Effect of Phase Change Materials on Water Yield in a Weir-Type Cascade Solar Desalination Still

Ron Eric B. Legaspi^1,2, Alfred T. David³, Mary Joy B. Bio³, Angela Adien Rose F. Marquez³, Angelica A. Zoilo³, Mark Joseph B. Enojas³

¹ College of Professional and Graduate Studies, De La Salle University – Dasmariñas, Cavite, Philippines
² Basic Arts and Sciences Department, Technological University of the Philippines – Taguig, Metro Manila, Philippines
³ Bachelor of Engineering Department, Technological University of the Philippines – Taguig, Metro Manila, Philippines

ABSTRACT

To address potable water scarcity in the Philippines, this study investigated an enhanced desalination method using a weir-type cascade solar still integrated with three phase change materials (PCMs): paraffin with powdered graphite (PPG), erythritol (ETL), and soybean wax (SBW). The prototype utilized convex lenses and copper tubes to optimize thermal energy storage, enabling sustained evaporation even after sunset. Performance was evaluated based on daily water yield, cost-effectiveness, and potability over five-day trials for each PCM.  Statistical analysis confirmed that environmental conditions remained consistent across trials, with no significant difference in solar irradiance (p = 0.9819). Results demonstrated that PPG achieved the highest average water yield at 2.22 L/day, significantly outperforming ETL (1.67 L/day) and SBW (1.42 L/day) (p < 0.001). Conversely, SBW was the most cost-effective option, yielding an amortized cost of 1.46 pesos/L, compared to 1.92 pesos/L for ETL and 2.40 pesos/L for PPG (p < 0.001). Furthermore, comprehensive physicochemical and microbiological testing confirmed that the produced distillate met the Philippine National Standards for Drinking Water. The study concluded that PCM-integrated solar desalination is a viable solution for producing safe drinking water. It highlighted a strategic trade-off: PPG is ideal for maximizing yield due to its superior thermal conductivity, while SBW is the most economically feasible in resource-constrained areas. These findings emphasize that PCM selection and structural optimization are critical for enhancing solar distillation productivity.

Keywords: Desaltation, Distillation, Erythritol, Paraffin, PCM, Soybean Wax, Thermal Storage, Water Scarcity

Cite this Article:

Legaspi REB, David AT, Bio MJB, Marques AARF, Zoilo AA, & Enojas MJB. 2025. Effect of Phase Change Materials on Water Yield in a Weir-Type Cascade Solar Desalination Still. Lasaliksik. 3(1).

Some Generator Subgraphs of the Flower Graph

Ma. Theresa Christine C. Valdez

Mathematics and Statistics Department, De La Salle University, Dasmariñas

ABSTRACT

This study investigated the edge space of the flower graph G = Fl_n with order and size 2n + 1 and 4n, respectively. Its edge space, denoted by E (Fl_n), consists of all the subsets of its edge set E(Fl_n), thus |E (Fl_n)| = 2⁴ⁿ and dim (E (Fl_n)) = 4n. The study also determined some of the generator subgraphs of the flower graph, Fl₃. Suppose H is a subgraph of a graph G, then the uniform set of H with respect to G is the set E_H(G) = {A| AÎ E (G), G[A] @ H} consisting of elements of the edge space such that G[A], the subgraph of G induced by the edges in A, is isomorphic to H. We say H is a generator subgraph of G if every element in E (G) can be expressed as a linear combination of elements in E_H(G). It was found that subgraphs H of the flower graph such as paths P₄ and P₃ È P₂; tadpole graphs T_3,2 and T_4,1; and kite graph Kt_1,1 are generator subgraphs of G = Fl₃ by expressing the singleton elements {e_i} Î E (Fl₃), 1 £ i £ 4n as a linear combination of elements found in E_H(Fl₃). Further, the study demonstrated the use of an isomorphism based on the rotational symmetry of a flower graph in finding a linear combination for the singleton elements of its edge-space.

Keywords: edge-set, edge space, flower graph, generator subgraph, uniform subgraph

Cite this Article:

Valdez MTCC. 2025. Some Generator Subgraphs of the Flower Graph. Lasaliksik. 3(1).

Assessment of Total Coliform Contamination and Sanitation Sources in the Galo River, Batangas, Philippines

Riann Yee Dragon¹, Johnny A. Ching^1,2, Airill L. Mercurio^1,2

¹College of Professional and Graduate Studies, ²College of Science

De La Salle University-Dasmariñas, City of Dasmariñas, Cavite

ABSTRACT

Total coliform (TC) concentration is a widely used microbial indicator of fecal contamination and deteriorating water quality in freshwater ecosystems. This study assessed TC contamination in the Galo River, Nasugbu, Batangas, Philippines, and identified potential sanitation-related sources contributing to microbial pollution. Water samples collected from upstream, midstream, and downstream stations during dry and wet months were analyzed using the Most Probable Number (MPN) method through a third-party accredited laboratory. Key informant interviews and household surveys were also conducted to determine sanitation practices and possible contamination pathways within adjacent communities. Results revealed critically elevated TC levels across all sampling stations, ranging from 10.8 to 180 times above the DENR DAO 2016-08 standard of <3,000 MPN/100 mL. Mean TC concentration during dry months (2.75 × 10^5 MPN/100 mL) was substantially higher than during wet months (1.51 × 10^4 MPN/100 mL), indicating reduced dilution and greater accumulation of fecal contaminants during low-flow conditions. Upstream stations recorded the highest contamination levels, suggesting localized point-source inputs. Household sanitation assessment revealed that 42.8% of respondents lacked septic tanks while 28.6% were engaged in backyard piggery or poultry operations, many of which discharged untreated wastes directly into nearby soils or waterways. These findings demonstrate that inadequate domestic sanitation and unmanaged livestock wastes are major contributors to microbial contamination in the Galo River. Strengthened sanitation infrastructure, improved waste management practices, and stricter regulation of small-scale livestock operations are urgently needed to reduce fecal pollution and support sustainable watershed management in rural river systems.

Keywords: total coliform, microbial contamination, sanitation, piggery waste, freshwater pollution

Cite this Article:

Dragon RY, Ching JA, & Mercurio AL. 2025. Assessment of Total Coliform Contamination and Sanitation Sources in the Galo River, Batangas, Philippines. Lasaliksik. 3(1).

Community Perception of Mangrove Forests in Barangay Navotas, Balayan, Batangas, Philippines

Wirmie N. Dedase^{1 2*}, Mario A. Cudiamat^1,3

¹College of Professional and Graduate Studies, De La Salle University- Dasmariñas

Dasmariñas City Cavite, 4115 Philippines

²Dasmariñas North National High School San Isidro Labrador 1, Dasmariñas City, Cavite Philippines

³Institute of Biological Science, College of Arts and Sciences, University of the Philippines Los Baños, Laguna, Philippines

ABSTRACT

Mangrove forests provide critical ecological, protective, and socioeconomic services to coastal communities, yet they remain highly vulnerable to anthropogenic degradation and land-use conversion. This study assessed community perceptions of mangrove ecosystems in Barangay Navotas, Balayan, Batangas, Philippines, focusing on their socioeconomic and ecological values, attitudes toward conservation, and practices related to mangrove use and care. A descriptive cross-sectional design was employed using validated survey questionnaires and focus group discussions. A total of 100 coastal household respondents were selected through purposive sampling. Descriptive statistics, including frequency, percentage, mean, and standard deviation, were utilized for data analysis. Results revealed high perception of the ecological and socioeconomic importance of mangroves (grand mean = 3.09), particularly in relation to fisheries productivity, coastal protection, and shoreline stabilization. Positive conservation attitudes were also observed (grand mean = 3.15), including support for mangrove protection laws, clean-up initiatives, and rehabilitation activities. Practices related to mangrove conservation likewise garnered generally favorable responses (grand mean = 2.55), especially in waste segregation and participation in environmental programs, while extractive utilization of mangroves remained low. The findings indicate that the community possesses substantial awareness and favorable attitudes that may support community-based mangrove management initiatives. Strengthening environmental education, participatory governance, and localized conservation programs is recommended to enhance long-term sustainability and coastal resilience.

Keywords: mangrove conservation, community perception, coastal management, ecological values, community-based management, Philippines

Cite this Article:

Dedase WN & Cudiamat MA. 2025. Community Perception of Mangrove Forests in Barangay Navotas, Balayan, Batangas, Philippines. Lasaliksik. 3(1).

LASALIKSIK

Editorial Board

Editor-in-Chief

                             Dr. Johnny A. Ching (Biology, De La Salle University-Dasmariñas)

Associate Editor   

                             Dr. Nelda A. Nacion (Mathematics, De La Salle University- Dasmariñas)

Managing Editor

                             Jaime Zeus Agustin (De La Salle University- Dasmariñas)

Members