisting of bermuda grass overseeded during the winter with rye. By the end of 1990, a winter cover crop had been planted on Zones 5 and 6 and plans were also made to convert Zones 1 and 4 to the double crop forage system. Sprigging of bermuda grass in Zones 1, 4, 5 and 6 was conducted in May, 1991 and rye was overseeded in October, 1991.

concentration in Wells M-1 and M-2 was recorded (see Table 1). during the succeeding three months. attributed to the combination of more land under irrigation and a higher nitrogen assimilative capacity for the zones with forage grass cover. The addition of Zone 6 and the reactivation of Zone 1 increased the land under irrigation from 6.3 ha to 9.3 ha, nearly a 50 percent increase. Conversion from forest cover to forage grass on Zones 1, 4 and 5 increased the plant uptake of nitrogen from an estimated 170 kg/ha-yr (150 lb/ac-yr) to an estimated 670 kg/ha-yr (600 lb/ac-yr). Based on these projected nitrogen uptake rates for forest and forage grass management and giving allowance for denitrification and ammonia volatilization, the estimated nitrogen assimilative capacity of the LAS site is approximately 15,000 kg/yr. This is about 15 percent greater than the loading rate for 1990 (see

In April, 1991, a significant improvement in nitrate

Similar numbers were recorded for samples collected The improvement must be

T a b l e 3 ) .

The improvements made in 1990 and 1991 appear to have solved the nitrogen loading problem for the present. However, without additional land for irrigation, any increase in production at the plant could again raise the nitrate concentration in ground water at the LAS site.

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There is a small area northwest of the plant available for expansion of the irrigation system but the soil is shallow and buffer requirements limit the amount of useable land.

expansion of the irrigation system. considering soil and vegetation conditions, is a sod farm located to the southeast across Allen Creek. The major limitation for this site is that it is over 3,000 feet from the pump station. The next site in suitability is a cattle ranch immediately across Allen Creek from the polishing pond. The major limitation with this site is the problem of grazing management and concern about the liability if any of the cattle should die. available for purchase, is located adjacent to the Mottls property to the northwest. elevation than the;other potential sites and contains some of the same shallow soils as the remaining Mottls property, Plans are presently being made to evaluate the potential of the northwest property for LAS expansion.

Three new properties were evaluated in 1990 for The best site,

The final site, which may be

This site is at a higher

IN-PLANT NITROGEN CONTROL

The existing LAS site has reached its maximum capacity for nitrogen assimilation. the irrigation system Mott's decided to evaluate its operations to determine if there was any potential for in-plant reduction of nitrogen losses. sampling program was undertaken in the plant to identify principal sources of nitrogen. Test data indicated that there are three main sources of wastewater that contribute to the nitrogen load from the plant: 1) washdown water, 2) spillage from the cookers, and 3) overfilling of the evaporators. Data from the testing program are presented in Table 5.

Before going off-site to expand

In December, 1990, a

Table 5. Nitrogen Analyses from In-plant Wastewater Study.

sample 12/90 TKN Concentration (mg/l)

1/90 3/90 5/90

Washdown 85 Cook Room 1,700 Cooling Tower 18 0 900 20 <1

Washdown water represents the major source of nitrogen in the waste stream. estimated daily volume of 230,000 l/d (60,000 gpd). Composite samples collected from this waste stream on a flow

The washdown water represents an

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/

proportional basis in 12/90 yielded a nitrogen concentration of 85 mg/l. estimated to be 13 kg/d or 2,600 kg/yr.

The cookers have the highest nitrogen concentration but the only contribution they make to the waste stream is from spillage when the cooking baskets are first dropped into the vats. Spillage may amount to 150 liters per vat over the course of the day. With 30 cookers operating on a normal shift this waste stream represents about 4,500 l/d of wastewater. waste stream may contribute as much as 7 kg of nitrogen to the waste stream on a daily basis or 1,400 kg/yr.

process, also exhibited a high nitrogen concentration during early sampling. cooling tower contains only condensed steam pulled by vacuum from the evaporator. However, if the evaporator is over-filled with broth from the cookers, the excess broth is pulled into the cooling tower. At the end of each day the cooling tower, which holds about 40,000 1 of water, is drained to the process sewer. On occasion the cooling tower has become so full of broth that the piping would clog. At the maximum reported TKN concentration of 900 mg/l (Table 5) the cooling tower would contribute 36 kg of nitrogen to the waste stream on a daily basis or 7,200 kg/yr. from the maintenance supervisor put this source of nitrogen at about 20 percent of the maximum or 1,400 kg/yr.

the potential to reduce the nitrogen load in the waste stream by 40 to 50 percent. before a new basket of meat is dropped in, the vats can be Wopped upg1 after the meat is added, thus reducing spillage by 75 to 80 percent. monitored more closely the over-filling can be nearly eliminated. samples collected in 5/91 (see Table 5). Improvements to both the cook room and evaporator operation have been implemented but there has been insufficient data collected since these improvements were made to establish new nitrogen loading values for the land application system.

The nitrogen loading from this source is

Because of the high nitrogen concentration this

The cooling tower, which is part of the evaporator

Under normal operating conditions the

Estimates

Changes in the cook room and evaporation operations have

Rather than filling the cookers

If the evaporation process is

This improvement has been documented with

ESTIMATED COSTS

The estimated costs for construction of the various improvements at the Mott's plant in Talmo, Georgia are presented in Table 6. The costs for the original installation of Zones 1-3 includes material and labor for construction of the irrigation system including the pump station. The cost for the original installation of Zones 4-5 includes material and labor for irrigation construction

1991 Food Industry Environmental Conference

as well as land clearing and preparation. All other cos except for land clearing in Zones 1, 4 and 6 are for materials only because installation was performed by the maintenance staff at Mott's. installation of the DAF because it was transferred from another MottIs plant and installed by plant personnel. estimated cost for installing a used DAF tank is about $30,000. In-plant modifications were implemented at no except for wastewater analyses and engineering.

No cost is given for

'tS

!

An

cost

Table 6. Estimated Costs for Wastewater Upgrade

Item Cost ($1

Install Zones 1-3 Install Zones ,4-5 Reinstall Zone 1 Reinstall Zone 4 Reinstall Zone 5 Install Zone 6

28,000 24,000

4 ,000 6,000 5 , 0 0 0 10,000

SUMMARY

Control of nitrogen loading to the wastewater land application system has been an on-going project at the Mott's poultry processing plant in Talmo, Georgia. A 3.8 ha irrigation system was installed in 1984 and within 6 months nitrate contamination was detected in down-gradient monitoring wells. the irrigation system was expanded twice and several modifications were made to the vegetation management program. During the same period of operation a DAF cell was added to the wastewater treatment system and in-plant modifications were made to reduce the nitrogen load going to the land application system. The combination of these improvements has accomplished the goal of bringing the nitrate concentration in ground water to within drinking water limits. The most cost-effective method of nitrogen control at the Matt's plant appears to have been in-plant source control.

Over the course of the next seven years

The author would like to express appreciation to MottIs Prepared Foods and its parent company, Conagra, for granting permission to publish this study. Johnny Parr, Jerry Hill and Frank Smith at the Talmo, Georgia plant and to Larry Bost, former general manager at

Special thanks go to

Talmo.

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REFERENCES CITED

1. Nutter, W.L., R . C . Schultz, and G.H. Brister. 1978. Land treatment of municipal wastewater on steep forest slopes in the humid southeastern United States. p. 265-274. In H.L. McKim (ed.) Land treatment of wastewater. Vol 1. Cold Regions Research and Engineering Laboratory, Hanover, New Hampshire.

Sopper, W.E. and L.T. Kardos. 1973. Vegetation responses to irrigation with treated municipal wastewater. p. 271-294. In W.E. Sopper and L.T. Kardos (eds.) Recycling treated municipal wastewater and sludge through forest and cropland. University Press, University Park.

design manual for land treatment of municipal wastewater. EPA 626/1-81-013.

2.

Pennsylvania State

3. U.S. Environmental Protection Agency. 1981. Process

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