BIOMINERALIZATION AS A SAFE, AND CLEANPROCESS FOR THE ENVIRONMENT TO REDUCE

CALCIUM CONTENT, EMISAL,FAYIOUM ,EGYPET.A.M,WALI , Y, SAMY , R,M ELSHEIKH AND A,M,ABD

ELTAWAB

I - Review and ScopeBiomineralization as a safe, and clean process for the environment was along lasting natural process, acting and functioning whenever therequirements are available. These are mainly:

1. solar energy.2. salinity.3. aqueous media.

The main factors are best representative through salinas at the arid tosemi-arid zones (management of salinas permits steady control onsalinity and regular salinity gradient can be achieved). Moreover, toterminate the process, the increase in salinity will be the key. So, the

specifications (TDS ≈ 125 g/l, and pH ≈as a concept was quiet old. Many trials through basic branches of lifeforms were reviewed by Muller (l777). By the 18th century, the scopewas more virtualized by many authors, among them Ludwig and Thobald(1852), where trials for the mineralizing plant by calcium carbonates andbicarbonates was in the scope. Continuation with flourishing scientificknowledge and feature analysis (e.g. the biopopulating forms wheneverthe waters terns to saline or swampy conditions) was the motive toreview and to understand as well many features existed, but were notunderstood. The field of microbiology; cell chemistry and biochemistrywas the link to understand the species and its range of adaptation to acertain function. The function was existed unplanned (no interference),and this was the entrance to interfere with experimental motives as tounderstand the procedure that governed the function. At this criticalmoment, the directed functions were applied with modernization andindustrialization process. Also applications were getting wider and it will

continue so as long as demand is existing. Cell physiology was the targetof many authors as to create functions for the biomasses that in manytrials were governed by slavery thoughts. Among these manyapplication, mineral enrichment was one of the branches that attractsmany biologists and consequently mineralogists (e.g. Beveridge et. al.,1983; Lowenstein, and Weiner, 1983; Ferris et .al.,1986; Krumbein.1979, 1986 a and b ; Beveridge, 1986 and 1989; and Reineck et. al.,1990). The experimental fields were of special emphasis directed tobacteria (one of the main reasons is its reproductively and surface area) ,and brine flies. Both were representing the material intensively appliedin recent years as one among others for Biomineralization function. Thisfield seems never to stop gazzling look of scientists hence. Manythoughts are now drastically turning so acute and in so short time as torase up the level of results to a wonder category.

Salinas are now the target for many biomineralization functions, hencethe following facts can’t be avoidable:

1- Continuous demand for salts is steadily increasing.2- Industrialization rate is now reaching jumps rather than

development.3- Link between synthesized salts and new industrial application is

getting stronger with time.4- Metal enrichment through bioreactions is the gate for many low

grade ores.5- Bio-leaching andlor bio-enrichment processes are definitely safe

for the environment.

Moreover, the concentration ponds type of salinas are a new version ofthe precipitation salinas with non-comparable accelerating rates toproduce salts industrially. This view is adopted quiet recently hence thepermitted area is always shrinking. EMISAL is the pioneer in this field asto produce anhydrous sodium sulfate from concentration ponds. Thechemical composition of the Quarun Lake is changing as a result of agroup of variants, among them is the drained out agricultural wastewaters to the lake. Also, the Un- adjustable quantities of fertilizers usedfor agriculture purposes is another important factor. The chemistry of

the lake show remarkable difference in salinity; Cl and Na through thelast three years (Tables- 1-3). This defmetly will posses an impact on thechemistry of the brine itself (compare the same elements within pondnos. 1 and 2, tables-4-9).

II - MethodologyThe seeding of the biomasses were flourished in the three sites of pondno.2 (Fig. 1). The biomasses are mainly: cyanobacteria, sea grass, and agroup of brine flies (salt beetles type). seeding starts at the periphery of

starts, the mineralized part is heavier in specific gravity, hence it tiltswith differe

Moreover, to follow the process as a net result of :biodegradation; layeraccumulation; and al mat (former known term was stromatolite). Thealgal mats were detected in pond nos. 2 , 3, and 4 (Figs. 5 and 6,represent the recent and the old analog) surrounding the pondperipheries.

The sampling sites (three sites, Fig. 1) were possessing a range in salinitybetween 100 - 110 g/l and, pH ranges between 8.1 and 8.2. Thesespecificaons wi ll gr ant the obt ai ned CaCO3 crystal s (as a tar get of theprocess) to stay on the media without dissolving. The collected sampleswere taking into consideration both the living biomasses and the surface

from the living biomasses were executed as follows:

1- collection of the mineralized cyanobacteria.2- washing, dissolving, and separation of the CaCO3 crystal under a

tap water with silt sized sieves.3- the collected crystals were tested posive for 5%, and 10% HCl,

and the effervescence vapor was tested by lead acetate paperwhere the color turns black at once indicating organically releasedgases as H2S.

The surface veneer samples were washed following decantation methodto remove the clays. Washed by tap water and then distilled water anddried up. The collected samples were tested posive wi th 5% and ١٠ %HCI, and then the effervescence gases were tested by lead acetate paperwhere the color turns also black.

Both samples were examined microscopically and then surveyedtentatively by the SEM. Microscopically, the samples were indicatingsimilarity from the three sites and from the living biomasses and bottomsamples as well.

III - Results and DiscussionsThe following features were reported through the field, microscopic, andSEM investigations:

A -Field investigations

1- Tables 1 - 3 indicate the change in monthly chemical composion ofLake Quarun. It was observed that the TDS, S04, Cl, and Na contentsare changing upwards.

2- Consequent expectaon of changes in pond no. 1 (Tabl es 4 -6) wasproved positive. This concerns: a- TDS value where salinemanagement was heading to lower down the TDS of the pond(Tables 4-6 for comparison), also the pH level was heading moretowards alkalinity, b- slight lower down in the values of C03 and Cawas achieved (Tables 4-6), and c- S04 content was also loweredwhich permits more oxygenation to the pond, if we comparedresults of 1995 and 1996 (tables 5 and 6).

3- Pond no. 2) seeding site) was chosen according to many factorsincludes salinity, pH, flow dynamic pattern, and oxygen content.The recorded Na content was also lowered comparatively with thatrecorded from 1994 and 1995 (Tables 7-9). Personalcommunication with Dr.S.Schultz-Lam, 1996 was leading to acommon understanding that the reached Na content although it ishigh, but the process of mineralization in such a level is unique.

4- Remarkable decrease in C03 content was observed through 1994-1996. It worth menoni ng that 1996 i s the j udgi ng fiel d for theprocess (Tables 7-9).

5- Ca content is also decreased as a result of biomineralization.Although the content of Ca is increasing in the Lake Quarun (Tables1-3), the recorded concentraon of Ca thr ough pond no. 2 from1994-1996 is decreasing (Tables 7-9).

B - Microscopic and SEM investigations

Under the microscope, the collected samples (living biomass, andbottom surface) were giving identical examination results, except for theclay fraction associated with the bottom samples. The examinationrevealed the following:

1- Pure crystals of aragonite were detected as pyramidal;bipyramidal; and hexagons (Deer et. al., 1980, and possessingdifferent sizes (Figs. 7 and 8). Admixture of clay coat is sl ldetectable as a result of probable adhesive character of thebiodegraded clays on the surface of the aragonite crystals.

2- Closer view (Figs. 8, 9, and 10) indicate the different sizes ofaragonite, but all of them are of clear and perfect crystal faces.Some twins) Fig. 9, arrow) are detectable and the direcon ofgrowth is parallel to 010 face (Deer et. al., 1980). A more closerview (Figs. 11 and 12) indicate daughter growing crystals followingand controlled probably by the cell structure. Figure 12 is showingthe twinning character with clear over-pressured features as aresult of free-competitive growth manner (this manner is believedto be the responsible mechanism for the dome-like patterndisplayed by recent algal mats, Fig. 5, as confirmed by personalcommunicaons wi th Pr of .B. C. Schr ei ber , 1996 ).

3- Microscopic examination of the bipyramidal prismatic crystals ofaragonite (Figs.13 and14) indicate a root-like outlined crystals.This character is reflecting the perfect crystalline patterndisplayed by aragonite, while the root part indicate the nucleusfrom which the crystal is growing as a nucleation center(cyanobacterial structure always reflecting layered pattern

initiated from a smaller nucleation cell as a center (personalcommunication with Dr. S.Schultz-Lam, 1996). The closer view(Fig. 14) indicate the existence of relics of mineralized cells of thecyanobacteria (Fig. 14, arrow). This was confirmed through SEMexaminaon, wh er e F i gs. 1 5 a nd 1 6 i ndi cat e a g r owi ng u paragonite crystal including relics of cells on the growing crystalsurface. The close up view (Fig. 16) clarify the process, where thecells are seen penetrating the surface of the growing up crystal ofaragonite.

4- Clear features that eliminate doubts about the bio-influence in themineralizaon pr ocess is cl ear l y pr esent ed in Fi gs. 15, 17, 18, and

biofilamenteous pae r n. A c l os er v i ew ( Fi g. 17) i ndi cat e t hepresence of minute crystals forming the capsule. Figs. 1 8 and 19(general view and the close-up) are a more supportive criteria,where the bio-filaments (mineralized), are lining growingaragonite crystals (Fig. 18, upper right). The capsules are .ntsjzes(Fig. 15), while their siz is d the result i me wi thi n wh i ch sal ini tyand chemical composition of the brine was maintained steady.This is supported by Fig. 20, different sizes of growing up capsulesare seen entrapping even aragonite crystals, that most probablywhy the capsules are not following a regular outline. More,surprises were obtained through SEM investigations of the scalesinside the anhydrous sodium sulfate plant, where similar if notidentical features of capsulation and mineralized filaments werereported (Wall, 1996).

Discussions about the process definitely will lasts for some time, but theobtained facts through the recorded features is the key to directdiscussion through the line of how to explain and never to deny. Startingfrom this issue the Ibilowing points are presented:

1- The range of capabilities of the involved biomasses in the processof biomineralization are still not totally understood. Also, thephysiological behavior of the cell functioning during its turn-overfrom life into a crystalline form is still amazing. But the range ofwonder is getting narrower hence bacteria (through its layers) are

a functioning factory for entrapping some minerals (simpletranslation for geological sense is mineral enrichment). This field isspreading with gratitude to many microbiologists and geologists,among these names are e.g. Ferris et. al., 1988; FelTis andBeveridge, 1986; Savage and Fletcher, 1985; Babich and Stotzky,1985; Beveridge, 1981 and 1984; Walker et. a!., 1989; Bathurst,1971: Boon, 1984; Buick, 1984; Dexter-Dyer et. al., 1984; Gerdeset. al., 1985; Kinsman and Park, 1976 and Schultze-Lam, 1992,1994, and 1995.

2- ٢- The obtained results were proved positive hence, the Cacontent reaching pond no.4 was not crossing the 200 ppm as thedesigner was appointing for the brine quality to be processedindustrially.

3- The print of the former existence of mineralized biomasses (Fig.6), direct the ae non as to under stand t he devel opmen t of theprocess, where the ideal theater is always the salinas due to thepossibility of reaching saturation levels and consequently theprecipitates are the product. Moreover, the older sequencesshould be overlooked through the relics and/or diageneticfeatures as a clue to understand the range of biomineralizationthrough the geologic history.

IV - ConclusionsThis article is the first results obtained in industrial salinas as to leachcertain elements that causes industrial troubles, especially if the feedingsource (Lake Quarun) is chemically changing within short time intervals.It worth to highlight the following points:

1- Biomineralization as a process was proved successful in the caseof EMISAL concentration ponds.

2- The obtained results will urged the authors as to explain moredeeply the physiological mechanism of the involved biomassesfrom the point of exploring their capabilities to serve other fieldsin mineral processing.

3- The fields within which the process can serve as a solution shouldbe surveyed more tentatively.

4- The re-evaluation of ores that could be accumulated in salineenvironment should also be reviewed.

The most valuable achievement is the existence of new scope withindustrial application. as a trend to be follow in the future. Also, theprocess proved its economic cost, and more important is its safety forthe environment through application on industrial scale.

V- AcknowledgmentsThe authors are greatly indebted to Prof. A.A.Dardir fbr the permit,confidence, support, and facilities during the field investigations atEMISAL salinas. Also we would like to thank Chem.T. Ramadan for help.

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Figure Captions

Figure 1: Locaon ma p of EMI SAL sol ar concent raon pbnds site. Figur e2: Growing up seeded bioinass, pond no.2.

of cyanobacteria), pond no.2.

Figure 4: Totally mineralized cyanobacteria, pond no.2.

Figure 5: recent algal mat, showing domal pae r n as a resul t of free -competitive growth manner, pond no.2.

Figure 6: Crystalline gypsum displaying domal pae r n (Cavol i structur e) .N.B. the lower most is including mineralized bio mass. pond nos. 3 and 4.

Figure 7: Microscopic photograph of collected aragonite crystals ofdifferent sizes. N.B. some crystals are coated with clay film, pond no.2.Polarized light. Bar scale is 250 u. Figure 8: Microscopic photograph ofaragonite crystals showing bipyramidal prism form, pond no.2. Polarizedlight. Bar scale is 100 u.

Figure 9: Microscopic photograph of pseudo-hexagonal aragonite, andtwin crystal (aiiow), pond iio.2. PolarizC(l light. Uar scale is I 0() u.

Figure 10: Microscopic close up photograph of pseudo-hexagonalaragonite crystal, pond no.2. Polarized light. Bar scale is 50 u.

Figure 11: SEM photouraph of growing aragonite daughters causing theclomal form. NB. hexagonal form is detected, pond no.2. X

Figure 12: SErV photograph of aragonite cry.st over-pressure growtkfeatures, pond no.2. X 500.

Figure 13: Microscopic photograph of bipyramidal aragonite crystal withroot-like end. pond no.2. Polarized light. Bar scale is 100 u.

Figure 14: Microscopic photograph (close up of Fig. 13) showing therelics of biomass cells (arrow), pond no.2. Polarized light. Bar scale is 25.

Figure 15: SEM photograph of aragonite crystals with relics of cells at thecrystal surface. N.B. mineralized capsule (le si de) , pond no. 2. X 350 .

Figure 16: SEM photograph (close up of Fig. 15) showing the relics of thebiomass cells, pond no.2. X 500.

Figure 17: SEM photo raph (close up of Fig.15) showing the mineralizedsurlàce of the capsule, pond no.2. 100

Figure 18: SEM photograph of aragonite crystals lined with mineralizedbiofilaments, pond no.2.X 1000.

Figure 19: S photograph (close up of Fig. 18) showing the minerbiofilaments, pond no.2. )&2Q

Figure 20: SEM photograph showing dense pae r n of caps ul e encl os i ngaragonite crystals, pond no.2. X 350.