This report summarizes a study that tested the utility of three bamboo species (Bambusa vulgaris, Dendrocalamus giganteus, and Bambusa X) for treating wastewater in Kenya. The bamboo were grown in pots irrigated with wastewater from a university treatment plant or clean water. Results showed that bamboo irrigated with wastewater had higher biomass, leaf area, chlorophyll content, and assimilation rates compared to those with clean water. While D. giganteus had the highest water use efficiency, B. vulgaris and B. X grew faster and had larger leaf areas, confirming the hypothesis that bamboo respond to wastewater by increasing nutrient uptake and leaf growth.

1. Utilization of Bamboo in Fixing Biomass From Wastewater Progress Report By Hunja Murage Supervisors: Prof. C. Ong, Dr.K. Ngamau, Dr. C. Muthuri

2. Introduction 1 ■ Water pollution is a major problem in Kenya. ■ Effluent from industries and human settlements is the main source of the problem. ■ Rural urban migration has given pollution an urban focus. ■ Effluent finds its way into the water supply: both surface and ground water.

3. Introduction 2 ■ The forest cover in Kenya is under siege, because of increased need for settlement, farmland and forest products. ■ Bamboo can, while providing a substitute for wood, because of its water pumping properties, be useful in fixing biomass from wastewater. ■ Wastewater from urban areas is not suited to growing food crops due to pollutants.

4. Objectives To test bamboo species for their utility in wastewater treatment. To test the tolerance of these bamboo species to high nutrient conditions.

5. Hypotheses ■ Different bamboo species respond to wastewater by taking up nutrients and increase leaf area. ■ Water use efficiency will remain relatively similar between species ■ Wastewater has little impact on water use efficiency

6. Materials & Methods ■ 3 bamboo species, Bambusa vulgaris, Dendrocalamus giganteus , and Bambusa X were used in this study. ■ They were grown in 100 litre pots at the JKUAT experimental farm, in a randomized complete block design. ■ Wastewater from the University treatment ponds was used to irrigate the plants

7. Materials & Methods ■ Growth parameters such as plant height, leaf number, number of branches, collar diameter were taken at monthly intervals. ■ Infra Red Gas Analyzer was used to measure assimilation, evaporation and stomatal conductance twice a week. ■ Measures of chlorophyll content were also taken using SPAD, and soil moisture levels monitored with a moisture metre.

8. Bamboo Wastewater Trial in Juja

9. Constitution of Juja wastewater ■ The levels of K and Na are very high. ■ This would have an effect in the opening and closing of stomata.

10. ■ The diurnal assimilation trend for the 3 bamboo species is the same. ■ The plants receiving wastewater (red) have higher levels of assimilation than clean water (black). (from 8am)

11. ■ The diurnal stomatal conductance trend for the 3 bamboo species is the same. ■ This supports the data on diurnal assimilation. (from 8am)

12. ■ D. giganteus has a higher Instantaneous WUE. ■ Plants receiving wastewater appear to have a higher WUE in comparison to clean water plants. giant

13. Stem & Branch Biomass ■ Plants receiving waste water (-w) had the biggest culm and branch weight. ■ Bambusa vulgaris (middle) did not show sensitivity to wastewater. B. vulgaris Giant B. x

14. Leaf Biomass ■ Total leaf weight showed a clear difference between plants receiving wastewater and clean water. Giant B. vulgaris B.x

15. Biomass ■ XW and VW had the highest number of new branches. ■ GW had a decrease in number of branches in the same period. B.x B.v. giant

16. ■ B. vulgaris and B.x had more than double the leaf area of the other treatments. ■ These treatments therefore have assimilation and evaporation rates that are three times of the other three.

17. ■ Wastewater plants (orange) had higher chlorophyll values

18. Preliminary Conclusions ■ Confirm hypothesis 1 that main responses to wastewater is increase in leaf area and chlorophyll. ■ Although giant bamboo appears to have a higher WUE it is also the slowest growing. ■ Water use efficiency was relatively similar although wastewater WUE appeared to be higher (significance?).

19. Further Studies ■ Different sources of wastewater particularly from industrial sites to be investigated. ■ A wider range of concentration of wastewater to be tested. ■ Analysis of nutrient uptake to be carried out.