Vasluiet River on the outskirts of Vaslui

The first ecotechnical method

Ph.D Razvan Voicu

rzvnvoicu@yahoo.com

Vasluiet River is polluted with organic substances coming from the wastewater

treatment plant of the city of Vaslui. We must find solutions for wastewater treatment.

One solution would be the FLOATING GRIDS. This floating grid can be made of

bamboo or any other material and has a metal waterproof outer frame. The outer frame is

fastened to some bars fixed in the bank of the river, which, in turn are provided with a

fixing system of grids so that they can slide according to the water level.(fig.1).

streambank

metal frame

floating elements

metal bars fixed in the riverbed

floating elements

plastic bearings

metal bars fixed in the riverbed

metal bars supporting the floating grid

Figure 1 Solution for wastewater treatment

This grid of floating elements should support the floating plants called Eichhornia

Crassipes (Water Hyacinth), Pista Stratiotes (Nile Cabbage) having excellent depolluting

functions. These aquatic plants successfully carry out their depolluting functions between

15 and 34 degrees. Therefore, they should be covered if any continuous operation in a

channel or pond is necessary.

The technology used involves the use of aquatic plant species, active links of food

chains, which are characterized by bioconversion processes and bioaccumulation.

If appropriate, harvested biomass, after performing the physico-chemical and

biological analysis, is directed to various fields such as: adjuvant in animal feeding,

extraction of pigments, retention in methane fermentation, achieving a germinating bed

for rehabilitating the degraded land, formation of silos with straw. There were obtained

good results using these aquatic plants in our country. Plants are placed into the

rectangles of the floating grid; they grow up and will soon form a floating carpet for

water purification (fig.2). floating grid

Figure 2 Water purification system

On the entire length of river channel Vasluiet having about 600 feet, minimum 20

floating grids of 10 meters length shall be made in order to purify plenty of water in this

river sector. These floating grids will be up to ten meters in order to be lifted with a

special crane, unloaded, put back with the amount of plants required. To run all year, this

riverbed sector should be covered by a cupola made of glass or transparent plastic that

allows plants to receive the necessary light. Temperature must not fall below 15 degrees.

External opening windows in the cupola must be made for ventilation. During the winter

heating should be placed inside the dome. Also, cupola (Fig.3) must be equipped with

multiple doors where staff can enter to collect plants, as the process of lifting the grating

with the crane is no longer viable in winter. Cupola must be removable for the warm

period.

external opening windows

cupola for plants operation

floating elements

metal bars attached to bed

Figure 3 Way to plant winter operation

A chart of energy costs consumed during winter, but also of damages caused by

pollutants must be made, and according to these the construction of cupola, which works

in winter, will be decided.

The second method

Consolidation method regarding the banks of Bârlad River in the village of Stefan

cel Mare, Vaslui County. There are detachable sections of Bârlad riversides in the village

of Stefan cel Mare, therefore there is risk of falling into the river blocking the water

course(fig.1,fig. 2).

Bârlad River

the displacement of the left bank

Figure 1

Bârlad River

the displacement of the left bank

Figure 2

For both cases of dislocation of banks, a reliable ecotechnical method was

developed.

Methods for Verticalization and Inclined Planes

For its stability, the bank must be verticalized up to the cracking from the inside

and then, from the same point, an inclined plane to the river Bârlad must be executed (fig.

3 si fig.4).

cracking in the riber bank

Bârlad River

Figure 3 The current status of the Bârlad river's banks in the village of Stefan cel

Mare

wooden sheet-piles

dowels

Bârlad River

riparian

vegetation

Figure 4 Ecotechnical method for reconstructing the left bank of the Bârlad river

in the village of Stefan cel Mare

The verticalized area will be strengthened by wood piling secured by durable

plastic dowels, and various plants, including trees (alder, acacia, etc.) will be planted on

the inclined plane in order to stabilize the river bank. The works will be carried out by the

means of some mechanized equipment. On both areas characterized by sliding sides, the

same type of work will be carried out.

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2011