66    TREATMENT OF CARBAMATE INSECTICIDE RINSATES
USING MEDIA FROM THE MUSHROOM PRODUCTION
INDUSTRY
VVen-Shiuh Kuo, Research Assistant
Raymond W. Regan, Sr., Associate Professor
Department of Civil and Environmental Engineering
The Pennsylvania State University
University Park, Pennsylvania 16802
INTRODUCTION
The widespread use of pesticides throughout the agricultural industry has resulted in mixed
impacts. On one hand, pesticides increase agricultural productivity. On the other hand, because of
their hazardous nature, the wastes and rinsates from spray and storage equipment have been sources
of surface water and groundwater contamination. Carbamate insecticide (a major class of pesticides)
residuals have been found in drinking water, surface water, and groundwater. For example, carbo-
furan has been detected in some treated public water supplies.1 Carbaryl at a concentration of 3 ppb
was detected in stream water.2 Aldicarb has been reported to contaminate groundwater.3
Farmers and commercial applicators have been given little information on what to do with
pesticide-contaminated wastewater which includes unused tank mixed pesticides and rinse water used,
to clean application equipment and containers, herein collectively referred to as rinsate. Rinsates may
be generated at scattered or remote sites, making transportation and decontamination using approved
methods difficult and costly. The most commonly used disposal techniques by farmers include simply
applying the rinsate at a suboptimal dose, letting the contaminated water fall onto the soil surface in
an uncontrolled manner or, discharging to an evaporation pit. Evaporation is not an effective alternative because the residual affords a slurry of highly concentrated waste. The development of economical and practical on-farm treatment techniques for pesticide rinsates remains a significant challenge to
the agricultural community.
The study's objective was to investigate the feasibility of using spent mushroom compost (SMC) as
an adsorption medium and as a microorganisms source to remediate carbamate insecticide rinsates in
a completely mixed batch reactor (CMBR) for on-farm use. Three widely used carbamate insecticides,
namely carbaryl, carbofuran, and aldicarb [molecular structures are shown in Figure 1], with a
concentration range of 0-30 mg/L, were selected for adsorption and biodegradation studies.
BACKGROUND
Characteristics of Spent Mushroom Compost
SMC is the major residual solid waste of the mushroom industry. About 35 million cubic meters of
SMC were produced in the United States each year.5
SMC consists of 20% organic matter including cellulose, hemicellulose, lignin, and some residual
nutrients such as nitrogen and phosphorus. Some studies6"11 have indicated that the organic matter in
soils or sediments contributes significantly to pesticide adsorption, especially nonionic organic compounds. Based on these previous studies, it would be expected that the adsorptive capacity of SMC for
pesticide would be greater due to its increased organic content compared to most soils.
Although the industrial practice has been to sterilize the SMC prior to disposal, 24-30% of the
microbial population (bacteria, actinomycetes and fungi) survive.12 Some survival species including
Aspergillus flavus, Aspergillus terms, Mucor sp., and Trichoderma viride have been reported to be
active for carbamate insecticide.13 In addition, because some pesticides including Diflubenzuron
(Dimlin), Sodium Hypochlorite (HTH), Diazinon, Chlorothalonil (Bravo), Benomyl (carbamate pesticide),  Permethrin  (Pounce or Ambush),  Thiobendazole (Mertect) and Propoxur (Baygon —
48th Purdue Industrial Waste Conference Proceedings, 1993 Lewis Publishers, Chelsea, Michigan 48118. Printed in
U.S.A.