INTRODUCTION:

Huge amounts of inorganic salt-containing wastewater are increasingly rising from several sources of domestic, industrial, urban effluent even in arid and semi-arid regions with soil salinization problems^1,2. Almost all of these salty wastewaters include not just inorganic salts, but also excessive nitrogen (N) and phosphorus (P) concentrations^3-5, accompanying salts, pesticides or herbicides, humus², household wastewater, acid rain, heavy metals, and several other inorganics and organic chemical substances³. Nutrient enrichment in water bodies can contribute to an increase in algae growth and a decrease in dissolved oxygen, which may further disrupt the equilibrium of the ecological structure^6,7.

Apart from nutrients, high concentration inorganic salt ions may affect the intracellular and extracellular osmotic pressure balance of microorganisms, minimize enzymatic activity, and even induce microbial depletion and death^8,9. Over the last few decades, numerous engineering-based remediation methods have been developed for the purifying of saline wastewater and sites. It is a daunting job to find an effective remedial approach. The most common technologies are (a) immobilization technologies (b) toxicity reduction technologies, and (c) Separation/concentration technology. The high price of these inventions was one of the hurdles that prevented their wide acceptance¹. Phytotechnologies, integrating physical, chemical, and biological processes, have major benefits, such as stable running performance, lower operating costs, easy handling, eco-friendly properties, and esthetic values^9-11. Phytotechnologies are shown to surpass traditional biological techniques for the removal of nutrients^2,13. Moreover, certain halophytic plants can use excessive salts which may reduce the toxicity of salt to other accessible creatures within the system¹⁴. For this cause, the choice of two halophytic plants Tamarix Boveana and Salsola Baryosma accorded to their survival naturally, thrive, and complete their life cycle¹³ under salinity stress (electrical conductivity (EC) > 4 mS/cm) according to authors⁹. The objective of the current study is to use plants which existing naturally in a Halloufa wetland (site not studied before), to reduce the nitrogen and phosphorus in the case of saline stress under the same conditions (climatic conditions, effluent, etc).

MATERIALS AND METHODS:

Presentation of area study:

Halloufa wetland (HW) considered to be a wastewater discharge located 45 km northwest of the El-Oued region (south-east of Algeria) (Fig.1) Geographically, (HW) is restricted by the following coordinates: n X = 06 ° 51' East and Y1 = 33 ° 42' and Y2 = 33 ° 47' North. The region characterized by an arid climate, the hot season lasts from May to October, with an average temperature of 29.98 ° C. The cold cycle is from November to April, with an average of 14.99°C. The rainy season of the year is fairly limited (2 to 3 months), the average annual rainfall is around 5.47 mm.

Experimental design and operation:

The experiment was carried out at the wastewater purification station of Kouinine (north of the city of El-Oued), Algeria. The two emergent wetland plant species; T. boveana and S. baryosma, were collected from (HW), in October 2019. These species have been shown to grow well in an arid climate and under salinity conditions (reach until EC at 50 mS/cm stress in summer). In the Experiment, two buckets made of non-transparent Polyethylene (25 cm in diameter and 37 cm in height) (Fig.2) were filled at the heights of 7 cm, 7 cm, and 15 cm from the bottom (thick, fine gravel and sol with an equivalent diameter of (15/25) mm, (4/12.5) mm and (clay (10%)- sand (90%)) respectively. A drainage tap was installed on each bucket at the height of 2 cm from the bottom. The plants transplanted into each bucket, planted bucket (PB) with rhizomes measuring approximately 8 dm³ at a density of (35 stems/m²) is 2 yong stems for each¹⁵. And the third bucket remained unplanted as a reference point (RB). All buckets are supplied with (3 to 4) L of primary wastewater treatment per vertical surface flow system at regular intervals weekly.

Fig.1. Geographic map of Halloufa wetland

Fig.2. Schematic diagram of the experimental setup

Samples analysis:

The flow was induced by percolation through the substrate. The water is residence time is 5 days. Treated water is collected by the tap at the bottom of the bucket. The analyzes were carried out in the Algerian water laboratory and the Kouinine wastewater treatment plant laboratory. Our measurements related to four parameters (NH⁺₄-N), (NO^-₂-N), (NO^-₃-N), and orthophosphates (PO₄^3--P) were carried out using Spectrophotometry (Hach Odyssey) methods. The conductivity was determined by using (multi-parameter Terminal 740). Monitoring continued throughout the period from November 2019 to March 2020.

RESULTS AND DISCUSSION:

In this study, the nutrient removal under salt stress ranged between (EC 10-15 mS/cm), the average pH values are (7-8), and DO are (8-9 mg/l) was observed in (PB)s and (RB).

Evolution of the Ammonia:

The evolution of the NH₄⁺ -N wastewater concentration at the entrance and exit of both (PB)s and (RB) during the treatment period are shown in (Fig.3). Effluent NH₄⁺ -N concentrations decreased in all buckets, and the removal percentages of NH₄⁺-N were ~100% for both (PB)s, while 95% removal for the (RB).

This observation can be explained by authers¹⁶ which reported that the nitrification process that transforms NH₄⁺ -N to NO₃^- -N. The NH₄⁺-N is oxidized into NO₂^- -N by ammonia-oxidizing bacteria (AOB), while NO₂^- -N is oxidized to NO₃^- -N by nitrite-oxidizing bacteria (NOB), in the presence of oxygen, while nitrifying bacteria as autotrophic groups (AOB, NOB) are less sensitive to salt stress. According to the authors¹⁷, not all NH₄⁺ -N within bacterial cells are nitrified, while NH₄⁺ -N is the energy source for nitrifiers. Section of NH₄⁺ -N is used for cell growth as a source of nitrogen where carbon dioxide is used as a source of carbon. ‘

Fig. 3. Evolution of the Ammonia of wastewater to the entrance and exit of the systems planted and unplanted

Evolution of the Nitrites:

Evolution of the NO₂^-- N wastewater concentration at the entrance and exit of both (PB)s and (RB) during the treatment period, are shown in (Fig.4). For the (RB) the reduction oscillates between 2% (January) and 30% (December), the maximal reduction noted in (PB) with T. boveana of 90% (March) and decreases to 48% during (November). For (PB) by S.baryosma, the high reduction of 80 % was obtained in (December), then decreases to 5.6% during (January). However, an accumulation of NO₂^- -N concentration from 0.62 mg/l to (0.87–1.09 mg/L) was observed in (February) for T. boveana and S. baryosma buckets respectively.

According to previous studies, this accumulation explains the presence of inhibitory factors (salinity). Wang et al. indicate that the salinity at (EC 15 mS/cm) led to a negative impact on microorganisms richness in buckets¹⁸. Although, ammonia-oxidizing bacteria (AOB) are less affected by salinity. that means, only short-cut nitrification can be performed in buckets under salt tension, resulting in a large accumulation of NO₂^- -N.

Fig.4: Evolution of the Nitrites of wastewater to the entrance and exit of the systems planted and unplanted

Evolution of the Nitrates:

Evolution of the NO₃^- -N wastewater concentration at the entrance and exit of both (PB)s and (RB) during the treatment period, are shown in (Fig.5). Throughout the experiment, the nitrate increases in all buckets (Fig.5) except in (December), when reaching at reduction percentage of (64.33%, 62.23%, 15.38%) in S. baryosma, T. boveana, and control bucket respectively. while appearing a negative removal in the rest months.

The increase in NO₃^- -N concentration represents the NO₃^- -N accumulation, which interpreted by authers¹⁸ the behavior of the rhizosphere microbes was influenced by an increase in salinity levels in the medium resulting in a decrease in denitrification ability. Also, according to authers¹⁹, this is possibly due to the filamentous algae formed in the environment when the wastewater was exposed to sunlight during the experiment. With ample direct sunlight, the algae will generate oxygen by photosynthesis, and the oxygen in the water column will dissolve. This dissolved or usable oxygen helped the nitrification process, which has a high oxygen demand and thus raises the oxygen demand. The presence of highly oxygenated water also suppressed the denitrification process.

Fig. 5. Evolution of the Nitrates of wastewater to the entrance and exit of the systems planted and unplanted

Evolution of the Orthophosphates:

Evolution of the PO₄^3--P wastewater concentration at the entrance and exit of both (PB)s and (RB) during the treatment period, are shown in (Fig.6). an increase showing in (November) at all buckets, that can be explained by the presence of phosphate in the substrate drained into the outlet. But a reduction observed from (December) to (March). For (RB), the reduction varies between 19.67 % (December) and 52.38 % (February). The maximal reduction noted in (PB) with S. baryosma of 94.50 % (February) and decreases to 28.41 % during (December). For (PB) by T. boveana, the high reduction of 88.64 % was obtained in (February), then decreases to 45.9 % during (December).

The involvement of plants is the explanation for the significant decrement compared to (RB) in the phosphate concentration in our phytoremediation system. Phosphorus is a plant macronutrient^20,21 and a major component of ADP and ATP that is essential for energy storage and transport in photosynthesis and respiration. It is required in the formation of ADP and ATP, as well as in the construction of their biochemical structural components such as nucleic acids, nucleotides, sugar phosphates, etc. especially during their growth¹⁸.

Fig. 6: Evolution of the Orthophosphates of wastewater to the entrance and exit of the systems planted and unplanted

CONCLUSIONS:

The results obtained during the whole study revealed that the plants T. Boveana and S. Baryosma provide adequate treatment for most of the nutrients in the sense of salt stress and arid climate. There is an increase in the purification production from (RB) compared to the planted buckets. Satisfactory outputs for nitrogen (ammonia and nitrite) and phosphorus contamination have been obtained for the two plant species tested, removal efficiencies reached 98% for the ammonia, 67% for the orthophosphates, 64% for the nitrate, and 45% for the nitrite. The (PB) of T. boveana provides the best outputs for the removal of nitrogen pollution, as opposed to phosphate pollution, the (PB) of S. baryosma which is most fitting. An accumulation was observed in nitrate at most treatment period.

CONFLICT OF INTEREST:

The authors declare no conflict of interest

REFERENCES:

1. Nouri H, Chavoshi S, Nirola R, Hassanli A, Beecham S, Alaghmand S, Saint C, Mulcahy D. Application of green remediation on soil salinity treatment : A review on halophytoremediation. Safety and Environmental Protection. 107; 2017: 94–107.

2. Yan B, Shutes B, Cheng X, and Chen X. Removal of nutrients in saline wastewater using constructed wetlands: Plant species, influent loads and salinity levels as influencing factors. Chemosphere. 187; 2017: 52-61.

3. Ali A, Naeem M, Singh S, and Alzuaibr F M. Phytoremediation of contaminated waters: An eco-friendly technology based on aquatic macrophytes application. The Egyptian Journal of Aquatic Research.

4. Wang S, Gao M., Wang Z., She Z., Jin C., Zhao Y., Guo L., Chang Q. Effect of oxytetracycline on performance and microbial community of an anoxic–aerobic sequencing batch reactor treating mariculture wastewater. RSC Advances. 5(66); 2015: 53893–53904.

5. Schindler D W, Carpenter S R, Chapra S C, Hecky R E, and Orihel D M. Reducing phosphorus to curb lake eutrophication is a success. Environmental Science and Technology. 50 (17); 2016: 8923–8929.

6. Hayes M A, Jesse A, Tabet B, Reef R, Keuskamp J A, and Lovelock C E. The contrasting effects of nutrient enrichment on growth, biomass allocation and decomposition of plant tissue in coastal wetlands. Plant and Soil. 416 (1–2); 2017: 193–204.

7. Wirnkor V, Ngozi V, and Emeka A. Water Pollution scenario at river Uramurukwa flowing through owerri metropolis, IMO State, Nigeria. International Journal of Environment and Pollution Research. 6; 2018: 38-49.

8. Wang J, Zhou J, Wang Y, Wen Y, He L, and He Q. Efficient nitrogen removal in a modified sequencing batch biofilm reactor treating hypersaline mustard tuber wastewater: The potential multiple pathways and key microorganisms. Water Research. 177; 2020: 115734.

9. Panhwar Q A, Naher U A, Depar N, and Ali A. Salt Stress, Microbes, and Plant Interactions: Mechanisms and Molecular Approaches. Springer Nature Singapore Pte Ltd. Singapore, 2019.

10. Sugar S, Rastogi A. Adsorptive Elimination of an Acidic Dye from Synthetic Wastewater using Yellow Green Algae along with Equilibrium Data Modelling. Asian Journal of Research in Chemistry. 11 (5); 2018: 778–786.

11. Wang Y, Sun B, Gao X, and Li N. Development and evaluation of a process-based model to assess nutrient removal in floating treatment wetlands. Science of the Total Environment. 694; 2019: 133633.

12. Rai P K. Phytoremediation of Emerging Contaminants in Wetlands. CRC Press, India. 2018.

13. Mirza H, Sergey S. Masayuki F. Halophytes and climate change: adaptive mechanisms and potential uses. CABI, UK. 2019.

14. Wang Z C, Gao M C, Ren Y, Wang Z, She Z L, Jin C J, Chang Q B, Sun C Q, Zhang J, Yang N. Effect of hydraulic retention time on performance of an anoxic–aerobic sequencing batch reactor treating saline wastewater. International Journal of Environmental Science and Technology. 12 (6); 2015: 2043–2054.

15. Bebba A A, Labed I, Zeghdi S, and Messaitfa A. Purification Performance of Typha Latifolia, Juncus Effusus and Papyrus Cyperus in Arid Climate: Influence of Seasonal Variation. Journal of Water Chemistry and Technology. 41 (6); 2019: 396–401.

16. Wongkiew S, Hu Z, Chandran K, Lee J W, and Khanal S K. Nitrogen transformations in aquaponic systems: A review. Aquacultural Engineering. (76); 2017: 9–19.

17. Ge S, Wang S, Yang X, Qiu S, Li B, and Peng Y. Chemosphere Detection of nitrifiers and evaluation of partial nitrification for wastewater treatment: A review. Chemosphere. 140; 2015: 85-98.

18. X. Wang, Zhu H, Yan B, Shutes B, Bañuelos G, and Wen H. Bioaugmented constructed wetlands for denitrification of saline wastewater: A boost for both microorganisms and plants. Environment International. 138; 2020: 105628.

19. Ng Y S and Chan D J C. Wastewater phytoremediation by Salvinia molesta. Journal of Water Process Engineering. 15; 2017: 107–115.

20. Rajta A, Bhatia R, Setia H, and Pathania P. Role of heterotrophic aerobic denitrifying bacteria in nitrate removal from wastewater. Journal of Applied Microbiology. 128, 1261–1278.

21. Bhateria R and Jain D. Water quality assessment of lake water: a review. Sustainable Water Resources Management. 2 (2); 2016: 161–173.

Received on 11.10.2020 Modified on 05.12.2020

Asian Journal of Research in Chemistry. 2021; 14(3):203-207.

DOI: 10.52711/0974-4150.2021.00036