Performance Data

Mean performance data for 13 BIOLAC® systems are shown in Table 4.15, and monthly performance data are available in the USEPA (1990) report. All but the

Waste Activated

Along the Length of the Clarifier Hopper Bottom

FIGURE 4.22 Cross-sectional view of integral BIOLAC-R clarifier. (Courtesy of Parkson Corp., Ft. Lauderdale, FL.)

Along the Length of the Clarifier Hopper Bottom

FIGURE 4.22 Cross-sectional view of integral BIOLAC-R clarifier. (Courtesy of Parkson Corp., Ft. Lauderdale, FL.)

TABLE 4.15

Summary of Average Performance Data from BIOLAC® Systems

Influent Effluent

Flow % BOD BOD

Location Period Type (mgd) Design (mg/L) (mg/L)

Morgantown WWTP 4/89- R 0.29 58 243 12.7

(Morgantown, 9/89 Kentucky)

Greenville WWTP 5/88- R 0.40 55.3 178 6.2

(Greenville, 8/89 Kentucky)

(New Brockton, 8/89 Alabama)

(Edmonton, 11/89 Kentucky)

Fincastle WWTP 9/88- L 0.05 62.5 218 18.6

(Fincastle, Virginia) 8/89

Lowell WWTP 7/89- R 0.11 204 186 13.3

Hanceville WWTP 6/89- R 0.5 87.8 134 9.7

(Hanceville, 9/89 Alabama)

Loading

Removal d_1)

92.3 575

96.5 528

95.5 111.5

91.1 185

Influent Effluent

TSS TSS

188 11.7

213 12.4

257 10.7

266 18.4

190 21.5

172 26

Effluent

Removal (mg/L)

89.7 ND

Livinston Manor 6/86-

WWTP (Rockland, 8/89 New York) Blytheville West

WWTP (Blytheville, 10/89 Arkansas) Blytheville North

WWTP (Blytheville, 10/89 Arkansas) Blytheville South

WWTP (Blytheville, 10/89 Arkansas)

Arkansas) 9/89

Piggot WWTP 6/89-

(Piggot, Arkansas) 9/89

Source: Data reported by USEPA (1990); additional data available from Parkson Corp. (Ft. Lauderdale, FL).

ND 14.9

ND 26.3

ND 18.1

26.0

30.9

11.3

facility located in Fincastle, Virginia, are BIOLAC-R systems. All of the systems, with the exception being the plant in Piggot, Arkansas, produced an effluent that satisfied secondary standards of 30 mg/L of BOD5 and TSS. Most of these plants had been operating for only a few months, so the data may or may not be indicative of long-term performance. Richard H. Bowman (2000), with the Colorado Department of Health and Environment, has reported that the BIOLAC® systems in Colorado have satisfied secondary standards and ammonia nitrogen removal requirements where required for many years. Parkson Corporation (2004) reported that the Nevada, Ohio, BIOLAC® system (100,000 gpd) produced a 2-year average effluent containing 4.1 mg/L BOD, 6.9 mg/L TSS, and 0.7 mg/L NH3-N. Additional data available from the Parkson Corporation show BOD and TSS concentrations of less than 10 mg/L, ammonia nitrogen concentrations of less than 1.0 mg/L, and total nitrogen concentrations of less than 8 mg/L.

4.10.2.4 Operational Problems

The U.S. Environmental Protection Agency (USEPA, 1990) presented a summary of the problems encountered at various BIOLAC® plants. The difficulties appear to be typical mechanical failures and excessive debris and floating sludges with excessive oil and grease in the clarifier. Most of the problems appear to be correctable with routine maintenance.

4.10.3 LEMNA Systems

Numerous references to the use of duckweed in lagoon wastewater treatment systems date back to the early 1970s, but this discussion is limited to the application of proprietary processes produced by Lemna Technologies, Inc. (Culley and Epps, 1973; Reed et al., 1995; Wolverton and McDonald, 1979; Zirschky and Reed, 1988). Lemna Technologies offers two basic systems for wastewater treatment: the Lemna duckweed system, in which floating partitions keep the plants evenly distributed over the surface of the pond, and the LemTec™ Biological Treatment Process. In addition to these basic units, the company produces the LemTec™ Modular Cover System, Lemna Polishing Reactor™, LemTec™ C-4 Chlorine Contact Chamber-Cleaner, LemTec™ Anaerobic Lagoon System, and LemTec™ Gas Collection Cover. Lemna Technologies reported in a recent press release that over 150 municipal and industrial installations exist worldwide; it is assumed that the 150 installations include regular lemna and biological treatment process systems as well as the other systems produced by the company (Lemna Technologies, Inc., 1999a,b). The descriptions and discussions of processes in this chapter are limited to the Lemna duckweed system with floating partitions and the LemTec™ Biological Treatment Process.

4.10.3.1 Lemna Duckweed System

The duckweed system can be used in retrofitting an existing facultative or aerated lagoon system or can be an original design. An original design consists of a regular facultative or aerated lagoon followed in series by Lemna system components, including a floating barrier grid to prevent clustering of the duckweed and baffles to improve the hydraulics of the system. These basic components are followed by disinfection, if required, and reaeration of the effluent that is anaerobic beneath the duckweed cover. A diagram and flow scheme for a typical Lemna system design are shown in Figure 4.23 (Lemna Technologies, Inc., 2000). The Lemna system has been installed in several locations, ranging from Georgia to North Dakota in the United States and in Poland in Europe. Flow diagrams of several of these systems are shown in Figure 4.24

For the Lemna system to function properly, it is necessary to harvest the duckweed on a regular basis. LemTec™ harvesters are available for use in ponds utilizing the floating barrier grid to ensure even distribution of the duckweed (Figure 4.25). The harvesters operate by depressing the floating barrier and removing the duckweed from the water surface. Biomass harvested from the Lemna system can be managed via land application of the duckweed, composting the duckweed, or the production of pelletized feedstuff. Other than land application, these management methods can be expensive, and additional data are required to evaluate the economic feasibility of these two options.

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