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Typical State-of-the-Art

Researches & Applications of

Environmental Biotechnology

in the Philippines

 

By Wilfredo I. Jose

Associate Professor and Chairman, Department of Chemical Engineering, 

University of the Philippines, Diliman, Quezon City

 


 ABSTRACT 

Biological waste treatment processes such as the activated sludge process, fixed film processes, and biomethanation use naturally-occurring microorganisms. However, by inoculating these systems with especially adapted and cultured microorganisms (a process known as bioaugmentation), improvement: of the biological floc formation, reduction of sludge output, and increase in process efficiency result.

The following wastes were considered for treatment:

  1. Dairy and coffee wastes

  2. Textile wastes

  3. Fish canning wastes

  4. Agricultural chemical wastes

  5. Distillery wastes

  6. Swine wastes for biogas production

Two new biogas digester designs are also presented.


 INTRODUTION 

Environmental protection is the concern of every government since the resources of the environment determines the bases and limits of economic development. The Philippines is also concerned and environmental legislations are being updated.

Industrial microbiologists have recognized the usefulness of microorganisms in waste treatment since 1914, with the development of the activated-sludge process. This process depends on mixed culture of naturally-occurring microorganisms. Each strain has the ability to degrade a component or the waste material and to coexist together. An advancement was to improve the sludge by inoculation with a desired mixture of microorganisms. At present, pure cultures that are able lo degrade specific compounds in industrial wastes are available commercially. These are naturally-mutated strains or microorganisms available in liquid or powder form ready for application. The state-of-the-art process in biological waste treatment is supplementing the natural bacterial population with those that are capable of higher rates of reduction or capable of degrading compounds that have been previously considered non-biodegradable. With genetic engineering, particular microorganisms can be tailored to degrade particular types of wastes.

This paper presents some results and on-going researches on the use of microorganisms on the wastes/wastewaters or some industrial plants in the Philippines. New biogas digester designs for swine wastes and liquid organic wastes are presented also.

Water Pollution Control

Water pollution control procedures can be grouped as mechanical, chemical and biological methods. Mechanical methods include screening, sedimentation, flotation and filtration. The chemical methods are neutralization, oxidation, reduction, precipitation, flocculation, coagulation and emulsion-breaking. The biological methods employ the action of naturally-occurring microorganism and include the activated sludge process, trickling filters, and fluidized bed systems among others. The process could be aerobic, anaerobic, anoxic or anaerobic-aerobic combination.

Only the organic wastes are amenable to biological treatment processes although some microorganisms are able to adsorb toxic metals. The use of especially cultured bacteria are applicable for three cases: 

  1. Plants with existing biological processes, 

  2. Plants using chemical methods that can be converted to biological processes

  3. Plants without treatment facilities. 

The three types of plants are represented in the wastes considered in this paper.

 MATERIALS AND METHODS 

Microbial cultures used

Commercially-available microbial strains marketed as the NS Series were provided by Nu-Genes Technologies, Inc. Each of the series acts on a particular type of waste. The culture powder consists of two or more strains of the following microorganisms: 
Bacillus subtilis, Bacillus Lichenformis, Bacillus polymyxa, Bacillus megatorium, Aspergillus oryzae, A. niger, Lactobacillus acidopilus, Streptococcus lactis and Rumenococcus allus.  The cultures are guaranteed salmonella-free. The product acts as a microbial seed and the microorganisms multiply within a waste treatment system. They produce degradative enzymes such as amylases, proteases, lipases and cellulases. Thus, the product is effective in preventing occlusions, attacking organic impediment, and degrading wastes.

Procedure for Treatability Study.

The steps in determining the treatability of a particular wastewater is given below. The aeration vessels used are glass tanks that measure 18 cm x 18 cm x 66 cm. Aquarium air pumps are used for aeration. The procedure is:

  1. Place 10 L .of raw wastewater in each of two tanks labeled as "treated" and "untreated".

  2. Analyze the raw wastewater for different parameters such as BOD, COD, pH, suspended solid, and dissolved solids.

  3. Aerate the tank for 30 minutes.

  4. Inoculate the tank marked "treated" with microbial strain and continue the aeration of both tank.

  5. Collect and analyze samples from each of the two tanks every 12 hours up to the 48th hour, when aeration is stopped and the sludge allowed to settle.

Procedure for Bio-gas Production.

Swine wastes of one-year old sows were collected from the Bureau of Animal Industry in Alabang, Muntinlupa, Metro Manila. Two batch digestion were run with one treated with the NS series microorganisms. Before seeding, the digesters were purged with carbon dioxide and filled with 10 ml buffer solution (NaHC03) and 50 ml feed slurry. Approximately 500 ml of inoculum obtained from the Industrial Technology Development Institute (ITDI) was quickly added to each digester and its volume was then adjusted wvith tap water to the desired level. Gas production usually started one or two days after seeding. Thereafter small volumes of feed slurry were loaded daily (for about 20 days) until approximately 40 g total solids per liter digester volume has been added. During each loading a volume of the
supernatant equal to the feed volume was displaced.

Prior to loading, the digester contents were not mixed in order to avoid excessive washout of active microbial biomass. The digester pH was regularly monitored and adjusted during the 20-days period using 1 M NaHCO3 or 1 N HCl. The gas production, methane content, temperature, pH, total solids and total volatile solids were obtained. 

Analytical Procedures

Standard Methods for wastewater analysis were used. (APHA, 1981). The biogas composition was determined chromatographically using a thermal conductivity detector and Porapak N (mesh 100-120) packing material.



 
RESULTS AND DISCUSSION 


Coffee and Dairy Wastes

A coffee and dairy plant for many years has experienced problems in .their activated sludge system due to surge loads in production schedules. Filamentous growths resulted in sludge bulking. 


Fig. 1 

shows the schematic diagram of the treatment plant. Part of the problem is due to the inadequacy of the four aeration tanks. A treatability study was conducted using the NS series micro- organisms. 

 

Fig. 2 

shows the reduction in COD, total solids, total volatile solids and suspended solids. Bioaugmentation resulted in improved sludge settling, lesser sludge production, and a clearer effluent. The treatment efficiency increased and the four aeration tanks are now adequate for the process.


Textile Wastes

A textile firm has incurred large expenses in chemicals for their chemical waste treatment plant. As shown in Fig. 3. A treatability study was conducted to determine the feasibility of conver-' ting to biological treatment. Table 1 shows the result. Color reduction improved and the COD of. the raw wastewater was reduced from 486 mg/L to 32 mg/L after treatment. By shifting to biological process using the' NS series 'microorganisms, the company expects a savings of Pl.4 million a year.

Table 1  Results of the Treatability study of textile wastewater.

Parameters

Spl. # 1 Spl. # 2 Spl. # 3
pH 9.6 8.4 8.65
Color (Pt.-Co. Units) n.a. 44.5 21
Dissolved Oxygen, mg/L 0.0 8.0 9.8
Chemical O2 Demand, mg/L 486.0 9.7 32
Suspended Solids, mg/L 130.0 107.0 93
Dissolved Solids mg/L 1060.0 896.0 887
Total Solids mg/L 1192.0 1000.0 980

 

Sample #1 - Raw wastewater with distinct pink color

Sample #2 - Treated wastewater, aerated

Sample #3 - Treated wastewater, aerated and filtered

Fish Cannery Wastes

Food processing wastes contain high organic matter concentration. This indicates the suitability of biological forms of waste treatment. A particular fish-cannery'plant is using a chemical treatment system shown in Fig. 4. The system has some inadequacies (offensive odor and insufficient treatment), so that a treatability study was done on the raw wastewater as well as the water from the aeration ,tanks. Table II shows the results. The data show improvements in the influent wastewater characteristics 48 hours after inoculation of the microbial .strains. Using bioaugmentation without any pH adjustment and grease removal, we obtained 70% reduction in COD, 91% suspended solids removal and 56.5% total solids removal. The results on the aeration tank showed only a slight decrease in COD and total
solids content. The system shown in Fig. 5, a series of anaerobic and aerobic treatments in suitable for this type of waste. The NS series microorganisms are facultative, so they also work anaerobically.

Table II Result of the treatability Analysis on Cannery Waste

INFLUENT AERATION TANK

Parameter

Raw wastewater Untreated Treated Raw wastewater

Untreated

Treated

pH

5.75

7.60

7.60

7.60

8.30

8.50

COD. mg/L

3.673

2449

1098

680

314

295

Suspended Solids, mg/L

3279

321

269

539

387

50

Total Solids, mg/L

7504

3538

3267

2849

2818

2120

Raw wastewater - wastewater coming directly from the factory
Untreated - aerated wastewater
Treated - aerated wastewater with microbes added
The values for the treated and untreated samples are those taken after 48 hours of treatment


Figure 4.   An existing chemical treatment scheme for cannery wastes.



Figure 5.   A biological treatment scheme suitable for cannery wastes.



Agricultural Chemical Waaste

A herbicide manufacturer produces and effluent, high in phenolic wastes (see table III). Several consultants have submitted the proposals for the construction of a suitable plant but none was successful. According to the management. the waste treatment cost of a similar plant in the U.S. is twice the manufacturing of the product. Especially cultured microorganisms to metabolize the phenols should be used. A fluidized bed system shown in Fig. 6 is recommended for this type of wastewater.


Table III       The analysis of an agricultural chemical waste.

BOD

=

6,200 mg/L

COD

=

11,500 mg/L

Settleable solids

=

5 ml/L

Suspended solids

=

10,000 mg/L

Total solids

=

64,000 mg/L

Total dissolved solids

=

54,000 mg/L

Phenols

=

495 mg/L

Flow rate

=

17,000 L/day

 

 


Fig. 6.    A fluidized bed system for organic wastewaters. (Anon., 1979)

 


Distillery Wastes

Distillery slops is a dark brown-black liquid produced as a by-product in the alcoholic fermentation of molasses. This effluent has a BOD of 40,000 mg/L and 'a COD of 85,000. The untreated wastewaters of distillery plants cause severe stream pollution and affect the livelihood of many people. A treatability study on the waste of a certain distillery plant was performed. Table IV shows that aerobic treatment is inadequate.

The high organic content indicates that biogas production (anaerobic digestion) should be incorporated in the waste treatment process. The results on anaerobic digestion and digester design discussed in the next section are applicable to distillery slops.

Table IV

Sample

pH

Suspended

Solids (mg/L)

COD 

(mg/L)

BOD

 (mg/L)

Color (pt. co. units)

Raw wastewater

6.7

57

90,568

58,900

15,000,000

After 24hrs.

7.0

32

70,170

42,175

5,000,000

After 48 hrs.

7.3

26

43,465

27,280

4,000,000

 

 


Biogas Production

A preliminary experiment conducted by a graduate student in our department indicates that by incorporating the NS Series culture in the anaerobic digestion of pig manure, the methane production increases by 20%. Gas production is higher in the earlier stages which results in improved productivity. Figure 7 shows the shifting of the curve for the treated sample to the left, indicating more gas production at the early stages. NS Series bacterial culture is facultative and works well in the anaerobic digester. The enzymes produced by this bacteria degrades the high molecular weight substrates which results in a more efficient gas production.

 



New Biogas Digester Design for Swine Waste

Biogas production from swine waste can be more efficient by separating the solid fraction from the liquid fraction and anaerobically digested separately. The substrate becomes more accessible to the microorganisms resulting in a more efficient gas production. A new reactor design. for the solids fraction is shown in Fig. 8. The feed inlet is located at the center. Diagonal elliptical plates act as solid passage and as scum breaker. The feed inlet is at the bottom. Pyrolized coconut shell is packed in the support system for the microorganisms.


Fig. 8. A biogas digester design for the solid fraction of swine waste.



Support material

Fig. 10. The schematic diagram of a new microbial film biogas digester.

A New Biogas Digester for Liquid Wastes (Jose, 1988)

We have designed a new microbial film bioreactor for biogas production from liquid industrial and agricultural wastes. The reactor is able to operate continuously, has an inexpensive but efficient microbial support system, can handle a large capacity of wastes, and is easy to scale up. Fig. 10 shows a schematic diagram of the digester.

For optimum operation, a stage-wise system was incorporated. The box was divided into compartments such that the substrate passes through the support system in a plug-flow manner. In each compartment, a skeletal structure holds the support material made of plastic sheets, coconut shell (pyrolyzed or unpyrolyzed), or any other suitable waste material. (Jose and De Ungria, 1988) The digester shape is simple, and is a space saver if the structure is built below ground level. Tests are being conducted using distillery slops as the substrate.


 CONCLUSIONS 

With biotechnology, we can hope for a better environment. We can utilize the microorganisms, make them more efficient, and let them degrade the unwanted wastes and pollutants. The effort in the Philippines shows that using the new technology can mean savings for the waste treatment industry. More over, new and more efficient biogas digester design will add to the savings.


 ACKNOWLEDGMENT 

The author wishes to thank Mr. George Whang of Nu-Genes Technologies, Inc., for providing the bacterial cultures and Mr. Jose Ali Bedano for his work on the anaerobic digestion of swine wastes.

REFERENCES

American Public Health Association. 1981 Standard Methods for the Examination of Water and Wastewater. 15th Edition! Washington D.C.

Anon. 1979. Space Saving Wastewater Treatment. Chemical Engineering. McGraw-Hill Vol 86 No. 14 pp. 47-48.

Gasner, L.L. 1979. Microorganisms for Waste Treatment in Microbial Technology. Vol. II. H.J. Peppler and D. Perlman, eds. Academic Press. London.

Jose, W.I. and R. de Ungria. 1988. New Engineering Uses of Coconut Shell Charcoal. PICHE Journal. pp. 14-16.

Jose, W.I. 1988. Bioreactors Designed for Ease of Scale Up. Paper presented at the 10th Annual Meeting of the National Academy of Science and Technology (R.P.). Manila. 

Nemerow, N.L. 1971. Liquid Wastes of the Industry - Theories, Practices, and Treatment. Addison-Wesley Pub. Co., Reading.

Schonborn, W., ed. 1986. Microbial Degradations. Vol. 8 of Biotechnology H. - J. Rehm and G. Reed., eds. VCH. West Germany.

 

                      

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