Measurement of Water Quality Parameters. The various sam ples necessary for the analysis of the physical, chemical, and biological parameter s were taken in com pliance with inter national standards for water analysis (ISO 5667). Five replicates were made for eac h measure ment. All of the parameter s comm only used to assess the performance and treat ment capacities of such systems were examined (stan- dard method nu mber follows eac h parameter in brackets). They includ ed p H (NF T90-008), dissolved oxygen (ISO 5814), tota l suspended solids (SS; NF EN 872), chemical oxygen demand (COD; ISO 6060), and biochemical oxygen demand (BOD5; ISO 5815). Total nitrogen conce ntrat ion (TN) in water was measured by spectro ph oto metric assay (Genesys 5, Spectro nic, Rochester, NY) after pota ssiu m peroxodisulfate digestion (ISO 7890-1). Total ph osph orus conce ntrat ion (TP) in water was measured according to standard ISO 6878 by spectro ph oto metric assay using ascorbic acid and after pota ssiu m peroxodisulfate digestion. The conce ntrat ion of NH4+-N was deter mined by spectro ph oto metric assay according to standard ISO 7150-1.

The conce ntrat ions of NO3--N and NO2--N were de- ter mined by capillary electro ph oresis using a Beckman P/ACE system 5510 equipp ed with a diode array detector . The capillary (Beckman, Fullerto n, CA)  was 60  cm long (54  cm

where  C(t) is the  efflue nt conce ntrat ion ( mg L-1) at  time  t,C1 + C0 is the initial influe nt conce ntrat ion ( mg L-1), C0 is the final influe nt conce ntrat ion at infinite time ( mg L-1), k is the first- order reaction rate constant (h-1), and t is  the treat ment time (h).

Statistical Analysis. Principal com ponent analysis (PCA) was performed using STATLAB software on all parameter s for the control system of chann els with plants (12 variables, five sam ples at six differe nt times; i.e., 30 inpidua l ite ms). This factorial analysis helps und erstand how depollution in plant systems occurs by evaluating the links betwee n the differe nt parameter s and any similarities betwee n the dif- fere nt sam pling times (20).

Growth Measurements and Water Relati ons. At the end of the experimentation, 5 plants per treat ment were harvested and separated into shoot and root parts, and the fres h weights were deter mined. The dry weights were obtained by drying the plant for 72 h at 85 C. The water conte nts (WC) of the plants were  deter mined using the following equa tion:  WC) ((fres h weight - dry weight)/ dry weight) × 100. Shoot length was evaluated using 6 plants per treat ment.

Chlorophyll a Fluorescence Measurements. The chloro- phyll a flu oresce nce has bee n ret ained as a physiological refere nce parameter to follow eventual str ess du e to plant culture on wastewater. A wide range of labo rato ry studies have estab lished that chloroph yll a fluoresce nce is a sensitive and early indicato r of da mage to ph oto synthesis and to the plant physiology res ulting from environ mental str esses (21- 23). It provides information on the inhibition or da mage occurring in the tra nsfer of the electro ns from ph oto system II (ΦPSII) on ph oto chemical qua ntum yield and is a sensitive indicato r of ph otoinhibition. In add ition, the measure ment of chlorophyll a flu oresce nce is both nondestr uctive and noninvasive. Fluoresce nce parameter s were measured on intact leaves of 20 plants of Chrysanthe mum cinerariaefoli um, with a pulse am plitud e modulation portable flu oresce nce monitoring system (PAM FMS, Ha nsatech Instr u ments, Norfolk, U.K.). The parameter s used to define the yield and qu enching mechanisms of chlorophyll a flu oresce nce were

∆F/Fm, qua ntu m yield of electro n flow throughout ph oto- system II (ΦPSII); Fv /Fm, maximal ph oto chemical efficie ncy of  the PSII,  measured in  predarkened (for  30  min) leaves

(24).

Assay of Pyrethrins. Flowers at the same stage of develop ment were collecte d after 5 months of treat ment. Pyret hrins were extracte d and analyzed as previously de- scribed (25). At least six replicates were used for eac h measure ment.